# LED Light for 36" High Tank



## Rockhoe14er (Jan 19, 2011)

wow. lucky member. I can't wait to see this build.


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## Hoppy (Dec 24, 2005)

The goals were:
Get 40-50 mms of PAR, for sure, with good probability of being able to get twice that.
Moonlights.
Hanging no more than 20 inches above the top of the tank.
Good coverage of the whole tank.
Some shimmer effect, if possible.
No fans, if possible.

I believe I can meet all of those requirements, and have the ability to do some limited adjustment of the color temperature too.

The parts cost? So far it is:









I have my fingers crossed as to whether I will make a profit on this.


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## O2surplus (Jan 31, 2010)

It looks good to me- Hoppy. I think that you'll get close to twice the PAR you're aiming for.


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## Hoppy (Dec 24, 2005)

It's amazing what you can do, at least in theory, with optics on LEDs. I plan to calibrate the light so it is possible to dial in the PAR you want - any combination of the two colors of LEDs. The only problem I see with that is that so much of the light will be reflected off the glass, that my in-air calibration could be 20% or so low. That is still pretty good - aim for 50 mms of PAR and get 60 in water.

As I see it, the biggest problem with lighting a 36 inch high tank is the huge range of PAR values from substrate height to the top of the water. Raising the fixture a foot helps with that, but raising it 3 feet would have helped a lot more. I'm thinking that the next iteration on obtaining the "best" light will be when we can get a light that keeps the PAR within +/- 20% from top of tank to bottom of tank.


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## O2surplus (Jan 31, 2010)

Hoppy, you've got a solid design-I wouldn't lose any sleep over the PAR level variations. Plants seem to be pretty adaptable to varying amounts of light from what I've seen in my own tank. I've got JAVA FERN that is thriving, and is growing directly under my led rig. The ferns are only 10" down from the lights, and a complete carpet of Glossostigma is spreading like crazy at the substrate 34" down. According to every aquatic plant book that I've ever read, this should not be possible. I guess- no one ever told my ferns about their low light requirements, HeHeHe.


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## audioaficionado (Apr 19, 2011)

As his plants grow taller, some of that glass reflections to the substrate will be absorbed. Too much light is better than not enough as you can dim it at first and raise it as the plants grow in. Very nice plan for the rest of us DIY LED guys to model from.


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## sns26 (Mar 29, 2010)

If your calculations are right, then my own array (27 mostly XP-Gs over a 36"x18"x20"h tank) is going to be a fryalator, not a light source. But I knew from the start that I might be going overboard.

What are you going to use to drive the moonlights?


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## IWANNAGOFAST (Jan 14, 2008)

sns26 said:


> If your calculations are right, then my own array (27 mostly XP-Gs over a 36"x18"x20"h tank) is going to be a fryalator, not a light source. But I knew from the start that I might be going overboard.
> 
> What are you going to use to drive the moonlights?


I have 24 XP-g over the same size tank, even at 30" from substrate it's high light.


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## Hoppy (Dec 24, 2005)

sns26 said:


> If your calculations are right, then my own array (27 mostly XP-Gs over a 36"x18"x20"h tank) is going to be a fryalator, not a light source. But I knew from the start that I might be going overboard.
> 
> What are you going to use to drive the moonlights?


I'm hoping that with 1300 mAmps the light will be high light, so when dimmed, and the color adjusted, it will be 40-50 mms of PAR. The 3 moonlight LEDs will have their own 350 mAmp driver, not adjustable, but also not very bright at that distance, with 60 degree optics. I think I would leave the moonlights running along with the other LEDs, to add some blue for better color in the fish.

I have the heatsink and aluminum channels screwed together now. I used a flat sanding block to flatten the mating surfaces, and used some heatsink grease between them for better heat transfer. Now, I'm struggling with installing the hanging kit, from RapidLed - as they noted, it doesn't fit well between fins on the heatsink I have. It only lacks about 1/32 inch of making it, so a small rotary file should make room.


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## bryfox86 (Apr 6, 2011)

Subscribed! thinking about doing either LED or a DIY MH/CFL (ADA Style) for my 150 cant wait.


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## Hoppy (Dec 24, 2005)

bryfox86 said:


> Subscribed! thinking about doing either LED or a DIY MH/CFL (ADA Style) for my 150 cant wait.


A pure LED light is much better than any alternative, if you can swing the cost. And, DIY LED lights can be whatever you want them to be - the available LEDs today can do just about anything you would want on a planted tank. DIY reduces the cost down to be competitive with most non-LED lights.


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## Hoppy (Dec 24, 2005)

I finally got the hanging kit installed, using aluminum spacers to make it fit.










From the LED side, you can see the screws holding the channel extrusions to the heatsink, and the connector that will bring in the power to the LEDs. Later today I expect to add the wires to the connector, in preparation for getting the LEDs - some day?


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## Rockhoe14er (Jan 19, 2011)

Where did you find those aluminum pieces that you attached to the heat sink? also did you have to cut the aluminum?


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## audioaficionado (Apr 19, 2011)

Looks like Hoopy just bonded two C channels onto the main heat sink.


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## Rockhoe14er (Jan 19, 2011)

haha i wish i new more about metal working and where to find some of these metal pieces....lol. Did you get the C channels from a scrap yard?


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## audioaficionado (Apr 19, 2011)

If you can't find the metal stock locally, there's always McMaster-Carr


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## Rockhoe14er (Jan 19, 2011)

I can find big company's the sell huge quantities of aluminum. But not like a store like home depot or ace hardware that sell a much smaller quantity.


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## audioaficionado (Apr 19, 2011)

You can order single pieces from McMaster-Carr. You don't need to order a pallet's worth. I only mentioned them if you couldn't source it locally.


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## Hoppy (Dec 24, 2005)

The aluminum pieces, are 2" x 1" x .06" 6061T6 aluminum channel. There is a store near me that sells surplus metals, from aluminum to brass to steel to stainless steel, etc. in many forms. They have a good supply of aluminum extrusions, and even some heatsink aluminum. It is called "Blue Collar Supply". http://www.onlinemetals.com/merchant.cfm?id=64&step=2 is where I would get it if the store wasn't here. I bought an 8 foot section of the channel and cut two 32 inch long pieces from it for this project. It is very thin walled channel, not good for a heatsink, but I want it to act as a shield to protect people's eyes, and to prevent bumping the LEDs. It does add some heatsink mass, but not much.

Those two pieces are attached to the heatsink by drilling and tapping 6-32 threads in the heatsink, and using 3/8" long pan head screws.

I got the electric connector from a local electronics hobbyist supply store. It is a 4 conductor DIN connector, with the female socket on the light, and the male plug on the 4 conductor cable, to connect it to the power/control box. It would be better to have the male connector on the light and the female on the cable, but I didn't see a way to do that easily. The wire in the cable is 22 gauge, a bit small, but still adequate for the 10 foot length. And, it is nice and flexible. One conductor will carry the positive voltage for each of the 3 rows of LEDs, and the fourth will be the common negative conductor for all of the LEDs.


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## Rockhoe14er (Jan 19, 2011)

any reason to not use self tapping screws? to attach the c channel?


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## Hoppy (Dec 24, 2005)

Rockhoe14er said:


> any reason to not use self tapping screws? to attach the c channel?


Yes, it is difficult to tap 6061T6 aluminum. The metal shavings tend to become a gummy mess on the tap. This way I don't have to worry about that. I just back off the tap, clean it, and continue, a couple of times. I think self tapping screws would tend to seize up. In any case I had the tap, and I knew it would work, so why risk something different?

I got the wiring from the light connector to the LEDs installed today.









I used silicone sealant to fill the holes in the channels where the wires go through, to keep them from rubbing on the wire insulation. And, I used a few dabs of the same sealant down the middle between the channels, which is a wire chase, to keep the long wires from drooping down.

Tomorrow I will wire up the matching DIN plug, ignoring which wire goes where. Then, I can connect it to the light and use an ohmmeter to identify which color goes to which LED, and label them with tape, for the next step, which will be assembling the power/controls box.


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## Hoppy (Dec 24, 2005)

Soldering the wires to the male connector was more difficult than I expected, but, with patience, it was doable. Next is the power/control box.


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## Rockhoe14er (Jan 19, 2011)

Hoppy said:


> Yes, it is difficult to tap 6061T6 aluminum. The metal shavings tend to become a gummy mess on the tap. This way I don't have to worry about that. I just back off the tap, clean it, and continue, a couple of times. I think self tapping screws would tend to seize up. In any case I had the tap, and I knew it would work, so why risk something different?



on smaller pieces of aluminum can you use self tapping screws? like if you're trying to attach a 1/2 inch strip to a heat sink?


Also great job this fixture looks amazing.


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## audioaficionado (Apr 19, 2011)

If you predrilled the heat sink to just slightly less than the outside screw thread diameter, it should work. If it starts to get hard to turn the screw in, back off and try again. If not then the hole needs to be reamed slightly more with the same drill bit.


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## Hoppy (Dec 24, 2005)

Most of the big stuff is mounted in/on the project box now. The Meanwell drivers on each side and the tiny moonlight driver on the end. The 10 volt DC reference adapter is mounted inside the box, since the power it will consume should be trivial. It looks very crowded now, but most of that is excess wiring. The Ammeters, pots for dimming, and a switch to turn off the ammeters, will all be on the box cover. I still haven't received the ammeters, but those should arrive any day now, based on my experience with another order to the same guy in China. And, as expected, the LEDs and optics aren't here yet. I can still do a lot of wiring before needing the ammeters to finish that job. It has been fun so far - except having to run off to Home Depot (near) and Metro Electronics (farther) so often.


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## redfishsc (Aug 29, 2010)

Very nice write up Hoppy, I'm reading it eagerly. 

Are the blues for moonlights? I'd recommend not using optics then, or at least make them easy to remove. 


If they are there to raise the K temp, the 60's will work fine . 


And this is the first build using XML optics I've seen. You may have said this already but where are you getting these hard-to-find optics? LEDgroupbuy?


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## Hoppy (Dec 24, 2005)

redfishsc said:


> Very nice write up Hoppy, I'm reading it eagerly.
> 
> Are the blues for moonlights? I'd recommend not using optics then, or at least make them easy to remove.
> 
> ...


The blues are for moonlights, and will probably run with the other LEDs to give a bit more color for neons, cardinals, etc. I will use 60 degree optics on them to avoid spillage, given the 1 foot height of the light over the tank. All of the LEDs and optics are from LEDgroupbuy - or will be if I ever get them. (I'm a very impatient person when I start a project)

Very few of the ideas in this light are mine - I copied from other light builds I have read about here. I think this is how we can eventually find the "best" ways to do LED lights - keep building on each other's ideas.


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## Hoppy (Dec 24, 2005)

I have about all that I can do done, until the ammeters or LEDs arrive. I cut the holes for the ammeters using a utility knife, first putting masking tape on the surface, then marking the needed cutout outline. Since the box is polypropylene it cuts pretty easily with a utility knife. About the hardest part so far was installing the strain relief bushings. The first one took me close to an hour, with drilling the hole and reaming it ever larger until the bushing would go in. But, those sure make a neat installation.


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## Hoppy (Dec 24, 2005)

Progress report:
Yesterday I wired up the dimmer circuits - 2 10K ohm pots and a 10 volt wall wart type power supply. When I tested it one pot raised the voltage going clockwise and the other raised it going counterclockwise. I quit for the day in frustration.

Today I took another look, and found that I had made two mistakes. One was to confuse the rotation directions because I'm working on the back of the pots, and the other was that both pots raised the voltage in the counterclockwise direction. So, I moved one wire and now both operate correctly - raise the voltage with clockwise movement of the knobs.

Then I noticed another mistake: the switch to turn off the ammeters was wired to turn off the dimmers. That fix was just moving one wire, too.

All that is left on the power/controls box is to install and hook up the ammeters, once I receive them. I double checked on how long it took to get the first one I ordered two months ago - it is still early, based on that. They should arrive this week.

The LEDs and lenses are still shown on the ledgroupbuy site as not yet fulfilled, so it may be some time before I see those. They don't provide estimated times there.


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## redfishsc (Aug 29, 2010)

Hoppy said:


> Progress report:
> Yesterday I wired up the dimmer circuits - 2 10K ohm pots and a 10 volt wall wart type power supply. When I tested it one pot raised the voltage going clockwise and the other raised it going counterclockwise. I quit for the day in frustration.


My two dimmers do this, but I just left it. I keep them hidden from view and I'm the only one that uses them lol. I just need to reverse the outer pins to fix it.



> The LEDs and lenses are still shown on the ledgroupbuy site as not yet fulfilled, so it may be some time before I see those. They don't provide estimated times there.


They send out emails on the ETA. If you're not on that email list (if someone else ordered them and shipped them to you), send Milad an email and ask him to add you since you're the one waiting for them and doing the legwork. He's good to work with.


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## Hoppy (Dec 24, 2005)

The ammeters arrived today, so I should get the power/control module finished tomorrow. I'll wait another week before bugging ledgroupbuy about that order.


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## sns26 (Mar 29, 2010)

This is going very nicely. I'm watching carefully to see how your control box goes together. Right now my dimmer/driver rat's nest is screwed to a board and slid under the stand. I guess I follow redfish's "I'm the only one who messes with that anyway" approach.


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## Hoppy (Dec 24, 2005)

All the connections made! The ammeters come on when the switch is flipped to the on position, so that much works. The rest will await when I get the LEDs and get them installed.

The finished box looks about like I envisioned. I don't think I could have made it any smaller.


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## Rockhoe14er (Jan 19, 2011)

wow that looks so professional. How difficult is it to wire the knobs to the ammeters? Does this require calibration or is it when the know is all the way to the right it's at 100% and when it's all the way to the left it's 0%?


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## Hoppy (Dec 24, 2005)

Rockhoe14er said:


> wow that looks so professional. How difficult is it to wire the knobs to the ammeters? Does this require calibration or is it when the know is all the way to the right it's at 100% and when it's all the way to the left it's 0%?


