Help converting cold light Graflarger to LED

[Tim Meisburger]

Well, I finally did it. This morning I accidentally connected my 120v Graflarger to the 220 mains and fried it. I pulled it apart, but it looks rather hopeless, and to replace the cold light head and starter is probably more cost than its worth.

So, I could probably hack up a holder for a couple of compact fluorescent bulbs or, it occurred to me, I could mount LEDs in the original housing. The compact florescent would give me two circular sources and might create round hot spots, but would be easy, while the LEDs could be mounted in a rectangular pattern, but I have never used them.

Any advice?

Also, can anyone point a spot meter at an enlarger light source and give me a reading? That will help me determine how much light I need.

[SMBooth]

Here a start
http://www.apug.org/forums/forum43/9...eds-100-a.html

[Tim Meisburger]

Thank you. I saw that, and it convinced me its possible.

Best, Tim

[vinny]

[/QUOTE]
Also, can anyone point a spot meter at an enlarger light source and give me a reading? That will help me determine how much light I need.[/QUOTE]

No, it won't. You need an incident reading at a certain distance from the light source.

[Leigh]

Be careful of heat. Graflargers aren't very big. High-intensity LEDs can generate significant heat.

You'll probably need a heat sink or a baffled forced-air cooling arrangement.

- Leigh

[Tim Meisburger]

Thanks Vinny. I think if I could read the diffusion glass at a particular distance and match that with a new light source I would be in the ball park, but I may not need it now. I have been reading more and one article said an enlarger bulb is 150 watts. If that is correct then I would need about 15 watts of LED to match the light output.

Leigh, that's interesting. I know nothing about LEDs, but some things I read say they are cool, and others say they are warm. One article said they put out a tenth the heat of an incandescent bulb, but even a 15w bulb would be too hot for the cold light box from the graflarger, so I guess if I use LEDs I'll have to make a new box. I would have to do that with the compact fluorescent as well.

[Leigh]

Hi Tim,

LED technology has made great advances in the last few years.

Old-tech LEDs produced very little light, and dissipated very little power.

New-tech "high-intensity" LEDs produce much more light, and dissipate much more power.

You really need to consult the manufacturer's datasheet for the LED involved
and do a thermal analysis of the design to determine cooling requirements.

- Leigh

[jp]

I haven't done it yet, but I'd look at some LED light panels on ebay made for video. They are available in a variety of rectangular sizes, many of which should be fine for 4x5.

[Steve Smith]

Have another search around APUG. There are a couple of posts about my DeVere 54 conversion using the LED PCB from an LED stage light. If I find them myself, I will post the links.

EDIT: (links)

http://www.apug.org/forums/forum43/7...nlarger-3.html

http://www.apug.org/forums/forum43/7...ht-source.html

http://www.apug.org/forums/forum43/7...ht-source.html

http://www.apug.org/forums/forum43/7...ad-update.html

Steve.

[Tim Meisburger]

Thanks Steve. That is useful!