Hi there!
I'm also trying to do this, but with multiple coins. I've run into a lot of trouble with getting it to actually work, and was wondering if you got this to work and could help me out. First, I'm not really sure what to do with the 'counter' wire. Also, I'm having trouble telling the arduino how to differentiate between the coins based on the pulses. Any help would be greatly appreciated. Thanks!
-Rex