# How to use TC-420 to control Ldd drivers



## jeffkrol

got my parts and had some time to play w/ them.
Seems everything is fairly easy to modify.
FUN thing is you can actually (in theory) run both constant voltage and constant current on each channel..

Simple wire addition to the "gate" of the MOSFET
I attached 4 and left one off.. didn't need it for "the plan"..
Figured why push my luck.
First used one power supply (9V) to feed both the unit and LED's.
Attached added wire to the LDD PWM wire.
Worked perfectly, 
Second tried 9v power to the unit and a secondary 24V power to the leds.
Only hooked 9 V to both +/- of the input.(basically just tc-420 power)
Took 24V and only added a ground (-) to the input connection in order to have a common ground.
also worked flawlessly..

anyone doing it though YMMV..

I do have some 24V strips that I could hook to the unit and run everything through the Input. don't see how it wouldn't work..

Anyways food for DIY thought..

It is only slightly cheaper than a Typhon though. You do get 1 more channel and a computer interface, and flexibility in LED driver type.. 

One last note : I didn't check all 4 yet but it shouldn't be an issue.. LDD PWM takes VERY little current..
Pieces of Cat5 wire is fine for the PWM gate circuit.. 











Strips and LDD running of the same channel:
https://youtu.be/1qm_5w7DDuA


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## pwu_1

One would do this mod to either get around the 4amp max per channel limitation or perhaps enable the use of LEDs with different voltage requirements right?

Can you draw some diagrams or take some pictures to show how the LDD driver is hooked up in relation to the TC420? I'm having a hard time picturing how it is hooked up based on your description.


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## jeffkrol

pwu_1 said:


> One would do this mod to either get around the 4amp max per channel limitation or perhaps enable the use of LEDs with different voltage requirements right?
> 
> Can you draw some diagrams or take some pictures to show how the LDD driver is hooked up in relation to the TC420? I'm having a hard time picturing how it is hooked up based on your description.


first one would do it to dim constant current PWM controlled drivers. So yes, in a sense, to exceed the "limitations" of 4A per channel BUT not to control things like large Beamsworks..

for that you could, theoretically, replace the on board Mosfets *the 5 little squares in a column on the right side.
THOSE are what limits the current capacity..
you may be also able to cascade them (add another set of MOSFETS like we did above (using the internal MOSFETS to control another MOSFET )but that gets "complicated" )

As to the LDD arrangement, I'll scribble something up later..
Basicaly though on an LDD you have 5 wires.. The dim wire will go to the added wire to the tc420..
The rest depends on your power needs for the LDD strings.. IF you can get away w/ one that is within the 12-24 range you can 1)power the TC-420 and 2 power the string BUT bypassing (not connecting) anything to the MOSFET outputs (5 screws listed ch1,2 ect..)
An internal voltage regulator is what feeds the logic circuits..Actually that is why the TC will actually be powered by less than 12V in reality..I suspect you could go close to 5 and still get it to function.. BUT driving constant voltage LEDs w/ 5 volts is pretty silly for outr uses.. like 2 diodes in series and x parallel. up to 4A (ignore this it is probably more confusion than needed.. )

The "plus" on there is just common to both input and output..
If your ps exceeds 24V you really shoud use 2 ps 1 for the tc one for the leds.. Only catch is to creat a "common ground" 2 the 2 power supplies.

fortunately, in my case, my 56V DC ps has both a 5V and 12V rail..
so all I had to do was jack it into the other input (left side has a barrel jack for power). The ps formed the common ground.
Though I did use a 9v PS (actually more like 11) to power the TC-420 and a 24v ps for a LDD "test strip"..and a common ground .. worked fine..

just pretend the tc420 is the Storm 
What they don't show its the power to the Storm (or TC in this case)
RED wires on the Strom coming from the PWM outs is the same as the added wires to the gate of the MOSFET (5v PWM signal)

as a side note the barrel plug size is the same as the one for the Typhon (same polarity as well so it was plug and play for me) from Steves, and prob same as the Storm X










considering the TC-420 is only marginally cheaper than a Typhon BUT w/ one more channel and a computer program interface, one would need to consider what they need..

I did it because I didn't want to build a box for the Typhon AND wanted to more easily reconfigure via USB..

build note.. Cat5 wires fit easily into the slot behind the screws BUT it is easier if you remove the screws first
Using the screw as a strain relief is also possible..


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## jeffkrol

The most complicated setup. The 12-24V ps needn't be very strong.. and isn't "really" limited to that range BUT it is convenient:











Specs for the MOSFET. To be honest, I'm not sure why they limit the current to 4A.. These can take a lot more than that..
www.qualiteitems.com/images/09N03.pdf


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## Immortal1

Looks like you have been busy with the TC420 
Your 12:44pm picture is quite interesting except I am envisioning 3 Kessel type lights, each with a single white, some red, some blue, some green and some cyan LEDS. Now I just have to machine an aluminum housing to mount the LED's in


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## pwu_1

hi Jeffkrol, I hope you are still monitoring this thread. Anyways, I need some help from you if possible.
I bought a new light off fleabay, thinking I would be able to control/dim it using the TC-420. The light came today and I was wrong about the light and it turns out it is using a mean well LPC-60-1050 constant current driver. The Mean Well LPC-60-1050 takes an AC input and outputs up to 48 volts and 1050 ma constant current. That means the driver as is won't work with the TC-420.
So, I did some searches online tonight and found this other driver Mean Well LDH-45B-1050. The LDH-45B-1050 is a DC-DC boost constant current driver with input voltage of 18 volts to 32 volts and outputs 45.15Watts of power.
Here is the spec sheet--> http://www.meanwell-bg.com/files/Models/LDH-45-spec.pdf
So, my question to you is, I should be able to use the TC-420 to control the LDH-45B-1050 by soldering a wire to the MOSFET on the TC-420 and then connecting that to the PWM pin(pin 5) of the LDH-45B-1050 right? I have 2 of these lights and I want to add some RGB strips for ramp up/down so here is my plan.
1) Get 24 Volt DC regulated power supply, something like the mean well NES-350-24 power supply to power everything.
2) Get 24 Volt RGB LED strip
3) TC-420
4) LDH-45B-1050 constant current driver(2x)
I would connect it as follows:
MeanWell NES-350-240 to power everything so connected to the TC-420 and each of the LDH-45B-1050

TC-420, Channel 1,2,3 will be connected to the RGB light strip for Red,Green,Blue channel.

