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Electrical help re: common earth
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rCadeGaming:
+1 with everything above.  Just be sure you understand the ATX pinout and what you're connecting.

Also, it won't hurt to add extra ground connections between components just be safe.  In audio/video connections this is usually helpful to reduce hum from potential differences.  Just be sure you're connecting to a common ground point on each component.

EDIT:  Just saw you latest post while typing this.  Whatever button connection you're using on the I-PAC, your coin mech needs to connect it to ground to indicate a coin, NOT voltage.  No connection = button not pressed, connection to ground = button pressed.

EDIT 2:  Can't keep up.  As long as the computer rail is providing enough current (amps) you can probably power the LED's through the IPAC or directly from the PC, whichever you prefer.  You might want to place a resistor in series with the LED to restrict the current flowing through to only what's needed to light it up.  Otherwise, it's nearly a straight connection to ground, and other things like the I-PAC may lose power.  I don't know if the I-PAC's LED connection is regulated for this, but it shouldn't hurt anything to add a resistor and be safe.  When calculating resistor size, keep in mind the forward voltage drop through the resistor.
EightBySix:
Hmm, still a bit of confusion - the LEDs are a bit of a red herring here.

My 'coin-o-matic' in the link above (there is a vid, a few images down) sets a high signal when a coin is detected (just happens to light an LED so I could test it). Sounds like i need it to pull the line low instead to connect to the iPac.

So as long as the grounds are connected, they can each have their own voltage?
mcseforsale:
OK.  Sorry, I didn't see the link.  Can you program the PIC to send the correct number of pulses out to a lead on the iPac (to the coin1)?

AJ
rCadeGaming:

--- Quote from: EightBySix on November 13, 2012, 12:11:52 pm ---My 'coin-o-matic' in the link above (there is a vid, a few images down) sets a high signal when a coin is detected (just happens to light an LED so I could test it). Sounds like i need it to pull the line low instead to connect to the iPac.
--- End quote ---

Exactly, and there will be voltage coming out on the iPac's button wire, so make sure that's not feeding into your circuit; it should just go straight to ground.


--- Quote from: EightBySix on November 13, 2012, 12:11:52 pm ---So as long as the grounds are connected, they can each have their own voltage?
--- End quote ---

Yes.  The voltage in the two should be completely isolated from each other.
EightBySix:

--- Quote from: mcseforsale on November 13, 2012, 12:19:13 pm ---Can you program the PIC to send the correct number of pulses out to a lead on the iPac (to the coin1)?
--- End quote ---

Yep - thats how I wanted it to work. Put a pound in and you get 10 goes, or 5p + 2p +2p + 1p = 1 credit. You get the idea  ;D

Thought it would be a good place for all the spare change in my pocket, and teaches the kids maths too ;-) When they get older, I'll set it to - say - 1 credit = 8p to help them with their times tables. Muahahaha.


--- Quote from: rCadeGaming on November 13, 2012, 12:19:47 pm ---Yes.  The voltage in the two should be completely isolated from each other.

--- End quote ---

Cool. thanks everyone.  :cheers:
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