High Voltage Driver w/ DMX for a large array of Luxeon rebels

[reeformadness]

I want to develope a large array containing 270 luxeon rebels (driven at 350mA). I know its huge. On top of that I want RGB color control for the entire thing. I think DMX might offer the simplest solution. Currently, the only board I know of that is reasonable for this is the Quadpuck (w/ 4 1000mA buckpucks). However these are $160 and only drive 72 (I think) LEDS. So I'd need four which would be $640. More than I want to spend. Does anyone know of any cheaper alternatives to the quadpuck? Keep in mind that I am not an electrical engineer, so designing my own circuit is pretty much out of the question. I am looking for the simple interface of the quadpuck at a lower price. Any help will be appreciated.

 

[frenzee]

What is supply voltage?

 

[reeformadness]

I am not limited to a particular voltage as far as I can see. I was thinking I would send 24VDC to the drivers, but will do whatever works best. The unit will be plugged in to 110VAC.

 

[infinity of zero]

How safe does it have to be? Is it possible that someone would touch a led or the pcb?

When this can't happen the easiest way is to use a rectifier, a capacitor and a resistor for each string of leds. To controll the intensity you can add a Power mosfet so you can PWM them.

 

[reeformadness]

It needs to be relatively safe. No one would be touching the LEDs or PCBs, but it would be used around water (obviously, it would be enclosed to prevent getting wet). But, it would be marketed for sale to the general public, and I wouldn't want to sell anything that has the risk of electrocuting customers. Once again, I need something that would be easy for a novice to wire. I've done some research into constant-current, PWM, and the various topologies, and even calculated what compenents I would need, but in the end, I decided that I better not try and design my own circuits. This array needs to be as efficient as possible for it to be worth my while, since it will be competing with fluorescents and metal halide lighting. I think it should be left to professional engineers to design the circuitry since this will be a commercial product. I'm not wanting to reinvent the wheel. In addition, I want this thing to be DMX controlled, which would add even more complexity to the circuitry. Its beginning to look like the quadpuck might be my best option.

 

[snarfer]

I think you will have a hard time trying to develop a viable product based on current commercially available drivers. Power supply companies have been very slow to develop products with the necessary high forward voltage for driving long strings of LEDs.

Depending on the requirements of your precise application you might also need a color feedback circuit.

If you do find a product that works for you, be sure to let us know about it. I asked a similar question in a thread several months ago and nobody could come up with anything either. I also made some inquiries into custom solutions, but the cost would have been prohibitive.

If I were you I would scale down my concept and perhaps make it modular so you could attach several together.

I did look at the quad buckpuck solution, and noted that you could drive 72 LEDs with it, but only if you drove two parallel strings per puck. So that might be problematic if you had uneven heating of your array. I don't really know much about Rebels actually, maybe someone better informed could correct me on that. I ordered some a while back before they had that factory glitch, and they still haven't arrived, so I've moved on to other products.

 

[mds82]

Philips makes their Xitamium driver that can power up to 54 1 watt LED's

http://lampsandgear.com/gl_en/global_sites/led_lighting/downloads/tech-details-leddrivers.pdf

no idea on the price for this driver however.

 

[snarfer]

Looks like the Xitanium driver runs off 217-264 volt power only, but the OP wants to use 110 volt.

Also would have to run the LEDs in 6 parallel strings:

"Special attention is required for parallel arrays in case of Vf differences."

Whatever that means.

And it does not have a dimming function.

 

[jtr1962]

It needs to be relatively safe. No one would be touching the LEDs or PCBs, but it would be used around water (obviously, it would be enclosed to prevent getting wet). But, it would be marketed for sale to the general public, and I wouldn't want to sell anything that has the risk of electrocuting customers.

In that case you really can't run the LEDs in series strings of more than perhaps three or four. Even 24 VDC isn't really safe around water. You need to limit your output voltages to about 12VDC above or below ground. In other words, there is no easy AND safe solution. Best bet is 90 groups of 3 in series. Get a driver board which accepts PWM, and parallel the PWM inputs for each color. Each color would need 30 boards. Use step-down boards and use 12VDC for the raw power supply. By my calculations you'll need a 12VDC source capable of supplying on the order of 30 amps.

 

[snarfer]

Great point about safety. I've heard that salt water is especially conductive.

Maybe something like this would do the trick:

http://www.asiansignals.com/Fixtures.htm

Has DMX, dimming, circuits of 3 LEDs, Fan, runs on 12 volts for safety, and reasonable pricing too.

 

[Black Rose]

Looks like the Xitanium driver runs off 217-264 volt power only, but the OP wants to use 110 volt.

I wonder if those specs are for Europe.

Look here, and you'll see that the 40W, 1750mA driver is shown as 120VAC.