Channel 4 and Channel 5 will be modified to add a wire from the gate of the MOSFET to the PWM pin of the LDH-45B-1050. Each channel would get one LDH-45B-1050 so that I can control each light separately. 

Do you see any issues with this plan? It should work right? Any advice you can give would be greatly appreciate it.


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## jeffkrol

pwu_1 said:


> hi Jeffkrol, I hope you are still monitoring this thread. Anyways, I need some help from you if possible.
> I bought a new light off fleabay, thinking I would be able to control/dim it using the TC-420. The light came today and I was wrong about the light and it turns out it is using a mean well LPC-60-1050 constant current driver. The Mean Well LPC-60-1050 takes an AC input and outputs up to 48 volts and 1050 ma constant current. That means the driver as is won't work with the TC-420.
> So, I did some searches online tonight and found this other driver Mean Well LDH-45B-1050. The LDH-45B-1050 is a DC-DC boost constant current driver with input voltage of 18 volts to 32 volts and outputs 45.15Watts of power.
> Here is the spec sheet--> http://www.meanwell-bg.com/files/Models/LDH-45-spec.pdf
> So, my question to you is, I should be able to use the TC-420 to control the LDH-45B-1050 by soldering a wire to the MOSFET on the TC-420 and then connecting that to the PWM pin(pin 5) of the LDH-45B-1050 right? I have 2 of these lights and I want to add some RGB strips for ramp up/down so here is my plan.
> 1) Get 24 Volt DC regulated power supply, something like the mean well NES-350-24 power supply to power everything.
> 2) Get 24 Volt RGB LED strip
> 3) TC-420
> 4) LDH-45B-1050 constant current driver(2x)
> I would connect it as follows:
> MeanWell NES-350-240 to power everything so connected to the TC-420 and each of the LDH-45B-1050
> 
> TC-420, Channel 1,2,3 will be connected to the RGB light strip for Red,Green,Blue channel.
> 
> Channel 4 and Channel 5 will be modified to add a wire from the gate of the MOSFET to the PWM pin of the LDH-45B-1050. Each channel would get one LDH-45B-1050 so that I can control each light separately.
> 
> Do you see any issues with this plan? It should work right? Any advice you can give would be greatly appreciate it.


24V ribbons or 12V makes little difference.

But if I understand this correctly it would only mean changing from a NES-350-240 to a NES 350-120.
The step up driver is unaffected by the change...

AFAICT it should work as you are designing. 

How many diodes and power for the constant current fixture you bought?
Off hand don't know of any LED commercial fixtures that use that Meanwell driver..


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## pwu_1

jeffkrol said:


> 24V ribbons or 12V makes little difference.
> 
> But if I understand this correctly it would only mean changing from a NES-350-240 to a NES 350-120.
> The step up driver is unaffected by the change...
> 
> AFAICT it should work as you are designing.
> 
> How many diodes and power for the constant current fixture you bought?
> Off hand don't know of any LED commercial fixtures that use that Meanwell driver..


Hi jeff,
Its a aquatic life 36 inch 1 watt led fixture. Made for Marine tanks.
Right now on ebay they are clearing them out for 39.99 + 7.99 shipping
It has 36 1 watt leds but since the fixture was made for marine tanks the leds are a mixture of blue/white/purple leds. I ripped out all the blue ones and ordered some 6500k leds from china. I figured even if I break the led strip I still have a very good and nice looking heatsink for doing DIY(much better construction than beamswork)
The current configuration is a bit complicated(to me anyways). there are 2 strips of lights, each strip has 18 leds broken down into sets of 6 leds in series and then 3 groups of the 6 leds in parallel. Then, the 2 strips are connected in series so I guess the math works as follows:
1050ma/3 = 350ma. So 350ma going into each of the 6 leds on each strip and then the 2 strips in series means it'll potentially draw up to 21 volts each(3.2 typical forward voltage X 6) strip, X2 so total voltage of around 40-42 volts.
Anyway, I thought about it some more and I already have a 15 volt adjustable power supply(adjustable 12.5 to 18 volts) and 12 volt rgb strips purhased for my failed beamswork DIY. So, I got the LDH-45A-1050 driver instead and I will drive the LDH with about 12.5-13 volts and the rgb strips will be slightly over driven.
But I'm really hoping this will work since I really like how the TC-420 enables me to control the light

I'll update and let you know if I can get this working


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## jeffkrol

you got my attention...



> purhased for my failed beamswork DIY.


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## pwu_1

jeffkrol said:


> you got my attention...


oh, when i say "failed" I mean it wasn't as bright as I had hoped it was going to be.
Everything works as I thought it should. So far the rgb strips and the beamswork Pent has been running fine on 14 volt input voltage.
The two big things are 1) I don't think it is bright enough for my needs. 2) The light gets very hot when I have the Pent and the 3 rows white 5630 running on full blast. It is winter now so it'll probably work for a while(only been running a few days since I'm just cycling the tank right now) but I can see things getting way too hot once the weather warms. I didn't like the idea of adding fans because having taken the end caps off the beamswork, I don't think heat dissipation is very good on the beamswork,
Then I found this aquatic life and read about changing LEDs and decided to try that instead.


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## jeffkrol

Ahhh thanks..
T


> he light gets very hot when I have the Pent and the 3 rows white 5630 running on full blast.



though technically somewhat expected w/ "overdriving" the strips.. it is good to have verification..

by chance, and I know it will be way less light than wanted, did you try firing the Beamswork w/ just 12V? Can't remember if you did.
If it even "lit" it should be fairly dull..


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## pwu_1

jeffkrol said:


> Ahhh thanks..
> T
> 
> 
> though technically somewhat expected w/ "overdriving" the strips.. it is good to have verification..
> 
> by chance, and I know it will be way less light than wanted, did you try firing the Beamswork w/ just 12V? Can't remember if you did.
> If it even "lit" it should be fairly dull..


The power supply I have only goes down to about 12.4 volts as measured using my voltmeter.
at 12.4 volts the beamswork still lights up but yes, much dimmer.


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## pwu_1

Hi Jeff I'm just looking at the Pin out for the Meanwell LDH driver and I have a question about how you hooked up the PWM wires.
So there is a + and - wire for PWM dimming. From the TC420, I would need to hook the common + to the PWM Dim + of the LDH driver(pin 5) and then the wire from the MOSFET to the Dim -of the LDH driver(Pin 3) right?'

Actually I just looked at your diagram, looks like I would hook it up like this instead
the + wire on the PWM dimming would be connected to the + of my 12Volt power supply
the - wire on the PWM dimming would be connected to the wire that I solder from the MOSFET. 

