I posted in the other thread too about this. The comparitive coin mech Ultimarc supplies works fine using the 5.5v zenerdiode to change the coin signal from the native 12v down to the i-pac friendly 5v. As Andy says, the i-pac just senses regular 5v microswitch-type presses, which is fine for a single-denomination, switch-type coin mech. If your coin door/mech uses an electronic credit board (as most commercial-use mechs are designed to), it's a little trickier as the output signal is not quite the same - delivering the signal in relay pulses depending on the coin amount inserted.