The dimmer circuit in the Meanwell drivers works by giving a current that is proportional to the voltage across two wires out of the driver. The voltage across those wires has to be 10 volts maximum. So, you use a 10 volt DC converter, with that connected across the outer terminals on a 10,000 ohm potentiometer. Then the wires from the driver go to the 0 volt end of the potentiometer and to the middle terminal on the potentiometer, so turning the shaft clockwise increases the resistance (voltage) between those two terminals. It sounds a lot harder than it is. 

Then the digital ammeter also has 10 volts DC on the backlight circuit, from the same 10 VDC converter, and the two current measuring wires from the ammeter connect in the circuit to the LEDs, so all of the LED current flows through the potentiometer. That way the ammeter readiing is the LED current.

I will set the light up, and measure the PAR I get at 3-4 different currents, plot those data points to get a calibration curve for the light, showing PAR vs current. I have two colors of LEDs, neutral white and cool white, so I will have a calibration curve for each color. And, each chart will have the PAR vs current curve for probably 4 different heights of the light from the PAR meter sensor. Since the PARs add together, you can set the color of the light to suit you, then adjust the two currents to maintain that color, but at the PAR that you want at the substrate.

There are 3 blue LEDs, which have a separate power cord, so they can be on a different timer, for moonlight, and/or to add some more blue to the daytime light. Those will probably add a tiny bit of PAR, so can be ignored when figuring how much PAR you have.

This is the first time I have attempted to make a PAR calibrated light, so who knows how well it will actually work out.


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## Rockhoe14er (Jan 19, 2011)

wow that sounds kind of complex. But long story short are you attaching 

the dim-able wires on the meanwell driver ----->to a potentiometer------->knobs----> to ammeter?


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## Hoppy (Dec 24, 2005)

Rockhoe14er said:


> wow that sounds kind of complex. But long story short are you attaching
> 
> the dim-able wires on the meanwell driver ----->to a potentiometer------->knobs----> to ammeter?


No, it is a bit more complicated than that - the wires have to go to the right places, matching the positive and negative voltages as marked on the various parts. If you understand electric circuits, and use of a potentiometer as a voltage divider, it is very simple. If you don't, it would be difficult.

Now, a question: has anyone been soldering LEDs with an ungrounded soldering iron? I have a grounded one and a little higher wattage one that isn't grounded. I would prefer to use the ungrounded one, but have been using only the grounded one on LEDs. I can't see a reason why it needs to be grounded for that use.


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## IWANNAGOFAST (Jan 14, 2008)

mine is ungrounded. I think? It only has 2 prongs on the plug vs 3.


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## reybie (Jun 7, 2007)

Radioshack soldering iron here, only 2 prongs and no shocks that I remember


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## audioaficionado (Apr 19, 2011)

Hoppy, Cree has a pdf doc on their site called Soldering & Handling CLD-AP54 REV 0.

I don't know if you've read it yet, but I didn't find any warnings about ESD handling issues.

So I think your ungrounded iron should be fine.


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## Hoppy (Dec 24, 2005)

Ungrounded it is! Thanks to all of you.


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## redfishsc (Aug 29, 2010)

+1 I use the Radioshack $8 wonder and it works just fine.


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## Lakehouse (May 13, 2009)

:biggrin: looks AWESOME!!! roud:


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## sns26 (Mar 29, 2010)

Hoppy said:


> I will set the light up, and measure the PAR I get at 3-4 different currents, plot those data points to get a calibration curve for the light, showing PAR vs current. I have two colors of LEDs, neutral white and cool white, so I will have a calibration curve for each color.


I want to do something similar to this. Putting aside the fact that I don't have a PAR meter, my question is this: does PAR work purely additively? In other words, let's say you know the PAR that one string is giving you all on its own at a given dimming level, and the PAR that another string is giving you all on its own at a given dimming level. Can you just add those two PAR numbers together to get your total PAR for running both strings at those dimming levels at the same time?


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## Hoppy (Dec 24, 2005)

sns26 said:


> I want to do something similar to this. Putting aside the fact that I don't have a PAR meter, my question is this: does PAR work purely additively? In other words, let's say you know the PAR that one string is giving you all on its own at a given dimming level, and the PAR that another string is giving you all on its own at a given dimming level. Can you just add those two PAR numbers together to get your total PAR for running both strings at those dimming levels at the same time?


Yes, you can do that, assuming the two PAR readings were at the same spot in the aquarium.


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## cggorman (May 9, 2009)

Glad I found this thread. I'm in the middle of a similarly ambitious fixture build... nice to see I'm not the only one spending multiple hundreds of hours on calculations, spectrum data comparison, product selection, fabrication, etc...


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## Hoppy (Dec 24, 2005)

Progress Report: None! My LEDs haven't even arrived at ledgroupbuy yet, as of yesterday. I knew it takes time to receive an order from them but my impatience is growing.


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## audioaficionado (Apr 19, 2011)

Well now that we've seen how ledgroupbuy works, when I decide to get my LED project started, the LEDs will be the first thing I order even if I have to wait another month to afford the rest of the parts.


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## Hoppy (Dec 24, 2005)

I believe we get a great price through ledgroupbuy, but it is true that you have to be resigned to waiting longer for them to arrive than you hoped for. I don't regret my order.


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## redfishsc (Aug 29, 2010)

Yeah they're good folks but the lower price comes only with patience. Definitely order them early. I wish they carried some good drivers.


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## IWANNAGOFAST (Jan 14, 2008)

oh man, I must've been super lucky. My order from ledgroupbuy shipped almost immediately. I was super confused when they came because the group buy wasn't over for another 2 weeks. The guy told me they had some extras lying around so they sent em.


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## mikeyfish (Sep 7, 2010)

I'm waiting for leds from them right now as well. My order went in on may 7th but still awaiting fulfillment. I am kind of wondering that if when a group buy ends and there isn't a big enough order if it has to wait until there is a big enough order.


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## Lakehouse (May 13, 2009)

Any updates?


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## Hoppy (Dec 24, 2005)

Lakehouse said:


> Any updates?


 :icon_cry:


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## Hoppy (Dec 24, 2005)

No LEDs yet, so I have been working on how to use this fixture to make designing other LED lights easier. I started a thread in the lighting forum on that. Based on that very crude, so far, analysis, this light should do way better than I expected: about 350 mms of PAR maximum, at a 4 foot distance, and 40 mms of PAR with only about 200 mAmps of LED current. See: http://www.plantedtank.net/forums/lighting/138628-effect-optics-led-light.html#post1406799


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## Hoppy (Dec 24, 2005)

Oh happy day!!!










And, the order has been mailed Priority Mail! I should have them about Wednesday.


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## Lakehouse (May 13, 2009)

they take FOREVER to ship!


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## Hoppy (Dec 24, 2005)

The good news is the package arrived yesterday. That isn't exactly "FOREVER to ship". But, the bad news was that most of the optics were not in the package. And, finally, the good news again. I should get those in a week or so, so the delay will be minimal.

I hope today to get the LEDs cemented down, so I can start soldering tomorrow. 

XM-L LEDs have absurdly small emitters - almost microscopic compared to other LEDs I've seen.


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## Lakehouse (May 13, 2009)

i guess not forever to ship, just meant it seems like a long time from when the order was placed till it actually arrives. 
anyway, that is good news.....cant wait to see pics!


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## audioaficionado (Apr 19, 2011)

Hoppy said:


> ...XM-L LEDs have absurdly small emitters - almost microscopic compared to other LEDs I've seen.


And yet they put out 2-3x the light of other 3W LEDs.


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## Hoppy (Dec 24, 2005)

All LEDs cemented in place, using Arctic Silver Alumina Thermal Adhesive. There are 3 blue LEDs for moonlight, and 24 main XM-L LEDs. Tomorrow I heat up the soldering iron.


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## redfishsc (Aug 29, 2010)

Nice, can't wait to see it.


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## cggorman (May 9, 2009)

Holy crap, you solder those in place?! You use a 100 Watt iron?

Regarding size, what are you used to? They look about right for high output diodes... you should see the Luxeon Rebels. Talk about tiny. Sheesh. The primary optic is the size of a small pin head.


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## Hoppy (Dec 24, 2005)

Yes, I can't see any way to solder the leads on except with the LEDs mounted in place. The ones I have soldered before I used a 15 watt iron, but I plan to try a 30 watt one this time. The 15 watt was marginal.

The last LEDs I used were Ebay specials.


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## audioaficionado (Apr 19, 2011)

With all that heatsinking you'll need a lot more than a 30W iron. It couldn't take more than a couple of seconds. If it does, then you need more power.


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## cggorman (May 9, 2009)

The last three fixtures I built all used threaded heatsinks, so I put a doubled-over piece of construction paper between the sink and the star and held it loosely in place with screws. After soldering, I removed the stars and paper one at a time, applied thermal grease, and torqued.

First fixture was with a cheap radio shack 40 watt iron. Worked, but not ideal. All subsequent testing and builds used a Weller WES51 (50 watt, thermostatically controlled). That thing is the BOMB. Well worth the money if you do any real soldering. A friend and I do a lot of computer and electronics tinkering as well as radio control projects, so we share it.


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## Hoppy (Dec 24, 2005)

audioaficionado said:


> With all that heatsinking you'll need a lot more than a 30W iron. It couldn't take more than a couple of seconds. If it does, then you need more power.


The 30 watt Radioshack iron works great. It isn't temperature controlled, so it does tend to overheat a bit, but for the money and the rare times I need one, it works very well.


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## redfishsc (Aug 29, 2010)

Yeah I use the ratshack 40w and it's great for what I do. I just let it warm up for 20 minutes or so before using it. 


I just changed my 10g out (temporarily) from the single 10w LED to four cool white XML's at 1,000mA and MAN what a drastic amount more light than the 10w Satistronics LED. They consume a bit more energy (12w instead of 10w) but the light output, to the human eye, is drastically higher (higher efficiency). 

I will be converting this particular 4-XML array into a reading lamp soon  and I have the LED array done for my two upcoming builds. One more week


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## Hoppy (Dec 24, 2005)

It's done, or it should be. After I finished the wiring I plugged it in. The blue moonlights work fine, but none of the other LEDs light up.:icon_conf

So, the troubleshooting starts. First: Is it a mistake to tie all of the zero DC voltage lines together - one zero volt wire from the control box to the light fixture?

One possibility, which I was very careful to avoid, is reversed positive and negative wires. Another is a problem in the dimmer circuits, leaving the dimming voltage at zero. I did verify that I have a good connection at each LED solder pad. Tomorrow I will start troubleshooting.

Another question: Does it harm the drivers to run them with nothing connected to the output wires?


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## audioaficionado (Apr 19, 2011)

Did you adjust the 10v drive current setting pot in the drivers? It might be set to zero.

I don't see a problem with a common ground or return line as long as the polarities are all correct.


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## Hoppy (Dec 24, 2005)

For troubleshooting purposes it would help a lot to be able to run the drivers with no LEDs connected. Is that going to harm the drivers or would it give weird voltage readings?

I will check the current setting pot on the drivers, but I would expect possibly one to be set to zero, but not both.


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## jcgd (Feb 18, 2004)

I would think that running the drivers with nothing connected would be fine. There is no load, so there would be no current but you would still have a potential voltage across the lines.

I can't be sure, but it should be like taking a t5 bulb out and metering across the tombstones.

Does your meter have a diode test on it? I don't know about cheaper models, but any quality fluke model usually does. It usually shares a spot with the continuity test. If the polarity of the leads is backwards you will have no continuity and if its correct it will show the forward voltage and continuity I believe. Usually around 1V for a typical diode, not sure about the LEDs.

Also, all the negatives should be fine connected to a common ground. The ground is all the same spot after all and if you isolate one of them, it isn't grounded anymore.


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## jcgd (Feb 18, 2004)

Hoppy said:


> Another is a problem in the dimmer circuits, leaving the dimming voltage at zero. I did verify that I have a good connection at each LED solder pad. Tomorrow I will start troubleshooting.[QUOTE/]
> 
> 
> So you didn't apply a voltage to the dimmer circuit at all? Just to be clear, you didn't apply anything at all to the 0-10V circuit that controls the dimming of the driver? If you didn't apply anything at all the driver will stay off, dimming the LED circuit to 0%. You need to at least give it something. I would try hooking up a phone charger or something around 9VDC. And a low current... don't go nuts.


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## Hoppy (Dec 24, 2005)

I ran the pots from minimum to maximum with no effect - no current on the ammeters, and the LEDs didn't even glow. I'm trying to imagine an open connection that could affect both of them that way. This is how everything is wired, except that the negative leads are together in the fixture and in the power box, with a single wire connecting them, from power box to fixture. Note that I am not grounding anything.


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## audioaficionado (Apr 19, 2011)

Hoppy said:


> For troubleshooting purposes it would help a lot to be able to run the drivers with no LEDs connected. Is that going to harm the drivers or would it give weird voltage readings?
> 
> I will check the current setting pot on the drivers, but I would expect possibly one to be set to zero, but not both.


I wouldn't run the drivers unloaded unless you find something to the contrary in the spec sheet pdf.

Since those meanwells can run up to 60V @1200ma you can figure out what load resistance will mimic the maximum number of LEDs you can drive and make a dummy load to simulate. 
60v x 1.2a = 72W
I^2 x R = W
72W / 1.2a / 1.2a = 50 Ohms
Just string enough power resistors in series until they exceed 50 Ohms and 72 Watts.
But you already knew this didn't you?


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## jcgd (Feb 18, 2004)

How are the ammeters wired? I'm not sure by the wiring diagram. The ammeter is in series right? What is the negative going to the ammeter for?


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## Hoppy (Dec 24, 2005)

justincgdick said:


> How are the ammeters wired? I'm not sure by the wiring diagram. The ammeter is in series right? What is the negative going to the ammeter for?


The ammeters have a 10 volt DC power supply to light up the display. They share the 10 volt supply with the dimmer circuits for the LED drivers.


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## Hoppy (Dec 24, 2005)

audioaficionado said:


> I wouldn't run the drivers unloaded unless you find something to the contrary in the spec sheet pdf.
> 
> Since those meanwells can run up to 60V @1200ma you can figure out what load resistance will mimic the maximum number of LEDs you can drive and make a dummy load to simulate.
> 60v x 1.2a = 72W
> ...