The common + of the TC420 output would not be used to drive the PWM dimming circuit. That sound about right?


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## jeffkrol

There is only one PWM wire..The white one is PWM DC "in" (5V positive or so)
2 DC (R,Bk) in 2 DC out (Y,Bl)

PWM white wire goes to the gate of the MOSFET..which is either 0 or 5v + depending on "state".

ignore the MOSFET for a moment.. it is just like this:


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## pwu_1

The LDH boost driver has 7 pins. 1 PWM + , 1 analog +, 1 PWM/Analog -

spec sheet here: http://www.meanwell-bg.com/files/Models/LDH-45-spec.pdf

The output from the MOSFET, is that + or -?


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## jeffkrol

pwu_1 said:


> The LDH boost driver has 7 pins. 1 PWM + , 1 analog +, 1 PWM/Analog -
> 
> spec sheet here: http://www.meanwell-bg.com/files/Models/LDH-45-spec.pdf
> 
> The output from the MOSFET, is that + or -?


Pin 5 (or blue wire) is the PWM 5V plus..connect to gate.
dim - (3 or black) is used for analog dimming (.25-1.3V).. unused for PWM..


black/Red (6,7) isolated on the other side are the "to the LED" side..
bl/r on the other side.. "to the supply"


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## pwu_1

I received the boost drivers today and spent the evening hooking it up. It works!  I have one fixture hooked up to channel 4 and the other one hooked up to channel 5. The only minor annoyance is that at less than 10% power, the light flickers. Between 10 and 30% or so,power, the drivers makes any annoying high pitched buzzing noise. It's not very loud so I can probably live with it but the noise is louder at lower input voltage. At 17-18volts the noise is almost completely gone. Now I'm wondering if the 24 volt input driver might work better.
All I need now are some wires coming from China and I'll be able to mount the rgb strips onto the fixture and do the ramp up using the rgb strips.


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## jeffkrol

(Things you miss but may bite you in the..a....)

One thing that is an unknown at this time is the PWM frequency of the tc-420..
The buzzing may be caused by a frequency mismatch (this is just a guess btw)
I didn't notice that the step up driver's PWM range is 1-10kH.
Most aduinos' out of the box use 500-ish Hz.. (1/2kH)


> The Arduino has a fixed PWM frequency of 490Hz - or does it? On digital pins 3, 9, 10 and 11 it's 490Hz, but on pins 5 and 6 it's 976Hz. Confused? And it is possible to change the PWM frequency to a higher (or lower) frequency by altering the timer prescalers


In a home built unit this is changeable in code..(scaler to 8)
https://arduino-info.wikispaces.com/Arduino-PWM-Frequency
There are other ways..
http://www.electronicecircuits.com/electronic-circuits/4046-ten-times-frequency-multiplier-circuit
or:


> There have been similar projects here that used a frequency-to-voltage converter followed by a voltage-to-frequency converter (two chips). You can keep 50% duty cycle that way.
> Here are typical V-to-F and F-to-V chips that you might want to look at: NJM4151, KA331, XP4151. They are virtually identical.


http://www.njr.com/semicon/PDF/NJM4151_E.pdf
DAC to ADC.. w/ a change in timing..
simpler but only gets you to 980Hz:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/3327


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## pwu_1

Yeah before the driver arrived I was looking at the pwm frequency and wondering if it would work. The weird thing is that the buzzing changes as the input voltage is changed. Originally I was thinking it was the driver having trouble keeping up with the low dimming level but now I'm wondering if it might be the tc420. I guess I can try and power the 2 using different power sources to see. For now though I'm not going to worry too much about it. The light fixture probably won't be run at less than 30% for long anyway, the rgb strips will be used for that


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## pwu_1

I did some more testing today. Tried using different power supply for tc420 and ldh driver. The tc420 had a 12 volt power supply while the mean well driver had adjustable power supply. Same buzzing noise was heard from the driver between 12.5 Volts and 15 volts. Once the input voltage went above 15 volts the buzzing noise became very faint, basically inaudible. So, now I'm wondering if the 24volt driver might work better. According to the specs supposed to be a bit more efficient too


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## masterross

Hi guys,

I have made my aquarium light by using 5050 led strips (total 200W).
Do you think it's a good idea just to replace MOSFETs with ones with more current or there is a better solution?

Regards,
Ross


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## jeffkrol

masterross said:


> Hi guys,
> 
> I have made my aquarium light by using 5050 led strips (total 200W).
> Do you think it's a good idea just to replace MOSFETs with ones with more current or there is a better solution?
> 
> Regards,
> Ross


TC-420 can handle 240W "natively" . 48W per channel.. so dividing it up so as to meet that restriction is the easiest thing to do....


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## masterross

Hi jeffkrol,

The problem is that I also use RGB stripes, so I have only 2 channels free.
And for my other project (700L aqua) will need more power.

Regards!


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## jeffkrol

masterross said:


> Hi jeffkrol,
> 
> The problem is that I also use RGB stripes, so I have only 2 channels free.
> And for my other project (700L aqua) will need more power.
> 
> Regards!


so you have 2 choices .. Either tap the 5V "gate" off the 2 MOSFETS
and use that to control the gate of another 2 high power MOSFETS.. or use the 12V "out" of the current channel to do the same thing..

Only really depends on which MOSFET you get..The drain and sink of the new MOSFETS would come directly from the power supply..

"control" is just the "out" on the controller.. PNP for 12V (neg control) NPN for directly off the 5v (pos control) gate tap..










NPN are more efficient...

Above my paygrade to design it completely but one recommendation comes from this.. This is opto isolating the high current MOSFET from your controller but beyond me a bit..
Uses the 5v "pin" off the tc-420 MOSFET to light an LED that drives the gate of the new power MOSFET










and as to the first diagram.. not even sure the transistor is needed but....


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## masterross

Hi jeffkrol,

You really helped me.
I was hoping directly to replace the original MOSFETs with more powerful but using external ones will handle more current.

Thanks a lot!

P.S.

Just saw that original dtu09n03 has Id = 55A but probably cant dissipate the heat?


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## jeffkrol

masterross said:


> Hi jeffkrol,
> 
> You really helped me.
> I was hoping directly to replace the original MOSFETs with more powerful but using external ones will handle more current.
> 
> Thanks a lot!
> 
> P.S.
> 
> Just saw that original dtu09n03 has Id = 55A but probably cant dissipate the heat?