 

[Mash]

Xitaniums come in US or european voltage versions.
However some of their new ones are universal voltage capable.
The problem with your situation is that to drive a large series array, you need a corresponding large voltage. SO for arguments sake of saying 4Vs for one LED, for 270 in one circuit you are looking at 1080Vs!!!! Not very safe, and not very easy to work with, you probably would need an industrial scale electrician/cables/connectors etc! And think if you ahd a short somehwere in there!
Thas why you will see that most manufacturers prefer to make higher current output drivers, which can be split into parralle circuits, rather than making higher max voltage drivers.
Also you seem to need DMX. SO your best bet would be to search for the highest powered DMX compliant driver, get as many of them as needed and control them all through one single DMX controller.
EG a quick google turned up this one that can drive 12channels of 5 LEDs http://www.megaled.com/LED_Controller_12ch..html
their stuff seems to be scalable, eg they have a 36 channel system which if each channel can drive 5 LEDs, you are looking at 180 LEDs from one driver. No idea of their pricing/reliability/quality; just something I found between google, and my saved bookmarks!
Hope this helps!

 

[snarfer]

SO for arguments sake of saying 4Vs for one LED, for 270 in one circuit you are looking at 1080Vs!!!!

Actually the OP said he needed RGB dimming, so there would have to be at least 3 strings. Also I believe the Rebel at 350 mA is closer to 3.2 volts forward voltage. Of course you are correct in that this would require higher voltage than is usually present in systems we talk about on this board. But still it is actually less than 300 volts, so a custom solution that could be implemented would be to run 3 high voltage buck controllers off of a standard PFC module.

Megaled is an interesting link. I wonder about their prices though. Looks like their latest project was a system for Sultan of Brunei. Not a good sign if looking for a cheap solution!

I don't buy your safety argument regarding why manufacturers haven't implemented higher voltage drivers yet. Fluorescent ballasts output much higher voltages, and they aren't necessarily isolated either, so what's the big deal?

 

[Oznog]

How are you mounting this many Rebels?
Gotta see this one.

The Supertex stuff- HV9910, much better idea is the HV9931- would do well but these are control chips not a controller. What kind of budget did you have?

 

[TigerhawkT3]

Based on $640 being more than you want to spend, I think that just the Rebels will blow your budget. To be less than $640, you'd have to get each emitter for less than $2.37, and that doesn't include drivers. The cost, complexity, and safety considerations for something like this are way above normal. Unless you already have customers lined up to pay a bundle for this, I'd recommend reconsidering this project.

 

[mds82]

Not to burst your bubble, but you may want to just get a bunch of florescent tubes, they will get you a lot of light and they are rather easy to setup too.

 

[LED-FX]

Reminds me of the Kiloled, not nuch furrther than press release heard of it since:

http://livedesignonline.com/gear/lighting/kiloled_from_easilyled_dot_com_050207/

Heck, fluro tubes, why didn`t I think of that , hey we can all just go home now...

Adam

 

[Oznog]

Maybe something like this would do the trick:

http://www.asiansignals.com/Fixtures.htm

Has DMX, dimming, circuits of 3 LEDs, Fan, runs on 12 volts for safety, and reasonable pricing too.

Wow, 36 Rebels! Whether this puts out good efficiency and lifespan, or works at all, depends on thermal design.

The problem is, that with AsianSignals, we had a previous discussion on their 6x board (look in the middle, it's not the 6x I made at the top). I could not see ANY way it had adequate thermal design. Not even close. *If* that same AsianSignals person designed this DMX thing, it's a piece of junk. See Luxeon's thermal filled-PTH concept requires a few mm around each thermal pad to make enough PTHs to conduct to the backplane. There is no such room in the DMX board.

But it's still possible that that disk in the middle (or the whole board) is a proper thermal-core PCB which is much much BETTER than the thermal PTH principle. So I'll be fair and give them the benefit of the doubt, but I sure wouldn't give them a lot of money before finding out for sure.

 

[snarfer]

I sent an inquiry to Asian Signals about some of these products. Got quite an extensive reply.

Regarding the 36 Rebel board:

The 36 Rebel board is not currently ready. I'm conferring with the first customer of that product to make a final decision on the LED placement. We may opt to remove the funnel style reflector and lens and spread out the LEDs a bit. That answer will be made fairly soon and we'll complete the layout and produce the board.

That board also contains a micro-processor, 2 digital temp sensor, and optional fan controller/driver circuit and traces to include an option for a light sensor and motion sensor (we can add functionality for those customers who might wan to use it).

The 4 pin connector is 12v+, Ground, controller fan ground, and the last is a one wire feedback circuit that communicates back to the main system.

I doubt that for 35 USD they are going to sell a board with thermal core PCB. If they were they would certainly have mentioned it!

Maybe that's why the board is being redesigned...

I don't see why it wouldn't be possible to make a design with proper thermal characteristics by using 4 oz. copper, very thin FR4, and lots of vias. Certainly cheaper than MCPCB.

Well anyway I don't want to speculate too much regarding the quality of their engineering until I have a look at the actual hardware. It wouldn't be fair. I asked them to notify me when the board is ready so I can order one and have a look. They are located in Northern Thailand, not too far from my girlfriend's hometown actually. So if it sucks I can go there and tell them to give me my money back!

 

[coolwaters]

since your planning on 270 LEDs i dont think buying a bunch of constant current units is the way to go. that stuff is expensive.

try moding a computer power supply. around 350w will cost less then $30.
(80%+ efficient will be in the $50s)

look for some wide voltage range regulators from DX or KD.
KD used to sell highly efficients boards for $3 and it can power about 10 LEDs at 350mA. but cant find it anymore.

also you can try looking for DIY regulators to make it cheaper.