Yes, I knew I could hook up a string of resistors to test the driver, but that is hardly an easy or cheap test. The more I think about this the more certain I am that it is ok to run the driver with an open output circuit. It is over voltage protected, and can be adjusted to run at zero amps. Also, if an LED fails, which has happened with my other Meanwell driven light, it opens the circuit. The incident didn't harm the driver as far as I can tell. 

Unless someone knows of a problem it will cause I plan tomorrow to disconnect the light fixture and trouble shoot that way. It will be a few minutes only anyway.


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## redfishsc (Aug 29, 2010)

Several thoughts. 


1) My Meanwells often took several seconds (up to 5-10 seconds) to spool up for the first time and I have no idea why. I always wound up unplugging them and plugging them back in a time or two. I don't know that all 4 of them did this but I know for sure 2 of mine did. You probably did this already but it's worth mentioning. 


2) Double-check that there is at least some voltage going into the dimmer circuit. A 9v battery is really good for this . 


3) I have, for a few seconds, run mine with no load, checking for voltage ONLY. Not for current. They should spool up directly to 48.1v or so. But you're right. I've had them blow an LED with an open circuit and it sat there for hours, and no harm done when I found it. Still runs well today.


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## Hoppy (Dec 24, 2005)

The problem is the ammeters. When I bypass an ammeter, the LEDs light up. Also, when I first plugged it in the ammeters read 1, which the instructions say means they are subjected to a current beyond their range, which is 2 amps. But, the Meanwell drivers only go to 1.3 amps. Now what? I really need the ammeters unless I use a dial on each pot for setting the PAR outputs. Bummer!

In the garbled English instructions for the ammeters, it says not to use more than one meter on a power supply - or it says not to us more than two meters, voltmeter and ammeter on one power supply. I wonder if there is a problem wiring the DC supply to the meters ( the 10 volts for the backlight ) in parallel to two ammeters. I can't see how that would be a problem.


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## HolyAngel (Oct 18, 2010)

Sounds/looks right to me that it wouldn't work..maybe Not enough volts if they both require it much less them and the the moonlights.. The problem definitely looks like its between the ammeters, the dc psu, and the moonlight driver, according to your schematic.. Looks like too many things drawing from the same power source at different currents and/or volts to me but the problem could specifically be somewhere else, but it's definitely something with that setup there for the ammeters.


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## jcgd (Feb 18, 2004)

I can only assume you have, but did you disconnect one ammeter from the 10v supply and see if the other works by itself? I can't see why it would matter though, if it's paralleled. How would the meter know?

Do you have a link for the ammeters or anything? I'm curious about them and want to read up.


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## jcgd (Feb 18, 2004)

HolyAngel said:


> Sounds/looks right to me that it wouldn't work..maybe Not enough volts if they both require it much less them and the the moonlights.. The problem definitely looks like its between the ammeters, the dc psu, and the moonlight driver, according to your schematic.. Looks like too many things drawing from the same power source at different currents and/or volts to me but the problem could specifically be somewhere else, but it's definitely something with that setup there for the ammeters.


Keep in mine with Hoppy's wiring diagram that wires cross but do not connect. The 10v supply feeding the pots and the ammeters shouldn't matter if everything is paralleled (which it is) as long as the supply can put out the total current the devices draw, which should be very low anyway.

In parallel everything is getting 10v.


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## Hoppy (Dec 24, 2005)

The two pots are 10,000 ohm resistors, which draw 1 mAmp each, and the ammeters draws 50 mAmps each, as I recall. That may be more than the little 10 VDC adapter can supply, but I doubt it. The ammeters are wired in series with the power to the LEDs, so I can't see how they can stop the current flow, which I assume just goes through a low resistance resistor, so the meter can read the voltage drop on it. But, they sure do stop the current.

Now, I'm thinking I should just use dials and calibrate by the dial position. It won't be as precise as I expected, but it should work. Then I will need to plug the holes for the ammeters in my box.

Here is some stuff on the ammeters: http://tinyurl.com/3qmuax3


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## HolyAngel (Oct 18, 2010)

Ah yeah you're right I see. Was thinking amp/current. *sheepish*

What about the dimmer switch's? Do they need dc power? They're both linked off te same leads as the ammeters, which looks like it would make an open system.. Unless they do need power.. But otherwise maybe that's the problem? They should be able to control everything off the lines from the drivers themselves and that way the ammeter would work correctly.. That's about all I got at this point..


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## jcgd (Feb 18, 2004)

Inrush current? If you don't mind and have the supplies, put the meter inline with a switch, or something you can use as a disconnect, turn on the array and then disconnect the bypass ---> the inrush current can bypass the meter and then you can switch over to the meter without disconnecting the circuit.

I dunno if it'll work, but that may be the problem. If it is, you just set it up so you 'turn on' the meter just to set the current with a couple switches.

I looked at the meanwell spec sheet and it only noted an inrush current on the line side, but I can't determine it the load side would have one as well. I would assume it wouldn't, but I can't be sure.

The only other option I could think of would be using voltmeters on the pot instead. If you figure out what current the driver puts out at what voltage, you should be able to achieve the same goal I would think.


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## Hoppy (Dec 24, 2005)

Inrush current could be a problem, but it if is, the only way out would be a normally closed switch that bypasses the ammeters, and opens to let the current flow through the ammeters. That is a possibility, but I hate to go to all of that trouble only to have it still not work. I may have damaged the ammeters by now. I plan to buy another project box and either use the cover from that to replace the one with the ammeters in it, or just use the new box, a real pain to do.

Right now, some more thinking is called for.

Do LED circuits experience an inrush current? In other words, is the voltage drop low at start up, then rising to the equilibrium value? Or does the Meanwell driver prevent that, being a constant current device? Days like this are when you realize that what you don't know far exceeds what you do know.:biggrin:

Using digital voltmeters instead of ammeters wouldn't work (I think), unless you wired them so they acted as ammeters, measuring the voltage drop across a resistor. That's getting too complicated.

The two little knobs on the pots have a stripe on them, so that would allow using that stripe as a pointer on a dial to set the current. It would be crude, but might be good enough to do the job.


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## jcgd (Feb 18, 2004)

Hoppy said:


> That is a possibility, but I hate to go to all of that trouble only to have it still not work. I may have damaged the ammeters by now. I plan to buy another project box and either use the cover from that to replace the one with the ammeters in it, or just use the new box, a real pain to do.


You could do a scab job to test it, just add two pieces of wire and marrette them, and pull the splice off to try it.



Hoppy said:


> Right now, some more thinking is called for.
> 
> Do LED circuits experience an inrush current? In other words, is the voltage drop low at start up, then rising to the equilibrium value? Or does the Meanwell driver prevent that, being a constant current device? Days like this are when you realize that what you don't know far exceeds what you do know.:biggrin:


I can't help you here, as I don't know. I'm leaning towards no inrush because you would have a flash when you start up your LEDs, but I can't be sure of this. It was just a thought I had.



Hoppy said:


> Using digital voltmeters instead of ammeters wouldn't work (I think), unless you wired them so they acted as ammeters, measuring the voltage drop across a resistor. That's getting too complicated.


I can't see why you couldn't put a voltmeter across the output and negative of the pot, or whatever teminals you use to power the dimmer circuit. I mean, read the variable voltage coming from the pot, the 0-10v. Theoretically, if the voltage was say 5v, the current would be at 50% and you could have the par measured for that setting. It would just make tuning to pots quick. If the drivers are any good, the output current should be fairly accurate according to the applied voltage to the dimmer circuit.

I'm thinking that if 50% of you LED circuit current was 500ma and you use your ammeter to read that, your pot should be putting out 5v. So whether you read the LED string's current or the pots output voltage (or dimmer input, same thing) should not make a difference assuming the driver is accurate.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> I can't see why you couldn't put a voltmeter across the output and negative of the pot, or whatever teminals you use to power the dimmer circuit. I mean, read the variable voltage coming from the pot, the 0-10v. Theoretically, if the voltage was say 5v, the current would be at 50% and you could have the par measured for that setting. It would just make tuning to pots quick. If the drivers are any good, the output current should be fairly accurate according to the applied voltage to the dimmer circuit.
> 
> I'm thinking that if 50% of you LED circuit current was 500ma and you use your ammeter to read that, your pot should be putting out 5v. So whether you read the LED string's current or the pots output voltage (or dimmer input, same thing) should not make a difference assuming the driver is accurate.


You are right, that would work. I'm thinking that it would work equally well to just use a dial on the dimmer knobs, because they are linear pots, and the output voltage from them should be directly proportional to the amount of rotation of the pots. And, dials don't short circuit, go open circuit, or emit smoke at inopportune times.:biggrin:

Actually, for the user of the light, the current through the LEDs is irrelevant. It is the light output that counts, and that can just as well be calibrated against knob position as against current. For my other purposes I would much prefer to know the current, but I can work around that. (My other purposes are to find a method for calculating PAR for a LED light, knowing just the lumen output of one LED and the design details. This was to be my research tool.)


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## fishykid1 (Apr 5, 2010)

Hoppy said:


> I'm hoping that with 1300 mAmps the light will be high light, so when dimmed, and the color adjusted, it will be 40-50 mms of PAR. The 3 moonlight LEDs will have their own 350 mAmp driver, not adjustable, but also not very bright at that distance, with 60 degree optics. I think I would leave the moonlights running along with the other LEDs, to add some blue for better color in the fish.
> 
> I have the heatsink and aluminum channels screwed together now. I used a flat sanding block to flatten the mating surfaces, and used some heatsink grease between them for better heat transfer. Now, I'm struggling with installing the hanging kit, from RapidLed - as they noted, it doesn't fit well between fins on the heatsink I have. It only lacks about 1/32 inch of making it, so a small rotary file should make room.


Hoppy, are you still running these at 1300 mA? Run them at 700-900mA and you'll have less heat and still a good amount of light. If your using the Meanwell ELN-60-48D as drivers, then it'll be easy to measure the current and keep it slightly lower.


NEVERMIND: I forgot you were using the Xm-L but even still you could run them lower...and they'd be fine.


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## audioaficionado (Apr 19, 2011)

I also have a cacti collection. I wonder how much PAR I'll need for those to be happy? I figure reef levels should do it. Looks like I'll also need some LED love for my carnivorous plant collection I'm going to start.

LED's are amazing once you figure out the cone spread and the PAR levels.


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## Hoppy (Dec 24, 2005)

fishykid1 said:


> Hoppy, are you still running these at 1300 mA? Run them at 700-900mA and you'll have less heat and still a good amount of light. If your using the Meanwell ELN-60-48D as drivers, then it'll be easy to measure the current and keep it slightly lower.
> 
> 
> NEVERMIND: I forgot you were using the Xm-L but even still you could run them lower...and they'd be fine.


I'm expecting this to run at 200-500 mAmps, but that will be determined when I test the light - assuming I finally get it working right.


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## fishykid1 (Apr 5, 2010)

Hoppy said:


> I'm expecting this to run at 200-500 mAmps, but that will be determined when I test the light - assuming I finally get it working right.


What's going wrong with it now? 200 mA on the xml may be barely using the light. Why not just run the XPG and run them at 500mA. They'd push out around 120 lumens.


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## audioaficionado (Apr 19, 2011)

XM-Ls are brighter than the XM-Gs with the same current.


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## jcgd (Feb 18, 2004)

fishykid1 said:


> What's going wrong with it now? 200 mA on the xml may be barely using the light. Why not just run the XPG and run them at 500mA. They'd push out around 120 lumens.


At the same time, why not? The XML wont limit you and the greater cost per LED is offset by less total LEDs needed. And the fixture will never not have enough power. Not to mention even less energy used.


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## Hoppy (Dec 24, 2005)

Since the light is now assembled, and I can't be sure how much PAR I will get until I do the testing, it would make little sense to replace the LEDs. My predictions for how much PAR I will get are just predictions, based on an extreme extrapolation of the data I already have.


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## redfishsc (Aug 29, 2010)

Hoppy said:


> Do LED circuits experience an inrush current? In other words, is the voltage drop low at start up, then rising to the equilibrium value? Or does the Meanwell driver prevent that, being a constant current device? Days like this are when you realize that what you don't know far exceeds what you do know.:biggrin:


This is a bit troublesome to me since I'm about to do the same thing you are..... My meters are 2.0A meters like yours. 

I know that Meanwells can have HUGE inrush currents on their AC input side, as (I believe) capacitors are charging, but that's only for a fraction of a second. As for the DC (LED power) side, I'm not totally sure.


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## Hoppy (Dec 24, 2005)

redfishsc said:


> This is a bit troublesome to me since I'm about to do the same thing you are..... My meters are 2.0A meters like yours.
> 
> I know that Meanwells can have HUGE inrush currents on their AC input side, as (I believe) capacitors are charging, but that's only for a fraction of a second. As for the DC (LED power) side, I'm not totally sure.


It is indeed troublesome. The first time those two ammeters I have were connected to power they failed to work. I still haven't found any mistakes in wiring, and the LEDs light up if the ammeters are shorted out of the circuit, so I have to wonder if the ammeters are really workable. I doubt that I will be buying any of them again.


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## redfishsc (Aug 29, 2010)

You don't perchance have the polarity reversed do you? It's distinctly possible that they were mislabeled. 

Also, is it at all possible your shunts are on backwards (sending the LED current through the wrong ammeter terminals)?


I do realize you're an engineer lol! Just trying to rule out the most obvious. I know all three of mine work, I've tested them.....even though they are still collecting dust for another week or two until I get the stain/clearcoat done on the stand and canopy.

Which ones did you buy (link)?


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## redfishsc (Aug 29, 2010)

Oh by the way. I found that if the ammeters are not given sufficient voltage (power for the backlight and such), they (mine) will read a "1". But, current flows freely through them, and does not obstruct the driver from working at all. 

You also mention that they haven't worked at all. It's very possible that they are NOT 9v operated but 12v. After you have ruled out "safer" things, try giving them 12v input (using a good, verified 12v input). I know my supplier said that he had them in 5, 9, and 12v. I got the 9v. 