Probably not.. and somewhere the specs were worked out..and the orig rating is close to max at that voltage..and yes no heat sinking of any kind for the internal MOSFETS..just surface mounted to the board..

Ther are 2 MOSFETS w/ the same nuber but different specs/company. 
Can't remember which one is the actual one, Din-tek or another one..

The rating is not exactly what you need to use.. 
See fig. 9
http://cdn.sparkfun.com/datasheets/Components/General/FQP30N06L.pdf

And use the DC" one to figure max. "full on continuous" parameter...


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## masterross

Thx mate,

You are right!
I've found the right datasheet:
http://www.din-tek.jp/Upload/Product Doc/Datasheet/DTU09N03.pdf

And according this info: 
http://www.nxp.com/documents/application_note/AN11158.pdf#G1000483671

the max DC current at 12V is *4.96A* at 25 degree!


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## masterross

Thx mate!

You are right.
I've fount the right datasheet:
http://www.din-tek.jp/Upload/Product Doc/Datasheet/DTU09N03.pdf

and according this equation info:
http://www.nxp.com/documents/application_note/AN11158.pdf#G1000483671

the max DC is *4.96A* at 15V ant 25 degree!


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## masterross

jeffkrol said:


> Probably not.. and somewhere the specs were worked out..and the orig rating is close to max at that voltage..and yes no heat sinking of any kind for the internal MOSFETS..just surface mounted to the board..
> 
> Ther are 2 MOSFETS w/ the same nuber but different specs/company.
> Can't remember which one is the actual one, Din-tek or another one..
> 
> The rating is not exactly what you need to use..
> See fig. 9
> http://cdn.sparkfun.com/datasheets/Components/General/FQP30N06L.pdf
> 
> And use the DC" one to figure max. "full on continuous" parameter...


Thx mate!

You are right.
I've fount the right datasheet:
http://www.din-tek.jp/Upload/Product Doc/Datasheet/DTU09N03.pdf

and according this equation info:
http://www.nxp.com/documents/application_note/AN11158.pdf#G1000483671

the max DC is *4.96A* at 15V ant 25 degree!


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## Penta

*Burned two LDD-305H*

Hi,
I did everything exactly by the diagram with my TC420 connecting a LDD-350H driver to a 36V power supply and 10 Cree XPE2. They start flashing , the driver got hot and there was a smoke.
OK, maybe PS was not good enough. I got another driver and powered it with better 12V PS. This time I've used only 3 XPE2 .It worked for like 2 min, the TC420 was dimming the LEDs and then i sense a smell. Turned of and then on measured the current. It started from 400mA and within few seconds jumped to 2A, getting very hot.
What I did was to power the TC420 by the optional barrel input, made common ground connecting V- of the PS to the V- of the TC420 upper screw connector and then to the V- of the LDD driver. 
V+ of the PS to V+ of the driver. PWM was connected to the gate of MOSFET.
I've checked my wiring a thousand times and it was OK. Maybe LDD-350H was supposed to work only on PCB board as there are some resistors on it ?
None of the build-in protections were triggered


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## jeffkrol

First guess is you reversed the plus sides on the LDD. Not likely, but the easiest way to pop one.


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## Penta

jeffkrol said:


> First guess is you reversed the plus sides on the LDD. Not likely, but the easiest way to pop one.


I wish it was that simple


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## jeffkrol

http://www.tc420.net/images/TC420/TC420-High-Power-LED-Circuit.png


Here is another drawing


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## Penta

jeffkrol said:


> http://www.tc420.net/images/TC420/TC420-High-Power-LED-Circuit.png
> 
> 
> Here is another drawing


The first screw is (-) and the second (+) , its reversed on this drawing.


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## jeffkrol

Sorry, was on the road so no way to check mine . You're right they are reversed..
Can you draw what you have?? 

This is a pretty easy set up. Hardest thing is wiring the internal Mosfet gate...
Check voltage on the PWM wire when output is set to 100%.. Should be around 5V or so.


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## Penta

The PWM was 4.8V at 100% without driver attached. I don't have working driver atm.
You are right the setup is very simple, there is nothing to go wrong but still ... I was looking at the PCB boards for these drivers, there are resistors mounted on them. Maybe this is the problem.


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## jeffkrol

Penta said:


> The PWM was 4.8V at 100% without driver attached. I don't have working driver atm.
> You are right the setup is very simple, there is nothing to go wrong but still ... I was looking at the PCB boards for these drivers, there are resistors mounted on them. Maybe this is the problem.


The resistors are "pull down" resistors to make sure the driver doesn't default to "on" if you lose your controller..
So if you hook a power supply to the LDD in and diodes to the out but your PWM is "open" it won't light..


Personally a PIA for troubleshooting. There are some boards w/ a jumper to put them in line or off line..


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## Penta

Everything is working perfectly now. 
The problem was the separate power supply that I've used to power TC420 (common ground with the PS for the LED's).
Now I use DC-DC converter 48 to 12V for the TC420.


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## jeffkrol

FYI Just found a cheap source of TC-420's..
TC420 Programmable Time LED DC 12V-24V Leynew Controller


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## ichristos

Hi jeffkrol, 
after burning one tc420 (accidentally plugged in 220v ac...) I got a 2nd one and then soldered wires on gates of mofset 1, 2, 3 (have 3 drivers)
what's the expected voltage between the gate and v(-)? 
I get a reading of 0.3v @ 100%, which is not enough to feed the pwm of the driver... Using an arduino pwm pin, set to ~3v works fine. Also changing the output for that pin will dim the leds fine. 

Admin of tc420.net was very helpful so far!

Thanks! 


Sent from my A0001 using Tapatalk


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## jeffkrol

ichristos said:


> Hi jeffkrol,
> after burning one tc420 (accidentally plugged in 220v ac...) I got a 2nd one and then soldered wires on gates of mofset 1, 2, 3 (have 3 drivers)
> what's the expected voltage between the gate and v(-)?
> I get a reading of 0.3v @ 100%, which is not enough to feed the pwm of the driver... Using an arduino pwm pin, set to ~3v works fine. Also changing the output for that pin will dim the leds fine.
> 
> Admin of tc420.net was very helpful so far!
> 
> Thanks!
> 
> 
> Sent from my A0001 using Tapatalk


Last one I measured was 3.6-ish volts.. 
and 450-ish Hz
hooked it to the LDD and worked.
But crude measurements..
Picture or diagram (sloppy is fine) would be helpful..


