LED color mixer

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net.thi...@gmail.com

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Sep 14, 2015, 5:10:01 PM9/14/15
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I've attached some pictures of the LED color mixer I designed.  As Joe predicted, three volts were needed for each LED.  The red LED didn't light up with a 1.5 volt battery but it was able to handle the 2032 battery without failing.

This design uses 10K potentiometers.  Do you think it would work better with 1K potentiometers?  I'd like to see a smoother variance between the minimum and maximum brightness, but I'd also like to be able to turn the LEDs almost all the way off and I don't know how dim they will be with 1K of resistance.

I'll be building these for people at Ingenuity in exchange for a small donation to cover supplies.

Suggestions for diffusing covers are welcome.

Thanks,
Michael

rgb_mixer_1.jpg
rgb_mixer_2.jpg
rgb_mixer_3.jpg

Torrie Fischer

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Sep 14, 2015, 10:49:13 PM9/14/15
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10k pot should work fine.

If you want a smoother variance, you'd want to use some sort of transistor
with a microcontroller that can pass your pot through some math function.

While the pot would have a linear resistance curve human eyeballs don't act
like that at all and its doubtful that your LED would also have a linear
emission curve; its probably more logarithmic.

Check the datasheet for your LED and you should be able to calculate what 1K
of resistance would look like. If you can figure out its minimum operating
voltage, you could figure out a good pot value.

As for a diffusing cover, try a ping pong ball :)
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