Lastly, double check your max voltage rating on the meters...... (for the current being measured *through the LED array*, not the 9v input voltage). Mine have a max voltage of something quite close to the voltage of the Meanwell. It's either 48 or 50v, and yours may actually be lower than that. If so, that could have blown them.


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## Hoppy (Dec 24, 2005)

My embarrassment has no bounds!

After a lot more troubleshooting, I finally powered only the 10 VDC adapter that provides the dimming voltage, and powers the backlights on the ammeters, (after removing the ammeters), and:icon_redf:icon_redf I'm mortified.

I had the polarity reversed on the 10 VDC supply. Correcting that has the LEDs all lighting up properly and the dimmers working properly, and I don't doubt that the ammeters will also work properly when I hook them back up.

Excuse me while I go sit in a corner.


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## Lakehouse (May 13, 2009)

Woo-hoo!

Ps-don't be embarrassed! I've only been able to follow about half of this thread and I'm a mechanical engineer!( I guess that's why I never pursued electrical engineering) haha

Glad you figured it out


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## Hoppy (Dec 24, 2005)

All back together. Plugged in, all LEDs lit up, adjusted the pots to lower the current a bit. POP! it all went off. No burned smell, but it is dead for now - ammeters, LEDs, everything. I don't have any idea yet what failure can do that???

I'm starting to think it might be more fun wrestling bears.

EDIT: All LEDs check out ok, with a DIY LED tester. No LED is grounded to the heatsink. The 10 VDC adapter still produces 10 VCD, and the pots still divide that properly. But, the ammeter backlights don't come on, and the LEDs don't light.

Any ideas???

EDIT: I removed the ammeters again, and it works fine now. I have no idea what the problem with the ammeters is, but it isn't worth it to keep struggling with them. Even if I got it to work for now I would be concerned that when the guy I'm making this for gets it, they may act up again. Obviously these particular ammeters don't run the load current through an internal shunt, but through the electronics someway. Bummer, but at least they weren't expensive.

Now I need to modify or replace the project box so it doesn't have the big holes for the ammeters in it.


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## Hoppy (Dec 24, 2005)

This is the final electrical schematic I'm using:


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## jcgd (Feb 18, 2004)

Oh man. I got all excited when you said you got it working and then I read the next post and wham... Crush my dreams. That's too bad about the ammmeters. I decided to use them between your posts, but not now. 

Maybe redfish will figure it out and I can use them in the end.


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## Hoppy (Dec 24, 2005)

I keep thinking that there has to be a simple reason why the ammeters acted up, but I still can't think of one. They are multi-voltage, with anything from 9 to 12 or more volts being acceptable, which is why I decided to use 10 volts. And, normally an ammeter will allow the current to go through it even if it fails, because normally they work by measuring voltage drop across a low resistance resistor. These never did allow current to flow except for less than a minute, and I'm convinced that the POP I heard was that resistor failing (maybe). Maybe this is one more proof of the old adage - you get what you pay for.


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## jcgd (Feb 18, 2004)

Could be. You don't get much for a few bucks.

You've got me stumped as well. It just doesn't make sense. So what are you planning on doing now?


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## Hoppy (Dec 24, 2005)

justincgdick said:


> Could be. You don't get much for a few bucks.
> 
> You've got me stumped as well. It just doesn't make sense. So what are you planning on doing now?


I will continue without ammeters, using marked dials to calibrate the dimmers. Tomorrow I need to replace at least the cover to the project box, because of the big holes left from the ammeters. Perhaps Tuesday I can start calibrating the light, and, since I should get the optics Wednesday, I should be able to complete the calibration on Thursday.


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## jcgd (Feb 18, 2004)

Woot. I can hardly wait for you to test this baby out and get some par readings. I was hoping to jump on a LEDgroupbuy order before the current deadline expires, but between the info I'm hoping to get from you an inquiry on drivers from O2surplus I might miss the bus.

I'm actually gonna pm you some more questions about my build and some knew ideas I need to poke your brain with.


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## Hoppy (Dec 24, 2005)

I got it finished today, by replacing the cover on the project box, and adding a couple of 1 to 10 dials on the pots. Ready to test now, as soon as I get the PAR meter. Pics to be added later.


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## Rockhoe14er (Jan 19, 2011)

That stinks about the ammeter. Do you think it's because it's cheep that it didn't work?


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## Hoppy (Dec 24, 2005)

I still have no idea why the ammeters failed to work.

Here is the light, at near minimum power, with no optics:









And, here is the control box:









The dials were made with a graphics program on my Mac, printed on an address label, then sprayed with clear lacquer.


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## cggorman (May 9, 2009)

Looks nice and clean. Better than mine!


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## Rockhoe14er (Jan 19, 2011)

wow looks awesome


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## Hoppy (Dec 24, 2005)

The next question is likely to be, how much did it cost? Here is the cost breakdown.


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## IWANNAGOFAST (Jan 14, 2008)

Looks good, can't wait for par readings, I have some plans for big tanks but haven't built any and don't want to under do it. 

Btw, sorry if I missed this but what's the spacing on the white LEDs?


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## Hoppy (Dec 24, 2005)

The LEDs are spaced about 2.63" apart and the rows are 2.25" apart. One row is Neutral White, and the other row is Cool White. It appears that the minimum current that will keep the LEDs lit is about 350 mAmps. I'm surprised by that, the specs have a graph of current vs output and vs voltage drop that suggests that 200 mA is the minimum. It's possible that I could adjust the output voltage of the drivers a bit higher and lower that minimum current.


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## redfishsc (Aug 29, 2010)

Hoppy, there is a note with my ammeters ( a different brand than yours) that says specifically that the working power and the measured power cannot use a common ground. 

I'm not sure if that has anything to do with your setup, mine won't be grounded (the 9v DC supply has no ground).


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## Hoppy (Dec 24, 2005)

I have no ground either, just a common zero volts line from the drivers to the LEDs. The ammeters were in the positive voltage line to the LEDs.

Another possible problem: I have two different kinds of optics. One is for the XM-L and one for the XP-E (Not XR-E, as I thought) Which is for which LEDs??

















Both can fit either LED, but the tiny one "snaps" onto the XM-L LEDs, and the other one has to be attached with adhesive to either LED


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## redfishsc (Aug 29, 2010)

XPE is the one with the white housing. 

I'm actually quite shocked that the white ones fit an XML. I have some sitting around from ledgroupbuy, I'll see if the pop right on my XML's. 

Use silicone or bathroom caulk as the adhesive. Strong enough, but easily removed in the future. I glued some on with "bob smith" standard epoxy from Lowes, and they were a bugger to remove.


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## Hoppy (Dec 24, 2005)

I'm also waiting for Milad to look at the pics and say which is which. You would think those little things, as small as they are, would have a part number of some kind on them. The small ones fit on the XM-L by gripping the lens/junction cover. But the big ones would have to be stuck on with silicone. What I didn't mention is if the little ones are the XM-L ones, they are 40 degree, while the other would then be 60 degree.


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## jcgd (Feb 18, 2004)

Would it be easy enough to just place each lense over a RB and hold a board above them to see the size of the cone? I only say the royal blues because if I remember correctly you had less of them spaced further apart.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> Would it be easy enough to just place each lense over a RB and hold a board above them to see the size of the cone? I only say the royal blues because if I remember correctly you had less of them spaced further apart.


Yes, that could be a good test, but its tricky to do anything around a LED light that is lit up. You can blind yourself quickly, and you can't see what you are doing. The blues don't have a dimmer, so I would need more hands to do the test. First I will wait to see what Milad says.

I picked up the PAR meter tonight, so tomorrow I will be testing the light without optics.


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## redfishsc (Aug 29, 2010)

Unless Milad has started carrying different XP optics than he did two months ago, I'm 100% certain the white one is the XPE optic. 

It would not be unusual at all for the XML optic to need adhesive, that's the case with many reflectors and optics.


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## Hoppy (Dec 24, 2005)

Redfish, you are right. Milad accidentally sent me 20+ of the XP optics instead of the XM ones. So, now we need to correct the numbers - another couple of days delay. It's a good thing I didn't install the white ones on the XM-L LEDs. And, they fit so nicely too.


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## cggorman (May 9, 2009)

redfishsc said:


> XPE is the one with the white housing.
> 
> I'm actually quite shocked that the white ones fit an XML. I have some sitting around from ledgroupbuy, I'll see if the pop right on my XML's.
> 
> Use silicone or bathroom caulk as the adhesive. Strong enough, but easily removed in the future. I glued some on with "bob smith" standard epoxy from Lowes, and they were a bugger to remove.


 
Hot glue is MUCH faster and still removeable. roud:


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## HolyAngel (Oct 18, 2010)

Why do the pots need 10v power? Thought they were knobs that dim according to mechanical/electrical resistance. I still think the ammeters need their own power that not tied in to the pots and it'd work.. The schematic looks like you had 3 circuits on that one 10v dc, both pots and the ammeters.. Which won't work. The dc has to be a closed circuit, juctioning it to the pots seemed to me to be the issue.. But again.. Idk wth these 'pots' look like an how they hook up according to your schematic..

Anyways though, regardless of that, this is looking like its come together really well, I'm really interested in the par readings ^^


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## cggorman (May 9, 2009)

It's not technically the pots that need the 10v. It's the driver's dimmer circuit. if the circuit sees 10v, the driver outputs 100%. If the circuit sees 5v, the driver outputs 50%...etc. The dimming circuit won't safely accept more than 10v.


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## jcgd (Feb 18, 2004)

The 10v the pots receive is the voltage the pots dim and send to the dimmer circuit.


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## Hoppy (Dec 24, 2005)

I finished testing the light minus the optics, this afternoon. It impressed me! With both the neutral white and cool white LEDs on, at full current, 1300 mAmps, I got 28 mms of PAR at *54 inches* distance. That would be 18 inches above the top of the 36 inch high tank this is for. No optics! With the 40 degree optics it may be too bright to be dimmed adequately.

Here is some of the data I got today, plotted on log-log graph paper:


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## cggorman (May 9, 2009)

I really need to find a PAR meter...


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## Hoppy (Dec 24, 2005)

The Cool White LEDs I have are bin T6, which is rated at 280 lumens at 700 mAmps, and the Neutral White LEDs are bin T5. rated at 260 lumens at 700 mAmps. But, the Neutral White ones give more PAR than the Cool White, once again demonstrating the problem with using lumens when looking for PAR. This will make using lumen ratings to calculate the expected PAR good only for rough estimates.

The 3 blue XP-E, for moonlights, gave 4 mms of PAR at 24 inches distance, with no optics. I think they will work out ok at the 54 inch or so height of the light fixture, using 60 degree optics. The greater height should drop the par to about .8 mms, and the 60 degree optics should increase that to about 3 mms. That may be too bright, but it sure won't grow plants. The light from those sure looks white to me.


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## jcgd (Feb 18, 2004)

So you used blue XP-E, not royal blue? 

Any idea why the neutral white put out more par, scientifically speaking. Is it something to do with spectrum or anything like that?


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## Hoppy (Dec 24, 2005)

I don't know why the difference in PAR/lumens for the two very similar LEDs. It could be the spectrum or it could be the efficiency of the different phosphors used in the LEDs. Or, something else.


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## cggorman (May 9, 2009)

I would guess the neutral white's broader spectrum is why it shows higher PAR. It emits more in the red end and less in the blue. Most cool-white LEDs are biased extremely heavily in the 450nm range in order to maximize lumen output...at the expense of CRI (and PAR).


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## cggorman (May 9, 2009)

I don't have complete data for Cree, but this is a graph comparing spectral power distribution of the three whites from LedEngin along with a trace of the D6500K standard.


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## Hoppy (Dec 24, 2005)

Interesting, but what is the D6500K standard? Standard for what, by whom?


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## cggorman (May 9, 2009)

I believe that's a CIE standard.


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## Tbakes (Mar 16, 2011)

Hoppy - I'm about to start a similar build and would like more details on your wiring (e.g. awg for each run) and the DIN connectors and multi-conductor cables you used. Do you have some detailed photos other than what you posted? 

I promise to repay in kind by posting the details on my Typhoon-controller based build in the coming weeks.

Thanks!


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## cggorman (May 9, 2009)

Yep. CIE. http://en.wikipedia.org/wiki/Illuminant_D65 I added the "00k" at the end in an attempt to make it easier to identify that trace as an approximation of daylight. (Perhaps I've spent way too much time researching display calibration)


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## O2surplus (Jan 31, 2010)

Tbakes said:


> Hoppy - I'm about to start a similar build and would like more details on your wiring (e.g. awg for each run) and the DIN connectors and multi-conductor cables you used. Do you have some detailed photos other than what you posted?
> 
> I promise to repay in kind by posting the details on my Typhoon-controller based build in the coming weeks.
> 
> Thanks!


Uh- I'm gonna subscribe early to this one.:biggrin:


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## Hoppy (Dec 24, 2005)

cggorman said:


> Yep. CIE. http://en.wikipedia.org/wiki/Illuminant_D65 I added the "00k" at the end in an attempt to make it easier to identify that trace as an approximation of daylight. (Perhaps I've spent way too much time researching display calibration)


Thank you! That is a great reference, and the little video illustration of the different color temperatures is fascinating too. Chromaticity is discussed there too, something specified for at least Cree LEDs.


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## Hoppy (Dec 24, 2005)

Tbakes said:


> Hoppy - I'm about to start a similar build and would like more details on your wiring (e.g. awg for each run) and the DIN connectors and multi-conductor cables you used. Do you have some detailed photos other than what you posted?
> 
> I promise to repay in kind by posting the details on my Typhoon-controller based build in the coming weeks.
> 
> Thanks!


Here is the last wiring schematic I made, and as far as I can see, it is accurate:










All of the wiring, except the connecting cable is black insulated 22 gauge twisted wire. The connecting cable is a 4 conductor flexible cable, also 22 gauge wire from a local electronic hobbyist supply store. The DIN connectors are just what I found on the display rack at that same store, 4 conductor male cable end connector, and female chassis connector (it should be the reverse, but I changed design in mid-stream).

