DIY LED driver for reef lighting

[terahz]

I didn't state that they were. I was referring to the multiple reels of 4,000 contacts that I buy a few times a year.

My apologies, misunderstood you.

 

[Porgy Bait]

Thanks terahz for the link to FindChips. Its like Google for chips. I will be using it for future projects. Man I wish they had it back when I went to school it would have made life a bit easier.

 

[MaLi]

Greetings,

does anyone have some extra pcb for TeraHz schematic (Arduino I2C commanded) ?
PM please.

cheers,
MaLi

 

[Landsailor]

A couple of spreadsheet related questions for the LM3409.

How do I pick the Output Voltage of these 10W chips when the Vf is listed as "10-12"? It would be great if I could use one of these 24VDC power supplies we have laying around the shop.

What's a desired Switching frequency?

Thanks,
Jason

 

[Landsailor]

Double post deleted.

 

[Aqua@Home]

Can anybody share me the pot controlled PWM circuit diagram for dimming the led. I wanted to use it with either CAT or LM IC's.

 

[O2Surplus]

Can anybody share me the pot controlled PWM circuit diagram for dimming the led. I wanted to use it with either CAT or LM IC's.

Aqua@Home, use a 10k pot and 549ohm resistor with the CAT4101 and a 250kohm pot and .1mf cap with the LM3409. I've attached a couple of diagrams for you, good luck with your drivers.

 

[Aqua@Home]

O2Surplus, thanks for providing the circuit diagrams. But I have a small problem here. I already have the pcb done for the CAT4101_triple_separate_PWM with me. I have 10pcb's with me for the CAT4101_triple_separate_PWM.

Hence I think, I would not be able to apply the design you have provided for the cat IC. I could solder the pot wires to the resistor track. But it would be too risky to do in the smd track!!!

Is there any other circuit diagram, which I could use? I tried using the 555 pwm circuit but no success

 

[rrasco]

O2Surplus, thanks for providing the circuit diagrams. But I have a small problem here. I already have the pcb done for the CAT4101_triple_separate_PWM with me. I have 10pcb's with me for the CAT4101_triple_separate_PWM.

Hence I think, I would not be able to apply the design you have provided for the cat IC. I could solder the pot wires to the resistor track. But it would be too risky to do in the smd track!!!

Is there any other circuit diagram, which I could use? I tried using the 555 pwm circuit but no success

I built a circuit I found online, but it didn't work very well. Any reason you don't want to use something like an Arduino? That makes it a lot funner and adds a ton of capability. I wanted the pot controlled generator for a temp setup, everything is now run off an Arduino and I couldn't be happier.

This is the circuit I used: http://pcbheaven.com/circuitpages/LED_PWM_Dimmer/

http://www.youtube.com/watch?v=YnLa-hY74q4

 

[Aqua@Home]

I built a circuit I found online, but it didn't work very well. Any reason you don't want to use something like an Arduino? That makes it a lot funner and adds a ton of capability. I wanted the pot controlled generator for a temp setup, everything is now run off an Arduino and I couldn't be happier.

This is the circuit I used: http://pcbheaven.com/circuitpages/LED_PWM_Dimmer/

http://www.youtube.com/watch?v=YnLa-hY74q4

I am a physics graduate and a big zero in programming :spin2: :headwally:

But I know electronics as my special subject was electronics

Hence was trying to make a circuit based PWM (analog) to dim the led through the cat4101.

 

[rrasco]

I guess I have the advantage of being a developer, but there are tons of resources here on RC that you have to help you program your controller. Once I had my LCD, temp sensor, and RTC working...I pulled code from some threads here and had my lights ramping up/down flawlessly within an hour. Not only was it fun, it's amazing watching them ramp down at night.

 

[ZenMastr1968]

Thanks DWZM.... I was trying to re-read the whole thread to figure out where things currently stand. Now I know

My Hydra has been itching for something more important to do for awhile and I had been saving up for a Cree retrofit for the BC29 I setup last year....since I now have the money and nanotuners isn't an option, I'm back onboard here.

I'm looking to build a 24 led array - not sure how many strands of which color yet . Have seen some good builds along this line and am still looking for a driver to fit my needs. I want to do sunrise /sunset dimming via Hydra (pwm), but want the leds to go completely off. I think I remember reading in this thread one of the designs could do that (I was told that meanwells could only go down to a certain point and then you had to kill the mains so I gave up that route). Is that still true and if so which design?


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Both of the chips mentioned above are capable of full shutdown via the PWM dimming input. In fact that's how I am running things on my tank. If you use terahz's LM3409 design make sure you get the latest version as earlier versions didn't shut down correctly when operating with analog dimming.

In your case it will probably come down to how many different strings you have and if their Vfs are similar. If you end up with lots of different colors at lots of different Vfs the CAT4101 is a pain because it's hard to tune a single DC supply to cover a wide range like that. So you might either have to use several DC supplies (not the end of the world) or use the LM3409 for some or all of your strings.

Thanks, I'll sort out my strings and/or colors and see where that "LEDs" me....:lol2:

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Ok, back from the depths of obivilion...

My stock lighting has Sh%%%%%t the bed recently and I've pulled the trigger on the rapid LED dimmable retro kit for the BC29. I know it has the meanwells in it - which I was against, but needed a kit that would get me light again as soon as possible and wasn't interested in trying to repair the PC fixture in my hood. I'm only planning on using the meanwells long enought to get a suitable driver from here built and operational....

With that said, as previously stated, I have a Hydra and want to do sunrise/sunset dimming. The kit is supposed to come with 12 RB Cree XT-E and 12 Cool White Cree XP-G. I'm sketchy as to how to figure out the needed voltages and/or strings - I think the RB XP-E should be run around 800mA and the CW XP-G around 1200mA, so that tells me I need at least 2 drivers (besides the fact that I would want to dim w vs b anyway) because of the current differences. Are there any other factors that effect this?

