The coin acceptor works by using sensors to identify the thickness, diameter, and fall time of the coins. It is easy to program, with the use of buttons and a 7-segment display on the side of the unit. You can select a coin profile, insert coin samples, and then designate the value. The coin acceptor then reads the serial output, telling you the value of each coin as they're inserted. The values are reported as binary bytes, with a selectable baud rate on the unit.
One of the standout features of the Sparkfun Coin Acceptor is its coin reject function. This allows your controller to tell the coin acceptor not to accept any more coins. Additionally, it has a loud alert beeper to notify you of any changes. To get the coin acceptor working, all you need is a pocket full of change, a 12VDC supply, and a place for the accepted coins to fall.
While you may not get rich building your own vending machines, the Sparkfun Coin Acceptor opens up a world of possibilities. It could be used for access control using different sizes of tokens, or even for a virtual vending machine where you can buy MMORPG items. The opportunities for coin-operated projects are endless.