I didn't want a 6-7 conductor cable because it gets pretty stiff for that size, with that gauge wires, so I combined all of the zero voltage leads to the LEDs into one lead, and omitted any grounding, so I only needed 4 conductors.


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## jcgd (Feb 18, 2004)

Can I ask why you decided to go with XML instead of XPG. I was doing some comparisons and XPG are around 25% cheaper, lumen/$ at 1000mA. And that isn't factoring in optics. It seems that XPG would be cheaper overall for the same result. 

I guess I'm just asking, why should I choose XML over XPG?


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## cggorman (May 9, 2009)

I didn't know you could combine the (-) leads from different drivers. My cable to the fixture is 10 conductors...and yeah...too fat and stiff.

I also never considered a round DIN connector. I didn't think they were rated for 1.5A @ 48v, so I used molex-style.

Yours is much cleaner.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> Can I ask why you decided to go with XML instead of XPG. I was doing some comparisons and XPG are around 25% cheaper, lumen/$ at 1000mA. And that isn't factoring in optics. It seems that XPG would be cheaper overall for the same result.
> 
> I guess I'm just asking, why should I choose XML over XPG?


I planned to use XP-G LEDs but they were out of stock when I was ready to buy. Then I was also having doubts about being able to get enough light that far away, and didn't want to run any LED near its maximum current. So, the XM-L looked much more promising - it was available in the two colors I wanted, it would be at less that 50% of capability at the 1300 mA that the drivers could supply, and it had a better chance of giving the PAR I wanted.

Now it looks like they may be overkill, but I can't be sure until I get the optics and test it.



cggorman said:


> I didn't know you could combine the (-) leads from different drivers. My cable to the fixture is 10 conductors...and yeah...too fat and stiff.
> 
> I also never considered a round DIN connector. I didn't think they were rated for 1.5A @ 48v, so I used molex-style.
> 
> Yours is much cleaner.


I don't know that they are rated for that current and voltage, but they are certainly capable of handling it. The most probable current is about 400 mA, so the two combined return currents will probably be 800 mAmps - plus 350 mAmps for the moonlights.


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## Hoppy (Dec 24, 2005)

I can't keep the LEDs lit at any current below about 400 mAmps, but the Cree data PDF shows that it should work down to about 200 mAmps. Can this be because the output voltage of the drivers is set too low? I thought the voltage drop on LEDs went down with current, not up.


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## redfishsc (Aug 29, 2010)

I doubt it. The drivers are designed to automatically compensate for voltage drop as current drops. 


Is this happening on the XPEs as well, and happening consistently on the two different XML strings?


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## cggorman (May 9, 2009)

That's a limitation of the Meanwell driver. They clip below 15%...much to my dismay.:icon_mad:

As you've discovered, 15% brightness on these lighting-class diodes is still really bright.


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## audioaficionado (Apr 19, 2011)

So much for sunrise & sunset simulations with Meanwell drivers. Oh I guess they meant well :icon_neut


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## Hoppy (Dec 24, 2005)

cggorman said:


> That's a limitation of the Meanwell driver. They clip below 15%...much to my dismay.:icon_mad:
> 
> As you've discovered, 15% brightness on these lighting-class diodes is still really bright.


The rated current for the driver is 700 mAmps, or that is the current at which they give the lumen output, and the point on the lumens vs current curve called 100%. 15% of 1300 mA is about 200 mA, and I can't keep them going below about 400 mA. Something else must be happening.

I knew these LEDs are very bright, but I relied on the data in the Cree pdf which shows lumens vs LED current, and which goes down to less than 200 mAmps. I have to believe that Cree isn't fudging data, so there must be something else happening.



redfishsc said:


> I doubt it. The drivers are designed to automatically compensate for voltage drop as current drops.
> 
> Is this happening on the XPEs as well, and happening consistently on the two different XML strings?


The XPE's are on a fixed 350 mA driver, so they aren't affected. When I had a similar problem with my last LED light, which had closer to the maximum number of LEDs on the driver, I just adjusted the pot in the driver to a higher voltage output, and the problem went away. This light is acting like the other one - the LEDs light for a few seconds, then go off until I increase the current to them. It won't cost anything to try adjusting the voltage, so I plan to do that just in case it helps.

I'm going to be away from Saturday thru next Thursday, so it may be awhile before I get time to play with this.


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## audioaficionado (Apr 19, 2011)

Try bypassing a couple of LEDs with a shunt wire and see how it behaves with less LEDs in series.


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## cggorman (May 9, 2009)

200mA at what Vf and what voltage is the driver supplying? I can't honestly see that being the problem since the voltage trim pot is a limiter and the Vf @ 200mA can't be much, but who knows....

My ELN-60-48P shipped putting out [email protected] 56v. (Way over the rated max for both). I dialed it back to 1.2A but left the voltage at maximum since the driver actively manages it.

I've gotta say that so far I'm not terribly impressed with the Meanwells. Wondering if I should have gone with the Magtechs or Maxims


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## Hoppy (Dec 24, 2005)

Suppose I were to adjust the drivers down to 800 mAmps maximum. Would that also reduce the minimum current output proportionally? Of course if the problem is that the LEDs can't operate at low currents it wouldn't help.

I considered shunting out a LED, but I hate to tamper with it that way. That would certainly eliminate available voltage as a problem.


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## cggorman (May 9, 2009)

I believe it does, yes. When I was tinkering with mine, I believe I could get a lower minimum brightess as I turned down the current trimmer. In my case, it sacrificed too much at the high end, but it sounds like that's ok for you.


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## Hoppy (Dec 24, 2005)

cggorman said:


> I believe it does, yes. When I was tinkering with mine, I believe I could get a lower minimum brightess as I turned down the current trimmer. In my case, it sacrificed too much at the high end, but it sounds like that's ok for you.


That looks like the best bet for now. If I didn't have to get ready for the trip I'm going on I could try it right away. I need to set up the light with a PAR meter to do this well, and there are just too many other odd jobs to do first.

I really appreciate the help I'm getting from you guys. Without this forum I wouldn't dare try a DIY project like this.


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## audioaficionado (Apr 19, 2011)

I wonder if the PWM Meanwells have this issue?


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## cggorman (May 9, 2009)

I get the same results across all the following:

ELN-60-48P driving twelve 5W LEDs
ELN-30-27D driving six 5W LEDs
ELN-30-48D driving six 3W LEDs

During my testing phase, I was using resistors and pots to dial back a 200W computer power supply (dialing back a 5V leg to drive single LEDs) and I could dim them smoothly all the way to black (off).

Here is a copy of the Meanwell ELN series dimming graphs (from their published PDF) Looks like the Ds (that's what Hoppy is using, I believe) clip at 5%


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## redfishsc (Aug 29, 2010)

Hoppy said:


> Suppose I were to adjust the drivers down to 800 mAmps maximum. Would that also reduce the minimum current output proportionally? Of course if the problem is that the LEDs can't operate at low currents it wouldn't help.




I think you are right, Hoppy. I seem to recall having the driver cranked up to 1450mA for my XPGs once and they wouldn't dim all the way off, but if set at 990mA, they do dim all the way off if I drop the reference voltage.


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## Hoppy (Dec 24, 2005)

I'm very encouraged! When I get back to this I should be able to make it work. And, my drivers may be set at more than 1300 mA, since I have no convenient way to measure it, with the digital ammeters not working for me. And, I have no way of knowing what the current is since my digital ammeters don't work. I should be able to use the PAR meter to get to a good adjustment by interation - adjust, try to dim, readjust, try to dim, etc.


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## audioaficionado (Apr 19, 2011)

Well the nice thing about the XM-Ls is that you can't blow 'em with that Meanwell no matter what you set them at.


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## redfishsc (Aug 29, 2010)

Hoppy said:


> I'm very encouraged! When I get back to this I should be able to make it work. And, my drivers may be set at more than 1300 mA, since I have no convenient way to measure it, with the digital ammeters not working for me. And, I have no way of knowing what the current is since my digital ammeters don't work. I should be able to use the PAR meter to get to a good adjustment by interation - adjust, try to dim, readjust, try to dim, etc.


They may well be sitting at way higher, depending on how they came set from the factory. The ELN models can, sometimes, vary wildly. I've heard of them (from a retailer that stopped carrying them) showing up giving 1.5A and 700mA, varying one from the next. 

I haven't ever tested the "out of the box" amperage, I always turn it all the way down first, hook up the multimeter, and adjust it running. Works like a charm.


I just finished my stand and canopy (stain/clearcoat) for my tank yesterday, and it's ready to install.............. gonna be a fun weekend .


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## Rockhoe14er (Jan 19, 2011)

So i copied hoppy's wiring except i put my ammeter in series on the negative terminal of my LED lights instead of the positive side and everything works perfectly. I didn't have to change the max current on my Mean Well ELN-60-48D dimmable driver and I can get the lights to run from about .15 A to 1.4 A (according to my ammeter). I think you just got a bad ammeter. I have the exact same model that you got with pretty much identical wiring and it is working perfectly.

you can check out my LED build thread to see the finished project. All the wires are inside of the plastic box but the wiring is identical to hoppy's.


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## Hoppy (Dec 24, 2005)

I just got a month's reprieve on when the light is needed, so I may go back to trying to get the ammeters to work for me, too. Putting them on the negative side may be important - the instructions show it wired that way. For the next week, though, I will be away - in Georgia, in fact.


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## Rockhoe14er (Jan 19, 2011)

I did find out that they labeled it wrong when i hooked it up the way the instructions said i got a negative current so i had to switch the leads.


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## FDNY911 (Dec 6, 2009)

Subscribed ... Should have Subbed a while ago!


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## redfishsc (Aug 29, 2010)

Hoppy said:


> I just got a month's reprieve on when the light is needed, so I may go back to trying to get the ammeters to work for me, too. Putting them on the negative side may be important - the instructions show it wired that way. For the next week, though, I will be away - in Georgia, in fact.


I'm no engineer but I can't see how it would know whether it was on the negative side or not. Current into meter, current out..... the current should be the same on all points in the array..... your thoughts?


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## Rockhoe14er (Jan 19, 2011)

redfishsc said:


> I'm no engineer but I can't see how it would know whether it was on the negative side or not. Current into meter, current out..... the current should be the same on all points in the array..... your thoughts?


I agree. That's why i think that hoppy had a bad ammeter.


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## redfishsc (Aug 29, 2010)

He has two bad ammeters, which could be a batch problem. 

I'm hooking mine up today so we'll see. I've tested them all before and they worked fine but they've been sitting for a few months until I got my grad semester done and the stands built. Soon.....very soon............


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## Rockhoe14er (Jan 19, 2011)

i have the exact same model as hoppy too.


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## Hoppy (Dec 24, 2005)

I'm back, but too tired to work on this today. I agree that it shouldn't matter which side of the load the ammeter is on, but until I try it I won't be sure. I also think it shouldn't matter where the 10 VDC to drive the ammeter comes from, but it is possible it can't be in parallel with other uses of that voltage. (It has also occurred to me that the ammeters need about 50 mA each to drive them, and the little 10 VDC adapter I have may not produce enough current to drive two of them in parallel. As I recall, there is no current rating on the 10 volt adapter.)

EDIT: I read a bit more, and see that adapter is rated for 500 mA, so it should have no problem driving two ammeters in parallel.


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## redfishsc (Aug 29, 2010)

FWIW, I am powering my ammeters on the dimming voltage. I just have them wired in parallel (as you did too), NOT in line with the dimming pots. Been working fine for about a week now.


I have 3 circuits, 3 drivers, 3 pots, 3 ammeters, but only 2 9v power sources and 2 timers. 


First timer kicks on the dawn-dusk array--- 1 driver, and 1 9v power supply, and 1 ammeter. The 9v supply gives dimming voltage to the ammeter as well. All on at the same time, seems to work well. 

Second timer kicks on main lighting- 2 drivers, 2 ammeters, and the second 9v supply, which powers the dimming for the two ammeters and dimmer circuits. 


So far so good. I only dislike the super-thin 26 gauge wire they used in the ammeter.


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## Hoppy (Dec 24, 2005)

I checked the two ammeters today - both are now dead, no light when I use a 9 V battery to power them. I do have another ammeter, same part number, which I also tested with the 9 V battery and it lit up normally. So, now I'm thinking of using a single ammeter, with a 4PDT switch to let me read the current in each LED string independently, one at a time. Will this circuit work, or have I overlooked something?









Is there any value in connecting a small capacitor across the terminals of the ammeter to try to avoid voltage spikes on it? I can't see how it could be necessary, but perhaps it is.


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## jcgd (Feb 18, 2004)

I wouldn't switch it hot, but it looks fine to me.

One thing I don't understand is why you have connected the negative wires to each driver together. While it'll work all the same, if something goes wrong with the circuit it now involves both drivers instead of just one. I would personally have them isolated from each other if it's all the same. I assume you are connecting them so you only have to run one wire to the fixture?


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## Hoppy (Dec 24, 2005)

justincgdick said:


> I wouldn't switch it hot, but it looks fine to me.
> 
> One thing I don't understand is why you have connected the negative wires to each driver together. While it'll work all the same, if something goes wrong with the circuit it now involves both drivers instead of just one. I would personally have them isolated from each other if it's all the same. I assume you are connecting them so you only have to run one wire to the fixture?


The reason for the two negative wires being connected is so I can use a 4 wire cable to the light instead of a 5-6 wire cable, which would get pretty stiff. I wasn't able to find those in a flexible form without using even smaller gauge wires. That's the same reason I didn't use shielded cable, using the shield as a ground wire.

I can't think of a failure mode that would damage the drivers. LEDs fail open or shorted, to the best of my knowledge, and both would be of little consequence to the drivers. Open would just shut down one driver's output, and shorted would just make one driver waste more voltage, or adjust it down appropriately.

What bothers me is that I don't know what damaged the two ammeters, nor what kept it from working at all the first time. It might have been a voltage surge, or a hidden short in the wiring, or reversed wires to the power side of the drivers. I will be royally ticked off if I ruin another ammeter.

Why would you not switch the ammeter with the circuit hot?