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## ichristos

Hi thanks!!! 
mofset ch1 max out at 0.37v
mofset ch2 max out at 0.37v
mofset ch3 max out at 4v
mofset ch4 max out at 4v
mofset ch5 max out at 4v

could it be that my lame soldering skills destroyed mofsets 1,2?!

tomorrow I will try soldering 4,5 and test again... 

thanks! 



Sent from my A0001 using Tapatalk


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## jeffkrol

ichristos said:


> Hi thanks!!!
> mofset ch1 max out at 0.37v
> mofset ch2 max out at 0.37v
> mofset ch3 max out at 4v
> mofset ch4 max out at 4v
> mofset ch5 max out at 4v
> 
> could it be that my lame soldering skills destroyed mofsets 1,2?!
> 
> tomorrow I will try soldering 4,5 and test again...
> 
> thanks!
> 
> 
> 
> Sent from my A0001 using Tapatalk


your not using the MOSFET exactly.. Just the circuit board contact to the gate..Technically (though not part. easily) they could be removed..

Likely leg lifted from pad on the board..
http://www.acvariu.ro/forum/posts/list/200/36620.page


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## Kampo

I'm looking to setup a budget reef on a 24x24 cube, I know this is not a reef forum but this thread pertains to it. Going to be using a Marsaqua Chinese black box for lighting. I know these can be moded for ramp timers, but it takes a 0-10V Analog input. can you use something like this on a TC420 to get ramp control to the light from the controller? if so would I just need to power the tc420 with a cheap 12V psu?

PWM to 0-10V Digital to Analog Module Green - Tmart


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## jeffkrol

Kampo said:


> I'm looking to setup a budget reef on a 24x24 cube, I know this is not a reef forum but this thread pertains to it. Going to be using a Marsaqua Chinese black box for lighting. I know these can be moded for ramp timers, but it takes a 0-10V Analog input. can you use something like this on a TC420 to get ramp control to the light from the controller? if so would I just need to power the tc420 with a cheap 12V psu?
> 
> PWM to 0-10V Digital to Analog Module Green - Tmart


Technically yes..but that one doesn't list PWM voltage range it takes nor the PWM frequency.
Also some Marsaqua's will do 10V PWM as well.
. No guarantee on what driver or topology they use..

IF it can do 10V PWM you only need to add a 10V PS to the TC-420 and attach to the outputs. No modding necessary or add on board..
The MOSFETS "pulse" the voltage you use on the supply side.
A lot of drivers are "dual use" on the Dim circuit..
I would probably try that first if you can find a cheap 10V switching power supply..If not there are plenty of cheap "voltage regulators" out there to drop your voltage from say 12-24V to 10


I have a tendency to stay away from these... wind blows specs change.. 
Lots of info here and nanoreef?
Walk through for modified Chinese black box for running on Apex - Page 4 - Reef Central Online Community


So bottom line is the TC-420 pulses the exact voltage you feed it.. modifying or not depends on this and what the add board takes to convert it to "analog"..

see the complication here?
















Sounds confusing...


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## Kampo

jeffkrol said:


> Technically yes..but that one doesn't list PWM voltage range it takes nor the PWM frequency.
> Also some Marsaqua's will do 10V PWM as well.
> . No guarantee on what driver or topology they use..
> 
> IF it can do 10V PWM you only need to add a 10V PS to the TC-420 and attach to the outputs. No modding necessary or add on board..
> The MOSFETS "pulse" the voltage you use on the supply side.
> A lot of drivers are "dual use" on the Dim circuit..
> I would probably try that first if you can find a cheap 10V switching power supply..If not there are plenty of cheap "voltage regulators" out there to drop your voltage from say 12-24V to 10
> 
> 
> I have a tendency to stay away from these... wind blows specs change..
> Lots of info here and nanoreef?
> Walk through for modified Chinese black box for running on Apex - Page 4 - Reef Central Online Community
> 
> 
> So bottom line is the TC-420 pulses the exact voltage you feed it.. modifying or not depends on this and what the add board takes to convert it to "analog"..
> 
> see the complication here?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sounds confusing...


thanks for the info!, questions answered more uncertainty lol! didn't know some used PWM, I know many modded them to use with an apex, but an apex used 0-10V not much talk on using them with PWM based controllers


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## jeffkrol

Well...10V PWM controllers (aquatic world) aren't very common.
Still a lot of conjecture.. and not giving it high odds..


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## Kampo

jeffkrol said:


> Well...10V PWM controllers (aquatic world) aren't very common.
> Still a lot of conjecture.. and not giving it high odds..


yeah more I dig more i'm not thinking its the best idea. either just deal with it as is or go another direction.


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## Ghiacciolo79

Whoa this thread is a life.saver! really usefull information and diagrams...
just a clarification, please: How do you do the "common ground" thing, exactly? do you mean that you connect together V- from both power supplies??

Thank you!


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## jeffkrol

Ghiacciolo79 said:


> Whoa this thread is a life.saver! really usefull information and diagrams...
> just a clarification, please: How do you do the "common ground" thing, exactly? do you mean that you connect together V- from both power supplies??
> 
> Thank you!











Yea.. the black dot...
The 12 to 24V isn't exclusive either.. 9v can be used and probably as low as 7v (who has a 7v wall wart..) but 5 doesn't work.. 
Amp output can be low..so nothing difficult there either...
Unless you are also running strips, it is easier to just add one of the cheap buck voltage regulators on eeek bay..
Connecting high power LEDs to the TC420
http://www.tc420.net/images/TC420/TC420-High-Power-LED-Circuit.png


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## Ghiacciolo79

Cool, thanks!

Yeah whit converter seems more straightfoward...i was perplexed by wiring togheter a 12V to say...a 24V. Planning to work whit just a single 24V ps anyway...

Right now i'm thinking a setup like this: 

4 channels of 5x 3.xV leds, each chain is around 17V at max 700mA whit a meanwell LDD

This way i could use a 24V power supply for both leds and TC420. Now...let's says i want to double the leds, for a total of 4 pairs of channels.
If i understand correctly, it would be possible to drive each 2x chain in parallel, so the Voltage stay the same, but the current doubles up.
So if i use a 1200mA LDD to power 2x channels in parallel, each channel will work at 600mA, right?
Do you think it would work this way or it would be better to double up the LDD drivers, so that a single PWM signal pilot 2x drivers?

