2 Batteries vs 3 Batteries

by nitrodude150 on Fri Aug 03, 2012 6:10 pm

SO I just finished building 4 SpokePovs today, and they're all going to be mounted on one wheel and cleverly programmed so I can have two colors. What I noticed, however, is that my 2 green boards use 3 batteries and are VERY Bright, as opposed to my 2 Pink Boards which only have 2 batteries and are nowhere near as bright. I'm using the same fully charged 1.2V enelopes throughout the boards.

My question is, can I add a third battery to the Pink Boards and achieve a brighter effect without ruining anything? The resistor networks I have on the purple board are rated at 56Ohm

Thanks! :mrgreen:
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Re: 2 Batteries vs 3 Batteries

by adafruit_support_bill on Sat Aug 04, 2012 7:22 am

Pink? I don't believe we stock pink SpokePOVs. Green and Blue leds have a higher forward voltage than red & yellow, so they need three batteries for the higher voltage. What controls the brightness is the current. The resistor networks supplied with the kits are designed to produce a bright light without overloading the leds. If you use different leds, you should calculate the resistor size accordingly http://www.ladyada.net/learn/arduino/LEDs.html.

Another thing that will affect the apparent brightness of the leds is that human vision is most sensitive in the yellow-green portion of the spectrum. So, all else being equal, green leds will naturally appear brighter. If your pink leds are already being driven at the maximum safe current, you may need to dim down the green leds with a higher resistance value.
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