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## jcgd (Feb 18, 2004)

Your switch is a break then make type, so it would cut the power for a split second. I read on another thread that if you open the cct while the driver is powered you can fry your leds with a voltage spike from the capacitor or something like that. Ill try to find the post and link to it.


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## O2surplus (Jan 31, 2010)

Hoppy said:


> The reason for the two negative wires being connected is so I can use a 4 wire cable to the light instead of a 5-6 wire cable, which would get pretty stiff. I wasn't able to find those in a flexible form without using even smaller gauge wires. That's the same reason I didn't use shielded cable, using the shield as a ground wire.
> 
> I can't think of a failure mode that would damage the drivers. LEDs fail open or shorted, to the best of my knowledge, and both would be of little consequence to the drivers. Open would just shut down one driver's output, and shorted would just make one driver waste more voltage, or adjust it down appropriately.
> 
> ...


The only problem that I can see with the circuit is the chance that there will be short moment in time, as the switch is thrown, that both drivers "see" an open circuit. I know that the meanwell drivers will raise the line voltage in order to compensate for the drop in current level though the circuit as it opens. This may result in a voltage spike that may cause damage to the leds.
Hoppy- I think your idea about adding the cap is a sound one. Sure would be nice to have an oscilloscope to be able to see what really going on in the circuit during the switch over phase.


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## Hoppy (Dec 24, 2005)

I think Meanwell would advise us to add a capacitor across the output if that was a good idea. Suppose a LED has an intermittent short or open, surely a good LED driver would be able to handle that without frying the LEDs. Also, is there any added risk in using the capacitor? I can see the possibility of it causing a voltage spike instead of damping it - I know an inductor in series will do just that.

Suppose a 5PDT switch were used, with the extra "pole" used to cut off the AC power to the driver? That sounds like it could cause even more problems.


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## jcgd (Feb 18, 2004)

Can you make it a make before break senario? 

Here's the thread about the voltage spike. They also discuss how the manufacturers don't give you much information about what to do/ what not to do.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> Can you make it a make before break senario?
> 
> Here's the thread about the voltage spike. They also discuss how the manufacturers don't give you much information about what to do/ what not to do.


That was an interesting read. It appears that if you are using near the full voltage the Meanwell driver puts out, there would be little problem in breaking the circuit and remaking it - the voltage couldn't go up enough to cause a high current spike. My LEDs are rated at about 3 amps, and I will be running them at 1.3 amps, or probably as low as 700 mA, so there is plenty of room for a current spike. (I think).

When I plug in the power, the LEDs take about 2 seconds to come on. This makes me wonder if the driver has an internal current damper - capacitor across the output. But, that could be caused by the AC side being damped.

Any suggestions for a different switching circuit to avoid this problem?


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## Hoppy (Dec 24, 2005)

Here is what might be a better way to use a single ammeter - but it does risk the wrong button being pushed, at the wrong time.










The push to open switches would be at each end of the DPDT switch so you would know to push the one the DPDT handle points to, to get a current reading.


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## jcgd (Feb 18, 2004)

Hoppy said:


> That was an interesting read. It appears that if you are using near the full voltage the Meanwell driver puts out, there would be little problem in breaking the circuit and remaking it - the voltage couldn't go up enough to cause a high current spike. My LEDs are rated at about 3 amps, and I will be running them at 1.3 amps, or probably as low as 700 mA, so there is plenty of room for a current spike. (I think).
> 
> When I plug in the power, the LEDs take about 2 seconds to come on. This makes me wonder if the driver has an internal current damper - capacitor across the output. But, that could be caused by the AC side being damped.
> 
> Any suggestions for a different switching circuit to avoid this problem?


I wasn't entirely sure what to take from that thread as I'm sure a lot of it was opinion and not fact, but some of the info makes sense and seems like the spike would be probable. However, my brain hurts too much to think on it too hard right now, but I am not sure that the current would limited to 3000mA or under. With the way rectifiers, caps and inductors all work together, I wouldn't trust my logic to assume that I would be safe just because I have some play with the current. So I'm not going to back you on that thought at the moment.

Instead, I like your make before break option that you just posted but I don't like how you can still open the circuit by accident, without the ammeter inline. The only thing I can thing of is if the buttons were mechanically or electrically interlocked, but this would likely make the setup more expensive than just buying another meter. The best you could probably do at this point is just make it very clear what button matches what selection, assuming I understand the schematic. I take it you select the line you want to measure with a switch to parallel the ammeter with that string, and then have a push button to open the circuit and direct the current through the meter?

One more option for anyone else doing this, especially where you have the voltage much lower than the driver max and by opening the circuit and having it reconnect could fry your leds is to simply install a 1ohm resistor rated for around 3 watts in the led string. Place a voltmeter across the resistor and whatever voltage is dropped over it is your current. AKA .7 volts would be 700mA. R=E/I so I=E/R so I=.7v/1ohm = 700mA. Using this method the string is less likely to be interrupted for whatever reason. I'm not saying I think it's superior, but is possibly more fail safe.


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## audioaficionado (Apr 19, 2011)

Well it makes sense if you have the minimum LEDs in a string, the Meanwell will reduce its voltage to compensate and maintain the set current. If you open the circuit, it would run the voltage to maximum in an effort to maintain the current level. If that maximum voltage exceeded the maximum LED voltage total in series, I can see how they could blow when the open is closed. If you have close to the maximum voltage in the string already, then there shouldn't be an open circuit risk.


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## Hoppy (Dec 24, 2005)

This is how I will wire it up, using a couple of 1 microfarad, 250 volt capacitors to dampen any possible surge in current/voltage when the switch is moved. If I use higher capacitance I might get a surge from the capacitors when the circuit is broken, but these should be small enough to give some protection, but no added surge.


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## redfishsc (Aug 29, 2010)

Would multiple caps of the same (small) size give you better surge resistance? Or would they all discharge at once? 

Mine are still working fine, all 3.


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## Hoppy (Dec 24, 2005)

The problem with the capacitors is that they accumulate about 50 VDC when the circuit is on, but once you break the circuit, the capacitor dumps its energy, with no restriction on current, to the LEDs. Putting a resistor in series would fix that problem, but might also reduce the damping effect of the capacitor. Since I don't think there is a problem in the first place, I see the capacitors as just an overkill solution. If I'm wrong, all I lose is about $100 worth of LEDs, but this way I save about $5 in resistors - am I a great businessman or what?

EDIT: Ok, so I decided to put a pair of 50 ohm, 10 watt resistors in parallel, in series with each capacitor, to limit the current from the capacitors to 2 amps. That also limits their surge protection to about 2 amps too. Since this current will flow for a fraction of a second, the wattage needn't be that high, but I can get them at Radio Shack cheaply, so I will.


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## jcgd (Feb 18, 2004)

I think that is a wise decision.


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## shoggoth43 (Jan 15, 2009)

A couple of questions...

You used thermal paste between the LED and the C channel. Did you use any between the C channel and the heat sink? Do you think the screws provide enough force to reduce as much space as possible to provide the best thermal transfer? Would cutting holes in the C channel and mounting directly to the main heat sink have provided a better thermal path?

The LEDs are usually on an aluminum plate so soldering probably isn't really an option for mounting to the main heatsink. I did find that most of the time I could solder wires to the LED without much problem, but if I needed to desolder it was easier to unmount the LED from the heatsink. I haven't tried using a resistance soldering station to see about mounting to the heatsink, but I doubt the aluminum would make that possible. Even if it were polished well, I would expect thermal expansion differences between the plate and the heatsink to crack the solder joint and pop the LED off and cause it to hang by the wiring but it might be an option.

Have you thought of incorporating any sort of a "soft start" into the circuit at all? Something which would slowly ramp up the brightness of the LEDs over some length of time to whatever the chosen brightness setting is? Something that would allow you to simulate some sort of dawn over 15 to 30 minutes vs. just having the LEDs snap on to full brightness? I would think having the timer shut off the voltage for an instant night would be slightly less problematic in comparison.

I've got some LEDs and drivers from an older group buy so maybe it's time I get back to that project. 

-
S


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## Hoppy (Dec 24, 2005)

shoggoth43 said:


> A couple of questions...
> 
> You used thermal paste between the LED and the C channel. Did you use any between the C channel and the heat sink? Do you think the screws provide enough force to reduce as much space as possible to provide the best thermal transfer? Would cutting holes in the C channel and mounting directly to the main heat sink have provided a better thermal path?


I used thermal adhesive to attach the LED stars to the channels, and the channels have thermal grease between them and the heatsink. I wasn't concerned about overheating since I was pretty sure the LEDs would spend their life being powered at around 700 mA or less, which doesn't generate much heat.


> The LEDs are usually on an aluminum plate so soldering probably isn't really an option for mounting to the main heatsink. I did find that most of the time I could solder wires to the LED without much problem, but if I needed to desolder it was easier to unmount the LED from the heatsink. I haven't tried using a resistance soldering station to see about mounting to the heatsink, but I doubt the aluminum would make that possible. Even if it were polished well, I would expect thermal expansion differences between the plate and the heatsink to crack the solder joint and pop the LED off and cause it to hang by the wiring but it might be an option.


You can't solder the stars to anything - the back surface is non-conductive plastic of some kind. You couldn't solder the emitters to the heat sink either, since that would short out the connections on the back. I have no problem soldering or unsoldering on LEDs cemented to the heatsink, as long as I use a 40 watt iron (I think it is 40 watts) but it is difficult to unsolder with a 15 watt iron.


> Have you thought of incorporating any sort of a "soft start" into the circuit at all? Something which would slowly ramp up the brightness of the LEDs over some length of time to whatever the chosen brightness setting is? Something that would allow you to simulate some sort of dawn over 15 to 30 minutes vs. just having the LEDs snap on to full brightness? I would think having the timer shut off the voltage for an instant night would be slightly less problematic in comparison.
> 
> I've got some LEDs and drivers from an older group buy so maybe it's time I get back to that project.
> 
> ...


I'm building this for someone else, and a programmed start/stop wasn't one of the requirements. I wouldn't have attempted it if it had to be programmable. I still have enough problems with simple LED circuits, without adding the complexity of programmability. It appears that the problem with sudden starts is only when you break or make the circuit to the LEDs, not when you turn the drivers on or off. This light doesn't yet start or stop suddenly anyway - it reacts a second or two after the power is turned on or off, for reasons I don't know. I also don't know if that behavior will change with the surge damping capacitors installed.


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## cggorman (May 9, 2009)

I know it's apples to oranges, but the LedEngin LZC (40w 12 die emitter) is rated at 1000mA continuous @ 150°C but has a pulsed max of 1500mA.

Cree doesn't seem to publish this data and the LedEngins are one of the most robust packages on the market, but I would think with a 3 amp continuous rating they could take a 4 amp surge no problem....maybe 5...

I'm pushing both my drivers and my emitters right up to their max ratings and have done many rapid on-off cycles of the driver (sometimes cutting AC and sometimes cutting dimmer circuit power) and never had any damage result...even to the relatively delicate Luxeon Rebels...(which I HAVE burned out during color testing)


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## Hoppy (Dec 24, 2005)

I'm sure interrupting the AC power to a LED/driver circuit is no problem, but what about interrupting the DC power from the driver to the LEDs? That is what will happen when I flip my 4PDT switch. As I see it, since the circuit will be at near the maximum output voltage of the driver, that voltage can't go up much when I open the circuit, so there shouldn't be much of a surge in current when the circuit is reconnected.  What there is should be largely absorbed by the capacitor.


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## redfishsc (Aug 29, 2010)

Don't interrupt the DC output. If you do, the driver will detect maximum resistance and spool up to 48v. When the power is reconnected, the LEDs will get hit with 48v regardless of how many LED's you have.

You say that you are already near the max voltage load, so you might get away with it, but I wouldn't risk it.


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## cggorman (May 9, 2009)

Oh, I missed that detail. Everything I've read says to avoid that at all costs...not sure why, but redfish sounds like he knows his stuff...


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## Hoppy (Dec 24, 2005)

One problem I seem to have is that the moonlight LEDs will be too bright. So, this circuit should allow dimming them easily. Will this work?










EDIT: Changed circuit - potentiometer doesn't have enough wattage capability to be used this way, so individual resistors to be used with a switch.

EDIT: Small error: the two resistors in series in the dimming circuit, should be in parallel. With the switch in one position there are 3 resistors in parallel, and in the other position, only one resistor.


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## Hoppy (Dec 24, 2005)

Rough day today! The good news: I installed a 2 position switch that allows cutting back on the moonlight intensity. That works well - it is the circuit above.

The rest is bad news: I rewired the control box to use the one operating ammeter I have, with a 4PDT switch to select which group of LEDs is being measured for current. The power to the ammeter circuit worked fine. The rest of the circuit checked out correctly with an ohmmeter. But, shortly after plugging it in, one of the capacitors "exploded". So, I removed them, and tried again. This time one row of LEDs worked fine, but not the other, and the ammeter wouldn't register any current. Then the second row of LEDs flashed weakly, so I unplugged the power. On opening the box I could smell overheated electrical stuff, with the smell seeming to come from the ammeter. I give up with the ammeter! For good!

Tomorrow I will get another project box so I can do it over with no ammeter. My plan is to use the PAR meter, while adjusting the LED driver current, to get the range of PAR I need. This will make getting usable data for figuring out how to design a light for a given PAR very iffy, but at least the light should work well enough for what it is intended to do. And, the dimmer knobs can be calibrated for dialing in the PAR desired.

Bummer.

But, I did get a notice from LEDgroupbuy that my optics have been shipped, so that's good news too.


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## jcgd (Feb 18, 2004)

Well that sucks. Is everything else still working properly?


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## audioaficionado (Apr 19, 2011)

Sounds like they used a bad shunt resistor not rated at high enough wattage capacity for the rated current. Puff there goes the magic blue smoke.