Anyway---whit short chains like this (max x6/7 3V leds per channel), wouldn't be better to just run the system at the required voltage (17-18V) and use the TC420 whitout pwm hack? XD


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## jeffkrol

Series parallel causes problems if one of the strings open up. Then all the current goes to the remaining one..
In your case many would put like a 1A fuse on the strings so it blows b4 the remaining string blows.
If the diodes chosen can handle full amps then not necessary though it will increase heat output.
Separate driver per string is recommended and the most common method..At like $7 each certainly not a big cash outlay.

you can do w/out the driver alltogether at 12-24V as long as you use a terminating resistor on each string. Match Ohms and Watt rating.





> Solution 0: 5 x 1 array uses 5 LEDs exactly
> +24V
> +	-|>|-	-|>|-	-|>|-	-|>|-	-|>|-	-/\/\/\-	+	R = 10 ohms
> The wizard says: In solution 0:
> 
> each 10 ohm resistor dissipates 4900 mW
> the wizard thinks the power dissipated in your resistors is a concern Help
> together, all resistors dissipate 4900 mW
> together, the diodes dissipate 11900 mW
> total power dissipated by the array is 16800 mW
> the array draws current of 700 mA from the source.


1/3 of your watts is wasted as resistor heat..
USES 24v 700ma and a V(f) of 3.4

Better:




> Solution 0: 7 x 1 array uses 7 LEDs exactly
> +24V
> +	-|>|-	-|>|-	-|>|-	-|>|-	-|>|-	-|>|-	-|>|-	-/\/\/\-	+	R = 1 ohms
> The wizard says: In solution 0:
> 
> each 1 ohm resistor dissipates 490 mW
> the wizard thinks 1W resistors are needed for your application Help
> together, all resistors dissipate 490 mW
> together, the diodes dissipate 16660 mW
> total power dissipated by the array is 17150 mW
> the array draws current of 700 mA from the source.


Designing the strings to get as close to the ps as possible is advised. Less waste.. Less heat.
Main problem is you never really know the "exact" voltage of a diode and cheap ones can be all over the board..
any savings would be lost by using "binned" diodes and even those are a range.

Correct way would be to use a larger ps, 700mA constant current driver. Build the string. Run it till it is at max heating off ps and driver.
Measure voltage and then calculate how big of resistor will drop your actual 24V ps to that found voltage..

Or guess...


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## Ghiacciolo79

Thank you, Good Sir!

They should promote you to chief customer service at Tc420's company!! :grin2:

Never tought about adding resistors...but you're absolutely right: just a waste of power heating them up! Better stick to LDD...


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## ChrisX

@jeffkrol

Can you please explain why the TC needs to be modified to work with an LDD? Its not clear exactly what/why you are doing this.


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## Kampo

ChrisX said:


> @jeffkrol
> 
> Can you please explain why the TC needs to be modified to work with an LDD? Its not clear exactly what/why you are doing this.


the reason you need to mod it is that it lets you top the 5v PWM signal before its amplified by the mosfet.


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## ChrisX

Kampo said:


> the reason you need to mod it is that it lets you top the 5v PWM signal before its amplified by the mosfet.


I see, tapping logic level directly.

What voltage range does the mosft put out? 0-10v?


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## Kampo

ChrisX said:


> I see, tapping logic level directly.
> 
> What voltage range does the mosft put out? 0-10v?


the logic level should be 5V pwm if I remember right, jeff correct me on this?. the output is whatever the psu voltage is.


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## jeffkrol

Kampo said:


> the logic level should be 5V pwm if I remember right, jeff correct me on this?. the output is whatever the psu voltage is.


MOSFET is just a high speed switch using a gate signal to start conduction..The "specs" of th MOSFET determine how much current and voltage this is..
Yes it varies by power supply..









LDD-s have variable dim circuit voltages (in a range) and one of the reasons things like a bluefish mini will not work w/ LDD-L's..
Second part of the slightly more complicated story.. Switching frequency also plays into this..

But bottom line is using the logic "signal" to the MOSFET allows you to control LDD's
Both frequency and voltage are in range AFAICT.. Hopefully the Chinese won't screw this up..

NOTE the whole thing is to BYPASS the MOSFET really..
a fun after effect is a channel can then control both LDD's and constant current strips..

https://youtu.be/1qm_5w7DDuA

This is just using a manual dimmer but a tc-420 would be the same

TC-420 is really no different than most DIY Aduino based controllers


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## ChrisX

Just to clarify, the intercepted signal is 0-5V. But it is PWModulated... If the signal is 100% then it is identical to 5V (100% pulse width). FAIAP, it is just a 0-5V signal.

Related question.. Does the LDD driver require a PWM signal to control dimming, or would any signal in the 0-5V range work?

The mosfet amplifies that signal to some other range. 0-10V? I don't think that was mentioned in the thread. Or is it variable based upon the power supply used? Does that mean the ouput signal can be set to the power supply used? 0-10V? 0-15V? 0-24V?

I am trying to figure out what devices it would be capable of controlling. 

For instance, can it vary the output voltage between 0-24V and control a driver that supports triac dimming? (What current can the Mosfets provide?)
How about controlling fixed voltage (commercial) light bars by reducing voltage?
Can it (be made to) output in 0-10V range to control devices that support 0-10V dimming?


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## jeffkrol

Well ignore the MOSFET "output" It is to carry a load..

and the 5V PWM signal to the "gatE" is either 5v or ZERO in a pulsed fashion
This is what the TC-420 outputs to the MOSFET gate..and how it controls an LDD.
LDD will do all power handling. It Replaces the mosfet so to speak.









NO nothing here controls lights that do TRIAC dimming. 
MOSFETS themselves can "Pulse WIDTH dim any constant voltage array that falls in the 12-(more like 9 really) to 24 V range BUT only at a set voltage.. i.e only 12V arrays w/ a 12V ps hooked up..

The TC-420 only chops outputs doesn't change anything or boost anything.
(w/ the exception of an internal voltage regulator to feed the logic circuits (hence the 5V) but I digress)

SOME LDD's can use 0-2.4V analog dimming on the 5V PWM dim circuit..but as I said earlier .. sort of pointless.

suppose I need to clarify a few things:


> the intercepted signal is 0-5V. But it is PWModulated... If the signal is 100% then it is identical to 5V (100% pulse width). FAIAP, it is just a 0-5V signal.


the signal is digitall Instead of 0's or 1's its 5V or zero volts..
5V 50% of the time and 0V 50% of the time "looks like 2.5V but it isn't.
WHAT the 5V TO GATE signal looks like..