I'm not 100% sure what I'm asking, but where do I find the calculation infomation to figure out how many of the XP-E and how many XP-G can be in a given string and how many drivers I'd need for those strings?

TIA and another great job to all that have contributed to this project.

 

[TheFishMan65]

You will be fine with 12 one a string. You may want to stop here

The number maximum on a string is tricky. First start with the supply voltage 48 volts for the ELN (usually). Then you have to guess at the current you will be running them. Then go to the datasheet and see what voltage that corresponds to. The typical LEDs we have been dealing with will have a voltage drop of 3 to 3.9 volts (IIRC). So somewhere between 16 (48 / 3) and 12 (48 / 3.9)is the maximum.

You must meet the minimum voltage of the ELN (27 volts IIRC) so do not use less than 9 (27 / 3) and you will be safe.

 

[ZenMastr1968]

You will be fine with 12 one a string. You may want to stop here

The number maximum on a string is tricky. First start with the supply voltage 48 volts for the ELN (usually). Then you have to guess at the current you will be running them. Then go to the datasheet and see what voltage that corresponds to. The typical LEDs we have been dealing with will have a voltage drop of 3 to 3.9 volts (IIRC). So somewhere between 16 (48 / 3) and 12 (48 / 3.9)is the maximum.

You must meet the minimum voltage of the ELN (27 volts IIRC) so do not use less than 9 (27 / 3) and you will be safe.

Thanks FishMan - that is similar what I calcuated. I want to drop the meanwells and switch over to either the LM3409 or the Cat4101 drivers.

My equation went like this....
for whites: XR-G ~ 3.2V forward voltage at 1000mA
So 12*3.2 + .7 + .35 = 39.45 {i read somewhere to add in the additional drops}
that meant I'd need a 48 v supply to run that string.

for blues: XT-E ~ 3.1V forward voltage at 750mA
So 12*3.1 + .7 +.35 = 38.25
also a 48 volt supply

So if these numbers are close - which flavor driver would be better for this situation? I read that the cat worked better if the input closely matches the output, so would these be close enough to run both strings off the same power supply?? I suppose the blues could run with a higher current to more closely match the whites and dial down the 48V PS to 39V. I haven't looked at powers supplies yet, but is that too much of a drop??

Or would it be better to just use the LM chip and let them run at the amps I want them to???

Thoughts?

 

[O2Surplus]

Thanks FishMan - that is similar what I calcuated. I want to drop the meanwells and switch over to either the LM3409 or the Cat4101 drivers.

My equation went like this....
for whites: XR-G ~ 3.2V forward voltage at 1000mA
So 12*3.2 + .7 + .35 = 39.45 {i read somewhere to add in the additional drops}
that meant I'd need a 48 v supply to run that string.

for blues: XT-E ~ 3.1V forward voltage at 750mA
So 12*3.1 + .7 +.35 = 38.25
also a 48 volt supply

So if these numbers are close - which flavor driver would be better for this situation? I read that the cat worked better if the input closely matches the output, so would these be close enough to run both strings off the same power supply?? I suppose the blues could run with a higher current to more closely match the whites and dial down the 48V PS to 39V. I haven't looked at powers supplies yet, but is that too much of a drop??

Or would it be better to just use the LM chip and let them run at the amps I want them to???

Thoughts?

The CAT4101 chip is only rated for 25volts, so you'd be limited to 6-7 leds per string with that one. The LM3409 is rated for up to 42 volts IIRC and the LM3409HV can go as high as 75volts. The LM3409HV will be the best choice for driving long strings of leds. You can always go "overkill" with your design in respect to output current and then turn it down, using the Iadj pin and a pot, to suit your needs.

 

[ZenMastr1968]

The CAT4101 chip is only rated for 25volts, so you'd be limited to 6-7 leds per string with that one. The LM3409 is rated for up to 42 volts IIRC and the LM3409HV can go as high as 75volts. The LM3409HV will be the best choice for driving long strings of leds. You can always go "overkill" with your design in respect to output current and then turn it down, using the Iadj pin and a pot, to suit your needs.

That's what I was thinking, so I put though an order for 2 sets of the HV bom this afternoon. I know those are for 1amp, but I think that its only a few component changes to alter and I'm pretty sure I saw THz post a lower amp version somewhere in the thread - I'll have to keep looking for it.

One other question, what are the options for a 48v PS? I saw some single output mean well brand ones that were rated at 2 or 5 amps for about $45. Would that be a good choice?

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[O2Surplus]

One other question, what are the options for a 48v PS? I saw some single output mean well brand ones that were rated at 2 or 5 amps for about $45. Would that be a good choice?

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Check FleaBay. You can find them new for around $60 for a 7 amp model. I found a couple of "gently used" units for $30 apiece. Just be patient and don't fall for the cheap prices advertised by suppliers from China. They advertise MeanWell, but they'll sell you a supply made by a company called MengWell and claim it's the same company. Genuine MeanWell supplies come from Taiwan.

 

[ZenMastr1968]

Thanks O2, it seems like a 5 or 7 amp supply would be overkill, but in the long run would that run cooler since it wouldn't be working as hard?

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[ZenMastr1968]

And given that line of thinking, would the HRP-300-48 be a good choice?

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[O2Surplus]

And given that line of thinking, would the HRP-300-48 be a good choice?

I couldn't find a listing for that part number,but this is what I use. It's slightly more powerful than the one you listed. Look for a MeanWell S-320-48. It's rated at 6.5 amps. I'm running 5 strings of 12 leds each @ 1000ma with no problems.