[Noisebridge-discuss] Electronics Question

[Jake]

phil,

did you try swapping the "output" pins of the optocoupler?  It is a 
photodiode in there (not a relay) so it does care about polarity i think.

it seems like you are being properly methodical, keep it up and you will 
succeed.

Your calculation of 33 ohms for the LED side of the optoisolator is 
probably fine, although 100 ohms would probably work just as well.  You 
are supplying 5V from the arduino, to an LED (maybe infrared in there) 
which takes maybe 1.8 volts, at 0.020 amp.  so 5v - 1.8v = 3.2v, and a 
resistor making 0.020 amps at 3.2v is 3.2 / 0.020 = 160 ohms.  Just my 
guess without looking at the datasheep.

what are you trying to make?

-jake