Light emitting diodes

[RW Hawkins]

so, how much cash do you have invested in the project?

The LEDs were $160 at ledsupply.com, the power supply I picked up for ~$30 at a local electronic surplus store.

I'm a B&W printer so didn't worry too much about color temp other than to get it "white". My testing and research showed that it is not currently possible to get a true 5+ contrast with a color LED, so I am happy to continue to use Ilford contrast filters.

[Steve Smith]

And if you know how to program you can take an arduino board with PWM programming to light the leds in such a way that you can go from grade 00 to grade 5 without changing the exposure time.

That's one way but I don't like over complicating things. Just varying the current limiting resistors is a simpler way.

If I ever get round to making a variable controller for mine it will use PWM to vary the green from 0% to 100% whilst inversly varying the blue from 100% to 0% with a single control but there will not be any kind of programmable device in there, just simple electronics.


Steve.