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## Hoppy (Dec 24, 2005)

The one step I didn't take, and should have, is to test the ammeter with a resistor and DC voltage to be sure it would indicate 0 -2 amps as advertised. It would have saved me some time, possibly. But, now is the time to look forward again. The lesson I'm learning is not to make another LED light, unless it is a very simple one.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> One more option for anyone else doing this, especially where you have the voltage much lower than the driver max and by opening the circuit and having it reconnect could fry your leds is to simply install a 1ohm resistor rated for around 3 watts in the led string. Place a voltmeter across the resistor and whatever voltage is dropped over it is your current. AKA .7 volts would be 700mA. R=E/I so I=E/R so I=.7v/1ohm = 700mA. Using this method the string is less likely to be interrupted for whatever reason. I'm not saying I think it's superior, but is possibly more fail safe.


Very early this morning I woke up thinking about this - cut my sleep 2 hours short. This solves my problem neatly. I think I will put these resistors in each LED string, with small holes through the control box case for voltmeter probes to contact each side of the resistors for a voltage measurement. This will let me measure the current as accurately as I need to, and will be as benign as possible, as far as their effect on the LEDs is concerned. 

Sometimes good ideas take awhile to sink in.


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## jcgd (Feb 18, 2004)

Hoppy said:


> Very early this morning I woke up thinking about this - cut my sleep 2 hours short. This solves my problem neatly. I think I will put these resistors in each LED string, with small holes through the control box case for voltmeter probes to contact each side of the resistors for a voltage measurement. This will let me measure the current as accurately as I need to, and will be as benign as possible, as far as their effect on the LEDs is concerned.
> 
> Sometimes good ideas take awhile to sink in.


Well... sorry to disrupt your sleep. But it is a good idea! I was on the fence on whether or not to add resistors to my setup. I almost went with the ammeters but then I realized I would need 6 or 8 of them so I scraped that. I think I'll add resistors.

It's also important to check the voltage drop and currents of the strings a few times a year to make sure there is no drift. It's much more important with parallel strings but it's good to make sure everything is in order and you don't want to overcurrent your LEDs and burn them out early.

Not so much directed at you Hoppy, but everyone following along.


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## Hoppy (Dec 24, 2005)

So many changes made to my original control box that now I'm afraid of solder lumps shorting out wires if I make still another change. So, I got a new project box and started the whole thing over. I have most of the components switched over to the new box now, and should get it wired up tomorrow. When I work by trial and error, I seem to emphasize *ERROR*!:redface:


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## jcgd (Feb 18, 2004)

Hoppy said:


> So many changes made to my original control box that now I'm afraid of solder lumps shorting out wires if I make still another change. So, I got a new project box and started the whole thing over. I have most of the components switched over to the new box now, and should get it wired up tomorrow. When I work by trial and error, I seem to emphasize *ERROR*!:redface:


Hey, hey. You make all the mistakes so we know what not to do. Works out awesome for me.:tongue:


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## S&KGray (Nov 12, 2008)

Adding resistors sounds like a good idea either way, as the primary way to measure the current, or a backup to double-check the ammeters are working properly.


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## jcgd (Feb 18, 2004)

S&KGray said:


> Adding resistors sounds like a good idea either way, as the primary way to measure the current, or a backup to double-check the ammeters are working properly.


Exactly. Two birds, and a very cheap stone.


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## Hoppy (Dec 24, 2005)

I found some 10 watt wire wound 5% 1 ohm resistors - 2 for about $1.50. Perfect for this use. I'm mounting them on terminal strips, so I can poke the voltmeter probes through holes to the mounting terminals. Such a simple solution it's embarrassing.

One thing I keep forgetting is that for electronic components, the rated voltage/wattage is that which just barely makes the component fail. In most other engineering fields, rated loads/strengths, etc. are set with a 15% or more safety factor built in, and often a 100% safety factor. The exploding capacitor I had was a 50 volt rated one, with 50 volts applied to it, so it failed with a boom! That's why I picked 10 watt resistors instead of 5 watt, which should have been entirely adequate.


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## jcgd (Feb 18, 2004)

Hoppy said:


> I found some 10 watt wire wound 5% 1 ohm resistors - 2 for about $1.50. Perfect for this use. I'm mounting them on terminal strips, so I can poke the voltmeter probes through holes to the mounting terminals. Such a simple solution it's embarrassing.
> 
> One thing I keep forgetting is that for electronic components, the rated voltage/wattage is that which just barely makes the component fail. In most other engineering fields, rated loads/strengths, etc. are set with a 15% or more safety factor built in, and often a 100% safety factor. The exploding capacitor I had was a 50 volt rated one, with 50 volts applied to it, so it failed with a boom! That's why I picked 10 watt resistors instead of 5 watt, which should have been entirely adequate.


Since you are putting them in an inclosed box you want them to run as cool as possible and having them oversized should keep them cool/warm to the touch - and they should outlive the fixture. I've read about some people using only 3 watt resistors and they will burn you if you touch them.


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## cggorman (May 9, 2009)

Yeah...we use a 5:1 safety factor in my industry.


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## Hoppy (Dec 24, 2005)

I have egg on my face! I finished assembling the control box again, and plugged it in. The light works fine. So, I used a voltmeter across the 1 ohm resistors to check the current. Guess what? I had over 2.5 amps flowing through the LEDs, and that is what killed my ammeters so thoroughly. Who would ever believe that a LED driver sold as a 1300 mA max adjustable current device would ever produce over 2500 mA direct from the dealer?

I did read often that it is good practice to start by removing the cover on the drivers, turning down the current adjusting pot to zero and then adjusting it to the 1300 max current. But, any rational person would think that the driver might be mis adjusted and produce 1400 mA, but over 2500 mA? I'm surprised I didn't cook them.

Once I get my temper back in control I will adjust them correctly then measure the PAR again. Now I wonder if the driver voltage is set to some absurdly high value too, like 100 volts DC. I will have to check that too. I don't expect to ever purchase another Meanwell product.


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## Rockhoe14er (Jan 19, 2011)

wow. My meanwell driver was set at 1400 ma max. That's pretty crazy that it was that high.


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## audioaficionado (Apr 19, 2011)

If they produce 2500ma @60v without burning up themselves, I'll definitely buy a couple.

Most of the DIY articles I've seen say to always dial down the current before any LEDs are powered up for the first time. Since you had the XM-L, you were golden anyway. Better your meters than a whole bank of CREEs.


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## jcgd (Feb 18, 2004)

That is insane. I've also heard they can be around 1400mA from the factory but 2500mA is ridiculous. After all I've heard about about meanwells I don't think I'll ever use their drivers. I am however using some of their power supplies for my build so hopefully they hold up. I believe its Tomas Research or something that has good drivers. I'll have to double check.


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## Hoppy (Dec 24, 2005)

audioaficionado said:


> If they produce 2500ma @60v without burning up themselves, I'll definitely buy a couple.
> 
> Most of the DIY articles I've seen say to always dial down the current before any LEDs are powered up for the first time. Since you had the XM-L, you were golden anyway. Better your meters than a whole bank of CREEs.


And, obviously, if you use Meanwell drivers you do need to take that first step. Now that I realize how easy it is to measure the current, with a 1 ohm resistor in series, I would do that for sure. Unfortunately, I learn by making mistakes.


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## jcgd (Feb 18, 2004)

So the par readings you gave us, they were with the drivers at 2500mA? Were the two drivers matched? That seems unlikely.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> So the par readings you gave us, they were with the drivers at 2500mA? Were the two drivers matched? That seems unlikely.


At this point I don't know what the current was when I took that data. I need to start over. I agree that it seems unlikely. I didn't leave it on long enough at that 2500+mA current to compare the two.

Here is the wiring diagram I ended up using:










Who knows what tomorrow will bring, when I start adjusting the drivers?


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## audioaficionado (Apr 19, 2011)

Hoppy said:


> And, obviously, if you use Meanwell drivers you do need to take that first step. Now that I realize how easy it is to measure the current, with a 1 ohm resistor in series, I would do that for sure. *Unfortunately, I learn by making mistakes.*


I've gotten most of my education at *'The School of Hard Knocks' *too.


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## jcgd (Feb 18, 2004)

I normally do alright, but I do have a nice collection of fuses that have saved me in the past.


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## redfishsc (Aug 29, 2010)

geeeez! I've had mine up to around 1500mA but 2500mA is insanity!


In future LED builds you might consider using the Thomas Research (AKA Inventronics) drivers, which come with their own built in 0-10v reference dimmer signal (you still need a 10K pot). They sell them at www.nanotuners.com and www.nano-box-reef.com


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## jcgd (Feb 18, 2004)

I've also noticed that LED group buy has started stocking a few of the inventronics drivers as well.


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## Hoppy (Dec 24, 2005)

Today I tried checking my multimeter with a couple of batteries to "calibrate" it. It was erratic, and it is an old one, so I went to Sears and got a new digital multimeter. Then I took off the covers of the drivers, adjusted the internal pots to the minimum, set the dimmers to a maximum, and readjusted the pots to get about 700 -750 mAmps maximum current. I was surprised at how little mvement of the pots makes a big difference in current. It was almost impossible to set an exact current for that reason - a very small jolt could change the setting, perhaps. 

Then I did some PAR measurements and plotted them as follows:
















I'm pretty confident that this data is good. At least I covered all of the bases I'm aware of. The best news is that now I can adjust the current down as low as I need to with the dimmer knobs.

When I finally get the optics I will do the final testing.

And, a photo of my well-equipped optics lab:


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## vim (Jun 29, 2011)

Hoppy, fantastic info! 

Thanks for going to all the trouble.

I'm suffering overload from trying to assimilate all the LED information available here and work out what to put over a new tank. It'll be a lot easier once you've refined the equation; are you expecting the optics to arrive soon? :icon_mrgr

Is that supposed to be PAR per square cm rather than m, or am I more confused than I think?!


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## redfishsc (Aug 29, 2010)

Hoppy, you can find multi-turn 10K pots if you need something that's more precise and slower in action. I nearly got some myself but they're 2-3X the price.


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## Rockhoe14er (Jan 19, 2011)

I really like how linear the realationship is between current and par. That is what i found when measuring my led's too.


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## Hoppy (Dec 24, 2005)

redfishsc said:


> Hoppy, you can find multi-turn 10K pots if you need something that's more precise and slower in action. I nearly got some myself but they're 2-3X the price.


The pots I referred to are the trimmer pots in the drivers, not the dimmer pots. My dimmer pots work fine, easy to adjust.

Vim, PAR is a standard measurement defined as micromols per square meter per second - it is a measure of the photons in that spectral range passing through an area of one meter squared per second. The equation I'm trying to develop can be in any units that are convenient - just the constant varies with the units chosen. (I'm having trouble figuring out that equation right now, but haven't given up.)


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## sajata (Aug 21, 2009)

redfishsc said:


> Hoppy, you can find multi-turn 10K pots if you need something that's more precise and slower in action. I nearly got some myself but they're 2-3X the price.


Mouser.com is a great place to get parts like that no min order and they will ship usps.

Sent from my DROIDX


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## vim (Jun 29, 2011)

Hoppy said:


> (I'm having trouble figuring out that equation right now, but haven't given up.)


YES!;please don't! This has to be the most exiting possibility since I learned you could feed plants Co2. 

I'd settle for being able to work out 'how many XM-L do I need over my tank', but if you get it figured out it should be possible to calculate for a configuration that provides both enough PAR and that nice shimmer effect not possible with CF.



Hoppy said:


> PAR is a standard measurement defined as micromols per square meter per second


I'm partly confused because the 'par-vs-distance' sticky shows PAR in square cm and, not having any first hand experience to calibrate my understanding, it's difficult to know if I'm reading the graphs right :redface:

enough from me. ON WITH THE SCIENCE! roud:


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## Hoppy (Dec 24, 2005)

Here is an equation that matches very well the data I have on this light, plus a couple of other LED lights I have, and reasonably well the data from a couple of other lights described in this forum:









Just remember that it is still tentative, until I get the 40 degree optics for the light and get more data with them installed.

One other thing: the equation is for lights consisting of just one row of LEDs. If there are multiple rows, the term "a^2" becomes "a x the distance between rows", but only if the distance between rows is greater than the spacing of the LEDs in a row.


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## jcgd (Feb 18, 2004)

I'm trying to use the equation but I'm getting high numbers. Can you double check it for me?

6 leds
1.7" between leds
48" from leds to substrate
40 degree optics
640lm per led (2000mA current)

I'm getting 2967.8umols for an answer. Can you just confirm this number? It seems stupidly high.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> I'm trying to use the equation but I'm getting high numbers. Can you double check it for me?
> 
> 6 leds
> 1.7" between leds
> ...


Sorry: I added an extra term "N", which shouldn't be there. I corrected the equation, and now it gives 500 mms of PAR.


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## jcgd (Feb 18, 2004)

Thanks Hoppy. That is still more than sufficient for my needs, haha. Maybe I should grow coral instead!


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## Hoppy (Dec 24, 2005)

justincgdick said:


> Thanks Hoppy. That is still more than sufficient for my needs, haha. Maybe I should grow coral instead!


If you are using a dimmable driver, you can easily reduce that as much as you want, first by adjusting the driver trimmer, then by using the dimmer circuit.


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## jcgd (Feb 18, 2004)

Yep, I've got both covered. I was concerned that I might not have enough light, but I think even if the equation way overshoots I'll still be fine. 

Why do they call them 3watt LEDs when they can put out anywhere from a fraction of a watt to 10watts? The xml anyways...


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## Hoppy (Dec 24, 2005)

Does anyone know of a reef LED light thread on any forum, with enough data to be able to see if the equation matches the measured PAR? I haven't found one.


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## jcgd (Feb 18, 2004)

The best I know of is reef central. There are a bunch of threads that have par levels from individuals. One thread in particular: http://www.reefcentral.com/forums/showthread.php?t=1678127


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## Hoppy (Dec 24, 2005)

If you rearrange the equation above to use it to determine what LEDs to use and what spacing to use, you get:









If I had this when I designed this light, which I wanted to hit 100 micromols of PAR at 700 mAmps current, Cree XP-G LEDs, I would have come up with a spacing of 2.25 inches, in a single row of "Outdoor White". I was going to have the light 48 inches above the substrate, with 40 degree optics. I would have used a 32 inch long light, as I am now, so that would be about 14 LEDs. Or, I would have used two closely spaced rows of two white colors, each with about 12 LEDs, which is what I had come up with by other means. I only switched to XM-L LEDs when the XP-G's were out of stock.