What the LDD output looks like in respose:


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## ChrisX

jeffkrol said:


> SOME LDD's can use 0-2.4V analog dimming on the 5V PWM dim circuit..but as I said earlier .. sort of pointless.


I disagree. I have designed (researched? discovered?) a way to control each R G B channel for pennies. Prototyping soon. 

It will be great to have analog knobs to adjust RGB that can later be upgraded to a programmable controller.


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## jeffkrol

ChrisX said:


> I disagree. I have designed (researched? discovered?) a way to control each R G B channel for pennies. Prototyping soon.
> 
> It will be great to have analog knobs to adjust RGB that can later be upgraded to a programmable controller.


Pointless if you add a TC-420 into the mix..

you can actually do the same thing w/ these:

Manual Dimmer Switch 12V 24V 8A 96W Single Color Knob LED Dimmer Controller for 3528 5050 5630 3014 Warm Cool White LED Strip Lights Mountab Dimmer Switch Dimmer 12V Inline PWM Online with $412.7/Piece on Etoceramics's Store | DHgate.com

If you buy 1000 they are only 36 cents each.. 
Plastic box, Rheostat, 555 timing chip, voltage regulator and asst ."bits".. 
*99 cents plus free shipping..142452693814*
Gotta love the Chinese..
BIN is $2 each.. free shipping..
White wire is a tap off the MOSFET gate inside.. See thread:









In all seriousness.. They are only a buck or 2 each and possibly cheaper china direct flea bay..
you do the same "hack" on them

http://www.plantedtank.net/forums/20-diy/1008498-manual-pwm-dimmer-ldd-h.html


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## ChrisX

Mine is better. Uses an Lm317 some resistors and a voltage divider. No shipping from china. Much smaller form factor. Costs less.


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## jeffkrol

ChrisX said:


> Mine is better. Uses an Lm317 some resistors and a voltage divider. No shipping from china. Much smaller form factor. Costs less.


analog dimming only works for LDD-l' in 1000 and 1500mA

Can't dim to zero either.. Drops out at 20%...

will be interesting though..


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## ChrisX

jeffkrol said:


> analog dimming only works for LDD-l' in 1000 and 1500mA
> 
> Can't dim to zero either.. Drops out at 20%...
> 
> will be interesting though..


If I need to run any one of the colors between 0-20%, that means I have too many leds of that color. They can be removed from the string.

Also, the output intensity of leds is likely not linear, especially that low in their range. I'm not expecting a noticable jump from 0-20%, but that is a potential risk.

Purchased 1200mA LDD-L. Two parallel strings of 700ma LEDs run @ 600mA. Balaced with current mirror. (My other drivers are 600mA so all leds run at same current.)

The net result will be a relatively high wattage RGB string controlled by three pots. Analog controls cost < $10 total. Can later be upgraded to TC if desired.

Once the RGB channels are in place, I can add other colors to the main array and use RGB to balance the look.


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## jeffkrol

0-20% is quite notceable but if you aren't "ramping" a channel yea not really an issue..
Want some expensive but fun color tune-able ribbons?
https://store.yujiintl.com/collecti...ibbon/products/high-cri-rgbw-4-in-1-led-strip


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## ChrisX

I'm DONE with strip lights. The light density is not as high, requires too much real estate. There are problems with heat management. 

I investigated using RGB strip lights (and their controllers), but all use a remote, most not tunable beyond 20 stock colors. And most run at fixed voltage.

From a usability standpoint, what I really wanted is just pots to control channels. I have all the parts for the prototype just need to find time. Once proven I can order the leds and power supply.


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## jeffkrol

ChrisX said:


> I'm DONE with strip lights. The light density is not as high, requires too much real estate. There are problems with heat management.
> 
> I investigated using RGB strip lights (and their controllers), but all use a remote, most not tunable beyond 20 stock colors. And most run at fixed voltage.
> 
> From a usability standpoint, what I really wanted is just pots to control channels. I have all the parts for the prototype just need to find time. Once proven I can order the leds and power supply.


Yea.. Don't blame you on that one. Actually mentioned it due to a mis-read of your above thread.


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## Kampo

ChrisX said:


> I'm DONE with strip lights. The light density is not as high, requires too much real estate. There are problems with heat management.
> 
> I investigated using RGB strip lights (and their controllers), but all use a remote, most not tunable beyond 20 stock colors. And most run at fixed voltage.
> 
> From a usability standpoint, what I really wanted is just pots to control channels. I have all the parts for the prototype just need to find time. Once proven I can order the leds and power supply.


you can look into rigid led strips. they are much more "dence" light wise and the leds seem to be run a bit harder since there on a aluminum backing. I have some I use in my fish room. 20inches 11 watts 1200 or so lumens run 1 of those per 10 gallons of tank. there pretty nice dual row one 3500k one 6500k. wouldn't be enough for anything super deep but for tanks you would use a planted + or simlar light on. work great.


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## sir.tie

Try bridgelux eb series strips, excellent performance

Sent from my Nexus 6P using Tapatalk


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## jeffkrol

UPDATE:

Lost one of the channels in the tc-420

I somehow lost a diode on the Cyan channel (cause or effect???) and for some reason the bypass gate wire is causing a malfunction..
At first thought I lost an LDD but that wasn't the case

Oddest part was when measuring no load voltage the gate voltage was 1.5 (should be 5) and the output at the diodes was 36 (should be 56V).......
So something "downstream" of the gate circuit is wonky..

Took too long to identify this problem I must say.
Have pulled the malfunctioning bypass wire and hooked it to ch5 (which was unused) but have yet to test it.. Kind of burned out on this atm...

Hooked up a Typhon as a substitute..

Just an fyi and will add more eventually.


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## jeffkrol

UPDATE..

Channel seems fine.. was a programming fobar.. 

So I mentioned was using only 4 out of the 5 channels..
Actually a long story............

Anyways got it back to functional.................


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## Ghiacciolo79

Hello i write back on this post after my failed attempt...hoping someone could help me sort thi out.

I've made the following project modding my TC420 to access PWM signals:



As per led's chains specifics, i've used meanwell LDD of 1000 1000 700 700.

This contraption worked (even for many hours), but i've encountered some problems, and in attemp to fix them...i've screwed badly! :crying:

1) the converter run very hot, and at some dimming levels i could hear a buzzing noise (from PSU i though)

SCREW UP #1

I thought: ok, maybe is the converter, so i've unplugged it from the circuit and powered the TC420 only whit a spare PSU trought the left jack connector...RESULT: half LDD bloated and fried! 

