# Slow ramp up and down led



## jeffkrol (Jun 5, 2013)

m_t_r_86 said:


> I've been searching and searching and cannot find something to fit my need. I want to slowly ramp my leds on and then when the power goes off slowly ramp down. I'm using a meanwell 60-48d with a 9 volt wall wart right now. The ramp times only need to be about 10-15 seconds. Each meanwell powers a 50 watt led chip (33volt @about 700mA). I can't find any type of circuit for that much of a power hog led. Most circuits I see are for 12 volts or less. I only want to do this so my discus stop freaking out when the lights turn off and on abruptly. Thank you.
> 
> I do have a couple 555 timers and a few hundred resistors and capacitors. Any input would be great.
> 
> Bump: I also have a few npn transistors too.



You "just" need to apply a 1-10V analog signal to the dim circuit.
That model was the first driver I used and dimming it is one of the reasons I went w/ LDD's and 5V PWM

Works fine w/ things like the Apex..not so well w/ things like Typhons, Storm(x), or any Aduino based controllers..

There are dozens of builds for Aduino and a handful of cheapish PWM controllers

your best bet is converting the 5V PWM to 0-10V analog.
Keep in mind it won't dim to zero (10% is your lowest stable setting) so your light will still "jump" to 10%.
Also requires a secondary timer to shut it off fully..

That said what you need is 1)Typhon.
2)on/off timer and a circuit like this:









DON'T think you can use a Typhon 10V PWM..won't work..

There are some pre-made boards to do this as well ..but I have no guarantee what does or doesn't work.
As I said above, cut my teeth on this but at the time didn't want to add more active circuitry (separate power supply to transistor/opamp) and stubbornly wanted all passive components..
'Almost" got it..long story..
Gave up went to LDD's never looked back.........

for fun:
http://www.reefcentral.com/forums/showthread.php?t=2318572

looking at that thread again pretty sure this is fully functional w/ any 5v pwm..









basically smooth the pm w/ a r/c circuit and double the voltage...


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## m_t_r_86 (Jan 10, 2016)

I understand I need a 1-10v supply to the dim circuit on the meanwell. I am currently running a9 volt wall wart to power that circuit.

My question is, without the use of a POT, how do I slowy ramp up/of my lights? Do I add circuitry to the 0-10v circuit or the LED output. To be honest, I'm not sure.

Bump: Also, I'm not trying to spend a lot.

Bump: Is there a way, using my 9 volt wall wart and some diy circuit to create a soft on off into the 0-10v dim circuit?


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## m_t_r_86 (Jan 10, 2016)

I don't think I'm fully understanding your second circuit layout. What is the 0-100% p1c and the random arrow coming off of the radiator at the top of the drawing? I understand the rest.

Bump: I would like to keep this nice and simple If it's possible.


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## jeffkrol (Jun 5, 2013)

m_t_r_86 said:


> I understand I need a 1-10v supply to the dim circuit on the meanwell. I am currently running a9 volt wall wart to power that circuit.
> 
> My question is, without the use of a POT, how do I slowy ramp up/of my lights? Do I add circuitry to the 0-10v circuit or the LED output. To be honest, I'm not sure.
> 
> ...


Well the above has the answer "except" for cost.
Typhon is about $45

Other than that.. possibly " something like this":
Just substitute 9V for the 22..

https://www.circuitlab.com/circuit/xw65e2/voltage-ramp/
Basically want to soft start the 9v........










Bump:


m_t_r_86 said:


> I understand I need a 1-10v supply to the dim circuit on the meanwell. I am currently running a9 volt wall wart to power that circuit.
> 
> My question is, without the use of a POT, how do I slowy ramp up/of my lights? Do I add circuitry to the 0-10v circuit or the LED output. To be honest, I'm not sure.
> 
> ...


 0-100% PWM is just from your PWM 'generator' like the Typhon.
in this case some British controller site/program (PIC)
http://www.picbasic.co.uk/forum/
Arrow at the top is for a variable resistor (pot) to trim the circuit so as to get the correct range out..Ends the need for precision components at that point........


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## jeffkrol (Jun 5, 2013)

2 more "soft start" circuits..................
Soft Start PSU


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## m_t_r_86 (Jan 10, 2016)

I like the first circuit quote a bit and looks to be the most practical. I do have a question about it. I noticed it said the voltage can be adjusted. How exactly? Is it just by the type of resistor I use or is the chip something I can preset? Thanks!


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## jeffkrol (Jun 5, 2013)

m_t_r_86 said:


> I like the first circuit quote a bit and looks to be the most practical. I do have a question about it. I noticed it said the voltage can be adjusted. How exactly? Is it just by the type of resistor I use or is the chip something I can preset? Thanks!


which one????
This?











> The circuit must be assembled on a good quality PCB.
> LM 317 can deliver only up to 1A 0f current.
> The input voltage must be few volts higher than the desired output voltage.
> Here the input voltage can be 18 or 20V DC.
> Capacitor C2 must be rated at least 30V.


BTW: I can point you in the direction but the nuts and bolts is really above my paygrade..
anyways there are dozens........









http://www.talkingelectronics.com/projects/200TrCcts/101-200TrCcts.html


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## m_t_r_86 (Jan 10, 2016)

jeffkrol said:


> 2 more "soft start" circuits..................
> Soft Start PSU


After further looking into the circuits, ice decided to go with the second one. But can you explain the equation at the bottom right of the diagram please. Would I be correct to assume T=time? What does the RC=??? Thanks again. 