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## Hoppy (Dec 24, 2005)

justincgdick said:


> The best I know of is reef central. There are a bunch of threads that have par levels from individuals. One thread in particular: http://www.reefcentral.com/forums/showthread.php?t=1678127


That thread is so long, and contains so much chatter about other lights, that I couldn't find any real data there.


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## jcgd (Feb 18, 2004)

It's a big thread. Unfortunately many people don't accurately test for results. They usually just put the par meter over a coral and record it without distances or anything. I'll do some digging because I recently saw a few threads with well documented readings. I just don't remember where I saw them.


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## dafil (Jul 17, 2010)

Hoppy,I hope this will help http://www.reefcentral.com/forums/showthread.php?t=1826521&page=3
PAR data at page 3,6,10

and this http://joro.geodar.com/diary/40b/lang/en/


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## Hoppy (Dec 24, 2005)

dafil said:


> Hoppy,I hope this will help http://www.reefcentral.com/forums/showthread.php?t=1826521&page=3
> PAR data at page 3,6,10
> 
> and this http://joro.geodar.com/diary/40b/lang/en/


That is helpful! It is still not very specific, or if it is, it takes lots of reading on many pages to find all of the specifics, like what current is being used, exactly what LEDs, etc. As best I could figure it out though, the equation gives results that are not too far off of the measured results. (But, I had to make some guesses to do that.)


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## redfishsc (Aug 29, 2010)

Hoppy said:


>



Hoppy, if your "160" number in this image is based on the 160 lumens/watt of the XML, the final answer will be inaccurate for any drive current over 700mA, and proportionately bigger as the current approaches 3,000mA. 


If I'm not mistaken, the efficacy drops to about 100 lm/wt at 3,000mA.

I may be totally mistaken about what the "160" represents in your equation though


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## redfishsc (Aug 29, 2010)

I have a little data here that I just took, but there are so many LEDs in my array that the only one that might be of any use for you is the blue string (all the same LED with 60 degree optics).

http://www.plantedtank.net/forums/t...mless-cube-11g-rimless-glass-post1436796.html


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## Hoppy (Dec 24, 2005)

redfishsc said:


> Hoppy, if your "160" number in this image is based on the 160 lumens/watt of the XML, the final answer will be inaccurate for any drive current over 700mA, and proportionately bigger as the current approaches 3,000mA.
> 
> 
> If I'm not mistaken, the efficacy drops to about 100 lm/wt at 3,000mA.
> ...


The 160 is just a constant that makes the equation fit the data. It has no other significance. The "L" in the equation is the lumen output of one of the LEDs in the array, at the current being used. That comes from the charts in the Cree data sheets, or, for other LEDs, whatever the equivalent is.



redfishsc said:


> I have a little data here that I just took, but there are so many LEDs in my array that the only one that might be of any use for you is the blue string (all the same LED with 60 degree optics).
> 
> http://www.plantedtank.net/forums/t...mless-cube-11g-rimless-glass-post1436796.html


I need the distance between LEDs in each row, and how many rows, how far apart, in order to calculate what PAR you should have.


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## jcgd (Feb 18, 2004)

I believe the 160 is just a constant and you need to put in the lumens the led will put out at your given current. You need to know how many lumens the led puts out in order to use the equation.


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## nhung (Oct 6, 2009)

I made an excel spreadsheet that calculate the PAR using Hoppy equation. Since I could not attach an excel spreadsheet, the spreadsheet is inside the zip file.


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## Hoppy (Dec 24, 2005)

nhung said:


> I made an excel spreadsheet that calculate the PAR using Hoppy equation. Since I could not attach an excel spreadsheet, the spreadsheet is inside the zip file.


The spreadsheet works, if you copy the calculation formula to the right. I use a similar one, with more lines of data, so I can see all of the parameters involved. But, the equation is better as is if you want to use it to determine what configuration gives the PAR you want.

*Please don't forget: This is a tentative equation, until I can get my optics and repeat the tests with them.*


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## redfishsc (Aug 29, 2010)

You will notice some light attenuation from the optics, there is some restrike going on inside the optic for sure, as well as the lens itself attenuating the light some.


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## Hoppy (Dec 24, 2005)

Actually I'm beginning to wonder if I will notice anything at all - still no lens from ledgroupbuy! They are processing a replacement order, but I will believe I will get them if and when I do.


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## ElectricBlue (Jun 29, 2011)

There is some amazing and outstanding information in this thread. 


Great work everyone!


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## Hoppy (Dec 24, 2005)

Hip hip, hurray! The LED optics arrived today, right quantity, right parts, only 2 months after they were ordered. Tomorrow I plan to attach them, using a couple of tiny dabs of silicone. Then by Monday I should have the data on the finished light fixture.

Any tips on attaching these to the LEDs?


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## audioaficionado (Apr 19, 2011)

> Tomorrow I plan to attach them, using a couple of tiny dabs of silicone.


Sounds good to me. Holds well even when hot (unlike hot glue) and easy to remove (unlike epoxy).


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## Hoppy (Dec 24, 2005)

Optics all glued in place. There must be a better way to design the attachment of these.


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## redfishsc (Aug 29, 2010)

Hoppy said:


> Optics all glued in place. There must be a better way to design the attachment of these.



You absolutely got that right. Optic attachment is, IMO, the achilles heel of LED arrays. I'm convinced that the way that I have my lenses attached is causing considerable loss of efficiency. They are still way more efficient than fluorescents though.


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## audioaficionado (Apr 19, 2011)

What did you end up using Hoppy?


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## Hoppy (Dec 24, 2005)

audioaficionado said:


> What did you end up using Hoppy?


I used a tube of silicone sealant, GE Premium Waterproof Silicone, which I bought to use to hold wires in place on the heatsink. It works fine, but the whole method is just clunky, more like something consistent with candle technology instead of LED technology.

Here are the results of final testing of the light:










I tried the data in my equation and the equation gives about double the PAR that I got. I don't know if this is a flaw in the equation or due to light losses with the optics. In any case the equation is not usable in that form. I will be working on it to try to make it fit all of the data I now have.

The light does everything it is intended to do though. At 48 or 54 inches from the light, the PAR can be adjusted easily between about 10 and 35-40 micromols of PAR for each row of LEDs (one of Neutral White and one of Cool White). With both rows lit up, this gives from about 20 to about 75 micromols of PAR at the substrate of the tank it is intended for. And, allowing for the effect of the water, in focusing the light, and reflecting light off the glass, it gives good uniform PAR at the substrate too. If the drivers were adjusted to deliver a full 1300 mAmps of current, instead of 700 mAmps, it would give even more maximum light, way beyond what is needed for a high light planted tank. As is, it is a good high light, medium light or low light source for that tank.


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## Hoppy (Dec 24, 2005)

This is the list of parts and costs for the light, a little higher than it should be, because of the mistakes and need to rebuild the control box twice. But, still not a bad cost for what it is. If I had been able to get XP-G LEDs, and had made fewer mistakes the cost would be even better. It isn't really necessary to use 3 amp capable LEDs, although they do add the abilty to jack up the light intensity a lot, and using the LEDs at a fraction of their maximum power should make them last forever.


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## cggorman (May 9, 2009)

audioaficionado said:


> Sounds good to me. Holds well even when hot (unlike hot glue) and easy to remove (unlike epoxy).


Even low-temp hobby-grade hot glue melt around 120 C (250 F). If the stars and heatsink are getting that hot, there is a major design flaw.


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## cggorman (May 9, 2009)

Hoppy, what lens are you using? I've been pretty happy with each of the three different L'edil lenses I've used. They all drop right on and provide nice even light across the beam.


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## Hoppy (Dec 24, 2005)

I'm using 40 degree optics from ledgroupbuy, which look just like the illustration on their website. Their performance is acceptable, but the method of attaching just seems too crude, and I suspect they lose a lot of light in transmission through them. I would never have gotten the PAR I wanted without using them.

I suppose the best way to look at them is to consider how cheap they are, given what they do. And, they aren't simple lenses either, not compound lenses, but the profile is more complex than I expected.


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## Robbie1990 (Jun 16, 2011)

got another question for you hoppy,

I am going to be running 2 rows of xp-g led's on a freshwater setup

each row has 9 led's spread out over a 44" length. Led's will be ran at about 750mA so half power.

Will i be able to use some aluminium flat bar that i have lieng about for the heatsinks for each row or will i have to shell out for heatsinks?

led's are from ledgroupbuy so are 20mm base stars the flatbar is 6mm thick 40mm wide and as i say will be cut to 44" long with 9 leds on. i may also have some 50mm wide stuff


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## cggorman (May 9, 2009)

I can't find an optic with that star pattern from Carclo, Fraen, or L'edil. The overall shape of the lens looks similar to a L'edil Eva-W, but that one has a honeycomb pattern and the holders are all wrong.

Either way, even that bad lenses are still around 75% efficient. The good ones are in the mid 90s.


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## Hoppy (Dec 24, 2005)

Robbie1990 said:


> got another question for you hoppy,
> 
> I am going to be running 2 rows of xp-g led's on a freshwater setup
> 
> ...


I don't think I would try to use thin flat aluminum bars as heatsinks for that high a current, even though it is half power. In order for the heatsinks to get rid of the heat they need enough surface area to transfer the heat to the air. Finned heatsinks give lots of surface area for that purpose. Aluminum channel extrusions add the surface area of the "legs", and the wider the heatsink the more basic surface area they have.


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## Hoppy (Dec 24, 2005)

I am thinking that I am cheating a lot of people by working on my own to develop the "Grand Unified Theory" of PAR vs LEDs. I hate to be that stingy. So, here is the data I have taken from LED lights I have made:










Now, those of you who are grieving because you can't participate - please give it your best effort too. Right now I am stalemated on this. I can see lots of hints that a single equation can be developed to predict the PAR from any of these configurations, but it escapes me for now.


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## audioaficionado (Apr 19, 2011)

Do some Excel scatter plots and see if there are some linear correlations.


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## redfishsc (Aug 29, 2010)

audioaficionado said:


> Do some Excel scatter plots and see if there are some linear correlations.


Not a bad idea, and if I remember anything from calculus, if you can get a scatter plot with a linear pattern, you should be able to find some sort of equation that roughly matches it. Like the "reg eq" function on the old TI85 graphing calcs.


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## Hoppy (Dec 24, 2005)

Here is what I have come up with. In order to get everything to cluster around the line I had to assign a number for the cone angle for bare LEDs, which seems a bit small, but it isn't completely unreasonable.










I think this will work for a variety of LEDs and LED layouts. But, the rows of LEDs will need to be about the same distance apart as the LEDs in a row are. And, I suspect that at large distances from the light, maybe twice the length of the light, the correlation will break down completely. But, aquarium lights are very rarely that far from the substrate.

Anyone else have any luck with this?

EDIT: Added data from my Ebay 3 watt LEDs light, which still follow the curve pretty well. The cone angle of these LEDs I got from my own measurements, using the point where the PAR is down to half of the peak value to get the cone angle.


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## redfishsc (Aug 29, 2010)

Hoppy said:


> In order to get everything to cluster around the line I had to assign a number for the cone angle for bare LEDs, which seems a bit small, but it isn't completely unreasonable.


When you say "cone angle" for the bare LEDs, I'm not sure what you're referring to. 

At first I thought you were talking about the primary optic angle (the silicone dome over each LED), but when I saw that you had assigned them a 72 (XML) and 48 (XRE), I realized that you were either giving a half-angle, or a number that I'm just not familiar with. 

The XML has a 120 degree primary optic which should give you a 60 degree half angle.... if that is indeed what your numbers represent.


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## Hoppy (Dec 24, 2005)

The two angles I assigned were done that way to get the data to follow the equation. I could have worked out a different way, but I wasn't that sure the cone angle for the bare LED was determined the same way as with the optics. And, by then I was getting tired of trying to find another rational way to reconcile the data. Every other method I tried failed. The angle I'm looking for is the half angle of the cone, 30 degrees for a 60 degree cone, for example. Then, since most of the light is in the central half of that angle, I'm using 1/4 of the cone angle in the equation. That, when squared is proportional to the area of most intense light from the LED. The correlation doesn't work nearly as well using 1/2 or one times the cone angle. (The tangent goes negative with angles larger than 90 degrees.)

If you look at the Cree data in their pdf, the shape of the light intensity vs angle is considerably different for the XM-L and XR-E. And, I have no idea what the shape with the optics looks like, but I understand that it is best to work with only the inner half of the angle.

I may try to see what it takes to fit the data I have from Ebay cheap 3 watt LEDs to that equation, just to get a better feel for whether or not the equation will work with other LEDs.

One problem with trying to derive an equation from a bunch of data is the errors in the data. The PAR meter isn't accurate below 10, since it doesn't read in decimals, only whole numbers. And, my current measurements are probably riddled with errors since it was very hard to keep the multimeter probes in the right locations - probably a +/- 10% error at best. Then, when you square things the errors double. And, human errors in writing down data enter into it too.


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## redfishsc (Aug 29, 2010)

Now it does make sense. 

The Ebay LEDs will probably have a 140 degree cone angle compared to the 120 for the XML and the 90 for the XRE. 

Honestly the XREs, even though they are slightly older technology and slightly less efficient (not by a huge amount though) are actually more useful for us right out of the box since the primary optic is so tight. 


When you put a PAR meter up to an XRE and to an XPG at the same drive current, the XRE will give a surprisingly higher PAR reading because the optic is tighter.... even though the XPG is actually brighter. It's just scattered more. 


Since most of us won't need 60 degree optics (the widest optic commonly available for XP series), the included 90 of the XRE makes it a pretty good choice for tanks up to about 20" deep.


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## Hoppy (Dec 24, 2005)

I updated the graph, with my Ebay LED light data. For cone angle I used my data from a single LED, using the point where the PAR drops to half of the peak value. That gave me an 80 degree cone angle. The two points for that light fall pretty close to the same line.


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