DescriptionKeeping track of coins can be annoying. I wanted to build a coin counter but had one key requirement, it had to run on batteries. I found a coin acceptor that makes the job easy, but it is power-hungry. Using capacitive sensing, we can turn on the acceptor module only when a hand is near, giving a 10-month stand by time.
This project was featured on element14 Presents.
Coin Acceptor
The coin acceptor from Adafruit can be programmed to detect up to 4 different coin types. They can any currency (maybe not even real coins.) You just need 15-20 of each coin type to train it. The program for each coin is programmable. In my case, I decided to detect US nickels, dimes, and quarters. The coin acceptor is set up to provide 1 pulse for the nickel, 2 for the dimes, and 5 for the quarters. This behavior means the pulses are each worth $0.05.10-month
Initially I wanted to keep track of each coin type, but the acceptor's output doesn't do anything to make that easy. Coins inserted back-to-back don't have any indication between coins.
So what is the challenge? The acceptor module runs on 12 volts and draws about 50 milliamps when idle. Inside is a solenoid that activates to drop the valid coins into the bank.
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