I also ordered everything for it so I'm just waiting on everything to come in. Ebay says the 13th.




Bump: It just seems to be a more flexible circuit than the lm317


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## m_t_r_86 (Jan 10, 2016)

Also, what should my supply voltage be based on these equations? I'm obviously not going to get 9.0vdc out of my 8.4vdc wall wart. Even using the equation: Vo=2.77*(1+R1/R2). Because if I use a 2k7 resistor for R1 and a 1k2 resistor for R2 I get 9.0025vdc. Thanks.


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## m_t_r_86 (Jan 10, 2016)

Also, I think the equation is incorrect. According to the L200 voltage regulator data sheet, it should NOT read Vo=2.77*(1+r1/r2). On the data sheet it reads Vo=Vref*(1+r2/r1). 

I'm not sure which equation to use now. The first one looks to be the more accurate but the second one comes of 3 different websites data sheets and a manufacturers pdf.

Any ideas?

Bump: So o figured it out. In the drawn diagram jeffkrol provided, r1 and r2 were switched from the diagram from the L200 days sheet or vice versa. Either way, the equation is correct. I do understand the circuit and equations to go with it a lot better. Except for the bottom right equitation.


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## m_t_r_86 (Jan 10, 2016)

I do have one final question. Will this circuit work in reverse? Meaning when power is turned off, will it perform a slow off? If not could I add another resistor above but before c2 capacitor to adjust the rate of drain from the capacitor allowing a slow off? Ideas?


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## jeffkrol (Jun 5, 2013)

m_t_r_86 said:


> Also, I think the equation is incorrect. According to the L200 voltage regulator data sheet, it should NOT read Vo=2.77*(1+r1/r2). On the data sheet it reads Vo=Vref*(1+r2/r1).
> 
> 
> 
> Bump: So o figured it out. In the drawn diagram jeffkrol provided, r1 and r2 were switched from the diagram from the L200 days sheet or vice versa. Either way, the equation is correct. I do understand the circuit and equations to go with it a lot better. Except for the bottom right equitation.


p3/12
Ref voltage starts at:
2.77 "typical" w/ a 20V "input"..
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000053.pdf

Hmm.. problem may be you will start at 3v, which is about 25%.
That still may be a bit shocking....


> Adj. output voltage down to 2.85V


IF I remember correctly, you may be able to adj.current down (or voltage, forgot which). People use these to get max out w/ less than max dim.. i.e like 9V not getting you full current. 
In other words adj. here will get you 100% at say 9v (110 & 10V)
I suspect a bit of playing with this will drop current (brightness) below the normal 25%. You will have to play w/ this a bit I suspect..

As to soft shut down...???
A capacitor may work.. not sure how it affects the ramp up though..Making c2 large may do it..

Anyways, from data sheet:









As a minor word of caution: When I attempted a passive voltage doubler to dim my Meanwell w/ 5V to start I ran into a current problem. This meanwell requires more current than a, say, LDD which can see micro amps..
Point is you need to watch the current limiter so as to not go too low..
Like I said, I can "see" some "possibilities" of this but most is over my pay grade..


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## jeffkrol (Jun 5, 2013)

circuit using the lm317 would have been my choice. Vo down to 1.25V...............


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## m_t_r_86 (Jan 10, 2016)

jeffkrol said:


> circuit using the lm317 would have been my choice. Vo down to 1.25V...............


I'm glad you pointed that out. I did not think about the beginning voltage and agree with you. I need to be closer to 0 volts going to my dimmer input on my meanwell and the lm317 has the lowest starting voltage output of the 2 circuits. So I'm going to build both and see which one will be best suited for my leds. With the lm317 circuit, what is the equation to calculate puppy voltage? Also, after some research, the amperage need to go to the dinner input on the meanwell can be no lower than 40mA. Well this be a problem from either circuit? Thanks again for all the info.

Bump: And is that 5k resistor actually a pot?

Bump: Or a pnp transistor?


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## m_t_r_86 (Jan 10, 2016)

Would something like this work for a shift start?


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## jeffkrol (Jun 5, 2013)

http://www.ti.com/lit/ds/symlink/lm317.pdf

Go to 9.3.9
AFAICT just use > 12V power supply, change R2 to a 10 or 20K potentiometer and you can set final voltage to whatever you want.
I assume the size of c1 determines the timing..?


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## m_t_r_86 (Jan 10, 2016)

jeffkrol said:


> http://www.ti.com/lit/ds/symlink/lm317.pdf
> 
> Go to 9.3.9
> AFAICT just use > 12V power supply, change R2 to a 10 or 20K potentiometer and you can set final voltage to whatever you want.


I'm sold. This is exactly what I was looking for in the beginning. Thank you a ton. I'll let you know how it works when I get it together.


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## jeffkrol (Jun 5, 2013)

I have been "schooled" that it is much easier than that.. 
RC Charging Circuit Tutorial & RC Time Constant

Only problem seems to be the longer the time period the less current is available..
Oh well, the others look much more fun...........


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