Reverting back to the converter, whit only half the drives the buzz was unoticeable...so i though: maybe the overall configuration is too much mA.

SCREW UP#2
I've ordered new LDD in the following configuration: 700 500 500 350.
Hooked everything back as per diagram, plugged the power in aaaand....

...BAM smoke and fried TC420:


Please HELP! (i'm planning to get another tc420 to mod or a storm contreller...but first i have to sort what kind of mistakes i've made)


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## jeffkrol

You are attaching the PWM wires to the correct spot.. right? Blue is where the 5V "feed" for the output goes to..









What you blew looks like (and am only guessing) is the transistor/resistor circuit to prevent too much current getting to the MOSFET gate
LDD's run at way less than 20mA on the LDD PWM wire..not sure how you could blow that but...you did..

Those wires don't "go to" the screw lugs.. but are independent from them..
Just in case..









Looks like you only blew out ch 4............

Your diagram is a bit confusing.. plus and munus to the TC-420 (12v) should only be on input plus minus of the tc-420..
http://www.tc420.net/connecting-high-power-LEDs-to-the-TC420.php


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## jeffkrol

Well you may be able to salvage it if you can carefully tap off the red points ..Should be the orig digital pwm "ports"
going to be one heck of a solder job..BT first things first









What you blew out..
http://store.alhekma4u.com/s8050-j3y-transistor-bjt-npn-25v-0-5a-0-3w-150mhz-to-23/


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## Ghiacciolo79

Thank you for your reply!

Yeah the wire were connected to the correct gate on mosfets...they run indipendently to ldd's.

If u find the diagram confusing, maybe i've just made an error there. Since my fixture have an onboard thermal controller plus a 12v fan, i thought to run a 12V line from the converter. Indeed, i've attached the wires of said line to the screw lug on the TC420. Now, the fan's 12V- definetely on the V- input, for the fan's 12V+ i dont remember...maybe on the V+ input or V+ output on the TC420. Could be that a big mistake?

what happened anyway was that:

1) the system had only ch1 whit LDD700 and ch2 whit LDD1000 inserted. the TC420 was dimming those at 25%.
2) i've plugged the power in. leds was running. I've heated up my heatsink and manually touched the screw lugs whit my fan's 12V line, just to test
3) Fan started to spin correctly for a minute or so.
4) unlugged the power
5) Plugged usb in and erased my configuration to put 3 new test modes (25-50-75%). don't remember in which mode the tc420 stayed.
5) I've screwed the fan's 12V line on the tc420. Changed the LDD configuration: Ch1: 500 Ch2: 500 Ch3: 700 Ch4: 350.
6) plugged the power back in--->blew up

Now the tc420 don't power up. neither by the usb port (the power led glows faintly then goes off) neither by the V input screw. 
Tested voltage: they seems ok. The converter output is 12V, but if the TC420 input are connected, it reads 3,4V


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## jeffkrol

Can't honestly say what the problem is but I'd start w/ just put the fan on a separate wall wart for now..
might consider replacing the dc/dc converter as well..


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## Ghiacciolo79

Yeah you'r right: better play safe and keep things separated.

I'm ordering a new TC420 and a new converter. My PSU is a Meanwell LRS-150W 36V (4,3A). Which one would you consider to power the controller?

https://www.aliexpress.com/item/DC-DC-Buck-Converter-4V-40V-1-2V-36V-8A-100W-Step-Down-Voltage-Power-Module/32760965074.html?spm=a2g0s.8937460.0.0.ykr6MA

https://www.aliexpress.com/item/300...-b0bc-4a63-84b3-db7b26512d8d&rmStoreLevelAB=5

https://www.aliexpress.com/item/100...-57e9-4026-a9cd-fc63be8c29f5&rmStoreLevelAB=5

Also...the PSU have two separate outputs (both 36V). Would be better to put all LDD on one, and use the other for the converter/controller or split the LDD between the two?


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## jeffkrol

Ghiacciolo79 said:


> Yeah you'r right: better play safe and keep things separated.
> 
> I'm ordering a new TC420 and a new converter. My PSU is a Meanwell LRS-150W 36V (4,3A). Which one would you consider to power the controller?
> 
> https://www.aliexpress.com/item/DC-...32760965074.html?spm=a2g0s.8937460.0.0.ykr6MA
> 
> https://www.aliexpress.com/item/300...-b0bc-4a63-84b3-db7b26512d8d&rmStoreLevelAB=5
> 
> https://www.aliexpress.com/item/100...-57e9-4026-a9cd-fc63be8c29f5&rmStoreLevelAB=5
> 
> Also...the PSU have two separate outputs (both 36V). Would be better to put all LDD on one, and use the other for the converter/controller or split the LDD between the two?


Like the first one w/ the knob but as to my own preference.. Like the ones w/ the digital readout and the different type capacitors..
http://www.elna.co.jp/en/capacitor/alumi/catalog/pdf/rvt_e.pdf
https://www.aliexpress.com/store/pr...ml?spm=2114.10010108.1000023.8.7b9cadd6FI8wxD

As to the power supply output ..doesn't matter.. the 2 sets of outs are for convenience w/ no real function..


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## Ghiacciolo79

Thank you!


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## Kampo

ended up going this route for my lights on my reef and planted. currently using it to switch a cooling fan on and off. but on TC420.net it hints at a way to control the fan speed instead of just on and off, any ideas of what that circuit might look like?


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## jeffkrol

Depends on how fancy or un-fancy  you want to get..
Theoretically the best way is to use the 5V PWM and a 4 wire computer fan.. BUT normally those don't like the low frequency of the tc-420


> PWM Control Input Signal
> The following requirements are measured at the PW
> M (control) pin of the fan cable connector see
> Figure 7 and Table 1:
> PWM Frequency: Target frequency 25 kHz,
> acceptable operational range 21 kHz to 28 kHz


Pretty sure that out then.....

Second just use 12V (or fan voltage) off the normal outputs of the TC-420 (use 12V power supply w/ enough current for the fans)in on/off mode w/ an in-line
thermal snap switch 
https://www.zoro.com/zoro-select-adjustable-fan-switch-90-130-6uee1/i/G3923787/

or even a temp dependent resistor circuit..
Temperature Controlled DC Fan









both w/ the "jump" function set

Third, just try using the normal channel and normal PWM. W/ luck the fan will interpolate the voltage as "less" ie. at 50% dim 12v looks to it like 6v..
Probably not a good way to do it..

anyways best is always temp dependent speed not time dependent..


----------

