LED Safelight

Hi,

Those Jobo led safelights, are they using amber or orange leds? I

would like to build one with more output.

Thanks,

Jacques

I don't know about the Jobo, but I build one using a 24 LED package from Lumex. The leds were 590nM, a perfect match for the Kodak OC filter. I used 3 of the packages and it's bright enough for my darkroom.

HI, most led safelights use amber leds @ 590nm wavelength.

If you check the paper specs you'll see that B&W papers aren't sensitive to this light. Spectral sensitivity curves of coulour papers show the same. They tend to be less sensitive around 590 nm.

The main advantage of leds is that they are calibrated to emit light on a single wavelength ( +/- a few percent ). I built one safelight driven by an H-bridge PWM to dimm the output power. I made columns of 5 leds and one 100 ohms resistor in serial X 8 raws. With 40 leds I have enough light for my little lab. I used Agilent high output amber leds 30° diffusion angle. I put a pot to select from 10 to 100 % power output and work fine with any kind of paper. I tested it by putting pieces of paper for 5 minutes in the lab and develloped them. No fogging !