blackie shared a project modding a Donkey Kong cabinet to take pennies, nickles and dimes on the Adafruit Forums:
I used a programmable coin acceptor, a trinket and relay to mod my Donkey Kong cab so it will take pennies, nickels and dimes.
The Adafruit Programmable Piggy Bank code only needed a few small changes….
Featured Adafruit Product!
Coin Acceptor – Programmable 4 Coin Type: Your project may be free-as-in-speech, but that doesn’t mean it has to be free-as-in-beer. This handy coin validator/acceptor module is just like the ones you’ve seen in arcades. This model has the cool ability to accept up to 4 different coins! For example, you can program it for 4 different US coins, or European, or Japanese OR you can have it accept 4 coins from different countries – say a Chinese Yuan, Japanese Yen, American Quarter and European Euro. First you’ll have to program it with what coins you want it to accept. Any coin from 15mm to 29mm in diameter can be used. Each coin is assigned a number of pulses, so for example, a nickel should be 1 pulse, a dime, 2 pulses, a quarter 5 pulses and a half dollar 10 pulses. When a valid coin is inserted, the output line will pulse for 20-60ms (configurable). The acceptor looks for diameter, thickness, dropping speed, etc to determine if a coin is valid. (read more)