Hi. Here's a noob question for you
I have one circuit with a power source (batteries) powering an led, controlled by a switch.
I want this same switch (single pole) to also set an arduino pin HIGH when it is pressed.
Can I use a transistor? From what I've been reading here - http://www.ermicro.com/blog/?p=423
I should be able to use something like a 2n3904 transistor to switch the arduino pin high when there is a current in the other circuit, but I cant work it out.
Am I going about this the right way? And do both circuits need to be powered from the same power source for this to work?