Build an LED light pannel

[ShaolinWood]

Hi,
I want to build a light pannel that contains roughly 40 Bright white LEDs, and it should be powered by a portible powersource, like a 12V battery that I can stick in a backpack or something.

I will use it with my video camera, and want to mount it on my camera as a camera light.

I thought of making a circuit board and stick all the LEDs in a grid pattern, but I'm not sure what the right angle to build this will be.

can anyone give me any tips? Or have a nice DIY instruction site where I can get instructions on some of the aspects of doing this will be?

Thanks in advance for any help.

 

[ShaolinWood]

Also, what kind of resistor(s) will I need to use, if any?
Thanks

 

[itsmoked]

This really isn't a weekend kind of task. I have built a few and been quite disappointed with the result. I built circuit boards and a switching supply to convert a large lead acid flashlight to LED. 88 of them if I remember correctly. You could read a newspaper with it. But video?

Check another currently running thread on exactly this topic.

thread240-155801

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ShaolinWood]

Hi itsmoked, Thanks for the reply.

the kind of thing I have in mind will be something like this:

http://www.litepanels.com

It can run on the camera's power source, and emmits a LOT of light... I would just buy one of their's but it's REALLY expensive, and i thought there should be a way of constructing a similar light...

I'll go through the other forum now as well.

thanks

 

[itsmoked]

Let us review ShaolinWood;

You need about 160 LEDs x $1.50 = $240.
You need a circuit board to mount them on.

A bunch of LED Drive chips. Say one per four LEDs. 40.
$2.00 per device. $80

8 Hrs of layout and schematic capture. (If you have these tools/abilities)

6 Hrs of enclosure hassle.

$120 for one Board fab.

So we are at $440 not including any labor.

How much do you think is too much???

I tell you you can get way more bang for the buck with halogen lamps!! And better light quality to boot!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ShaolinWood]

Thanks itsmoked,

Yea I've been thinking the same thing now...
the only reason I thought of going LED was that it doesn't get so hot, and it has a soft light...
But I guess I'll be better of making a diffuser for the halogen lamp.

Thanks for the help though

 

[MacGyverS2000]

Wow, I'm just feeling so useful this week

First off, it's a misnomer that LEDs don't dissipate heat. They do, but most people are used to single 20mA Radio Shack deals, so the heat is for all intents and purposes nonexistant. When you move up to the larger LEDs (1W, 5W, etc.), heat dissipation becomes a major issue.

Is this for close-up or distant camera work? Close-up is best, or distant within a tight area. For close-up work a large viewing angle LED will be best (60-90 degree), for distant spotlighting you'll want something much tighter(something in the 10-30 degree range would be best).

I do not know how much power those plug-in halogens suck down, but you need to be careful running this off of the same battery as the camera. That being said, you will more than likely get a higher efficiency out of the LED versus the halogen if the conditions in my last paragraph are met.

Keith's cost breakdown is a bit overpriced, IMO, so here's my breakdown. Luxeon 1W white LEDs (

http://www.Luxeon.com

, just do a Google search on Luxeon and you'll find plenty of resellers) can be had in qty. 1 for about $5, less in bulk (say 10). For a 12V battery, I'd say put three of these in series.

For a driver, stay away from resistors. You need current control, and voltage regulators already have that functionality built in. Pick up a 12V regulator, like the LM317 ($0.50?), and connect it up as a current regulator. To do this, instead of connecting the ground pin to ground, connect it to the output through a resistor (I'll leave the value calculation for later). Now, no matter what voltage your camera battery drops to (within the range of the LEDs), the LEDs will always get the same amoun of current, say 200mA.

For heat dissipation, mount the LEDs to a metal heatsink, but if you keep the current low enough the metal core board they come on will more than likely do enough cooling without any extra help.

Board layout is now a 30-60 minute job. Proto boards can be had cheap, if you know where to look. Try out

http://www.BatchPCB.com

, it's a $10 setup fee + S/H and $2.50/square inch... for small boards, it doesn't get any cheaper than that. If the board comes up larger, but you can keep it one-sided, go to

http://www.MyroPCB.com

and get their one-sided proto for $20 + S/H.

I imagine with two strings of 3 series LEDs, a PCB, and regulator, you're looking at well under $100. Let us know how this one turns out.

Oh, and my comments about LED spectra and CCD cameras from the thread Keith linked to still hold...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[machmech]

I have been watching my son build a brake lite system for his hot rod out of LEDs. Ugh! all that soldering drilling and put-sing, he has one side done and has not touched the other side for two weeks now.

Good advice from Keith.