Coin button wiring for freeplay and coin slot

[stigzler]

I'm building an arcade cab. This has one coin slot (which functions as a button) and two freeplay buttons for Coin 1 and Coin 2. These go into an arcade controller board (for coin 1 and 2). What I'm wanting is for Coin 1 + 2 buttons to fire individually (so if P1 presses coin 1, only coin 1 gets fired on the controller board) and same for P2. However, if a coin is put into the coin slot, then both Coin 1 and 2 are fired (as only have one coin slot!). My initial setup attached, but this, of course, triggers both coin 1 and 2 on the controller board for all buttons. I'm thinking I'm likely needing to use a diode, but know nothing about them. Could anyone advise, please?

[PL1]

I'm building an arcade cab. This has one coin slot (which functions as a button) and two freeplay buttons for Coin 1 and Coin 2. These go into an arcade controller board (for coin 1 and 2). What I'm wanting is for Coin 1 + 2 buttons to fire individually (so if P1 presses coin 1, only coin 1 gets fired on the controller board) and same for P2. However, if a coin is put into the coin slot, then both Coin 1 and 2 are fired (as only have one coin slot!). My initial setup attached, but this, of course, triggers both coin 1 and 2 on the controller board for all buttons. I'm thinking I'm likely needing to use a diode, but know nothing about them. Could anyone advise, please?

Here's the setup you need for 3 buttons + 2 blocking diodes ==> 2 inputs with an active-low encoder.
- Diagram was originally for Upper Flipper/Magnasave with a MAME/VPin setup.
- No pinball tables use both Upper Flippers and Magnasave so this setup allows you to trigger both inputs with one flipper button in VP while still using the inputs separately for MAME.
- Any 5v diode will work.  The 1N4001 is common and inexpensive.   



The inputs (Left-Ctrl and A) have pullup resistors that keep the input at 5v (logic high) until ground is applied to the input.
- That 5v is applied to the anode (no-band end) of both diodes, but there is no ground on the cathode (band end) so the diodes are not forward biased and do not conduct.

When you close the middle switch (Left Upper/Magnasave), ground is applied to the cathode of both diodes ==> the diodes are both forward biased so they conduct and ground is applied to both inputs. (Left-Ctrl and A)

When you close the top switch (P1B1), ground is applied to the top input (Left-Ctrl) and to the anode of the top diode.
- Ground on anode ==> top diode is not forward biased so it does not conduct, blocking the ground from reaching the cathode of the bottom diode.

When you close the bottom switch (P2B1), ground is applied to the bottom input (A) and to the anode of the bottom diode.
- Ground on anode ==> bottom diode is not forward biased so it does not conduct, blocking the ground from reaching the cathode of the top diode.

For an active high encoder like the "zero delay" encoders, inputs are at logic low, replace ground with 5v in the diagram and reverse the diodes so the cathode is toward the input.

If you don't know which type of encoder you have, connect your multimeter black probe to ground and red probe to one of the button tabs.
- If the multimeter shows logic low (near 0v) when you press the button, it is an active low device.
- If it shows logic high (near 5v) when you press the button, it is an active high device.


Scott
EDIT: Forgot to mention that you don't need diodes if your two single-input buttons have 3-tab microswitches.