how to detect coin mech pulses


I'd really appreciate some advice on a project that I'm right in the middle of. I hope I've posted in the right section - I've searched the rest o the forum but I still don't really understand how to tackle my problem.

I'm trying to get a coin-mech (the type used in arcade machines) to work with the arduino. it is a single coin type that allows the pulse to be set manually.

The wiring harness for the mech is as follows:

grey line: counter (+/-) red line: DC +12V White line: Coin Signal Black Line GND grey Line: counter (+/-)

The spec sheet for the mech states that the timer Switch, for synchronising the system has three options: 100ms 50ms 30ms

OK.. from what I understand i would need to use the White Line to ascertain when a correct coin has been inserted - counting the pulses, I believe..

Firstly, I haven't been able to work this out. Secondly, I think I blew one of the pins by putting the line straight into my arduino - how do I avoid this?

Many thanks for any advice!

Did you connect all the ground lines together (mech+Arduino)?

What voltage do you measure on the white line with a multimeter?

Hi Fungus,

I haven't tied all the ground lines together should I do so?

The Voltage from the coin line is 6v


Yes all grounds need to be connected together.

If the coin mech gives 6V output, then you need a voltage divider to drop it to 5V. Try a white-1Kohm-5kohm-gnd circuit and use arduino to sense between the two resistors. What are grey counter +/-?