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Electrical Wiring Question (Update: IT WORKS!!!!!)
Jdurg:
In my updated drawing, the +5V would be coming from the power supply. The GND/Coin1/Coin2 wires would all be going into the IPAC/Keywiz which would get their power from the connection to the computer.
--- Quote from: Ed_McCarron on March 24, 2008, 03:35:36 pm ---
--- Quote from: DaOld Man on March 24, 2008, 10:06:12 am ---You should be concerned with how much current the counter draws.
I would be afraid that it would be too much for the Ipac.
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Wha?
In Jdurg's schematic #2 way up there, the IPAC input sits at 5v, most likely via a pull up resistor. The (-) side of the counter will be at 5v when idle, so no current at all will flow.
When the switch is triggered, both will be pulled to ground. No current will flow from the ipac other than what would normally flow when you ground it's input.
Unless i'm missing something (which is very possible) the optoisolators seem like overkill - unless you are worried about the inductive kick from the coil field in the counter collapsing - which can be handled by the reverse biased diode shown later.
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Jdurg:
--- Quote from: DaOld Man on March 24, 2008, 03:28:37 pm ---Actually the formula to find amps is watts/volts
So
2 watts / 4.5 volts =0.44 amps (or 440 MA)
Or if you use a 5vdc power supply:
2 watts / 5 volts =0.40 amps or 400 ma
The second drawing, using the opto isolators to trigger the encoder inputs should work very well.
I would not switch the counter with the opto isolators like I show in my first drawing. it may overload the optos.
The coin switches should be good for at least a couple of amps.
You will need to use 1 amp diodes.
also the resistors for the opto isolators need to be around 200 ohms, not 330 as I originally posted.
If you do something to reduce the current, you will reduce the voltage too.
If you get much below the 4.5 volt rating, you may harm the counter, or it may not work properly.
With the currents you are looking at, i dont think i would feed the ground or the pos for the counter through the encoder.
But if you go with your first drawing, you will need to tie the ground of the power supply with the ground of the encoder, since the coin switches are breaking the ground.
Good luck, and keep us posted..
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Thanks for the help. This is something that I should be able to test out using my older meter first to ensure that it will work with my new meter. I'll also be able to test it when I finish building my CP over the next month or two and can hook it up to my coin door and to my desktop computer.
However, in looking at my second drawing, the diodes being used to control the flow of electricity from my encoder to my switches should prevent any large voltages or current from going to my encoder. I'm guessing that your concern is with voltage flowing through the ground wire and creating issues there? If that's the case, shouldn't i be able to just ground the coin switches to the gnd line on the power supply yet still have them register on the encoder?
DaOld Man:
You can try that.
if the encoder ground is the same as the power supply ground, that should work.
(You can use an ohm meter to check that.)
If they are not connected somewhere already, then you will need to put both power supply and encoder grounds on the common of the coin switches.
I would not use the ground from the encoder to power the counter.
The current will be the same from the power supply ground, through the coin switch, through the counter and back to the power supply positive.
You want to insure that the counter current cant feed through the encoder ground.
Jdurg:
Problem solved. The KeyWiz keyboard encoder has a +5V output on it that can be connected to the coin meter for the +5V, and the the use of some simple diodes to direct the flow of electricity will keep things working. Since the +5V is coming from the encoder, I am certain that there will be no issues. I can then use the power supply of the computer to light the coin-door LEDs and the trackball's LED. ;D
Jdurg:
Small update here. The CP is built and the wiring to the coin-door is ready to start. (For testing purposes). I recalled that the USB port can provide 5.0 volts at 500mA which is just above the ~440 mA that the counter will require. As the KeyWiz I bought connects through PS/2 (which also requires +5V and works with a USB Adapter therefore taking advantage of 500 mA), I am VERY confident that the amperage going through the KeyWiz from USB will not harm it. Plus, hacking a USB cable to power the meter will be pretty easy to do and make for a quick connection in the base of my cab.
Tomorrow I hope to pick up the diodes I'll need to direct the electrons in the right direction and will fire up Gauntlet to see if it works out alright. I was going to use the +5V connection on my KeyWiz, but I can not see how anybody could solder a wire on there without destroying the encoder. WAAAAAAAAAAAAY too small for someone like me to do anything.
Once the wiring is complete, I'll let everybody know how it turned out.