Back in my days in the coin-op business, we wrote code that watched the length of that coin input pulse. Too short or too long - it got rejected. It eliminated

Back in my days in the coin-op business, we wrote code that watched the length of that coin input pulse. Too short or too long - it got rejected. It eliminated a lot of the abuse cases with coins on strings, people kicking the coin acceptors to move the microswitch, etc.