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Electrical Wiring Question (Update: IT WORKS!!!!!)
Jdurg:
Okay, I'm a bit of a newbie with electrical wiring, but I do understand most of the basics. Therefore, I want to run this idea by some people before I implement it. Basically, I have a coin door with two distinctly separate coin-mechs and one coin meter that counts the coins put in. I want to hook up the coin mechs to two uniquely different inputs on my keyboard encoder, but have both of them increment the coin meter by one if a coin is put in. My problem was figuring out how to keep the two circuits independant from each other, yet have both of them be a part of the coin meter circuit. I think I can use diodes to accomplish this and place a diode on each circuit from the coin mech to prevent a signal from travelling in the wrong direction. A sketch of what I'm doing is below. Will this work? I'm using a 4.5V coin meter with a diode in it, and standard coin switches.
My apologies for the poor quality of the sketch. This was done with a touchpad and not a mouse. :cheers:
Ed_McCarron:
Looks like it'd work as long as both +5v are from the same source.
Also, it looks like the polarity of the diodes in your schematic might be backwards. If coin1 and coin2 are at +5v and go to ground when a coin is inserted, you want the positive from the coin meter to go thru the diodes to ground, right? When the coinx line is grounded, the anode will be at lower potential than the cathode in your pic, and no current will flow.
Of course, that observation is based on my high-tech education I received from Forrest Mims, so take with a grain of salt. Maybe someone else will verify.
Jdurg:
You know, I think I've figured it out. I just needed to write everything down on paper to see how all the circuits interact. Since electricty flows from the positive to the negative terminals, I'll have the +5V coming in to the coin meter. The negative line is connected to both the Coin 1 and Coin 2 NO terminals with a diode placed between the negative terminal on the meter and the NO connection on each coin mech. Therefore, when the coin mech switch is triggered by a coin moving through, the meter will have completed its circuit and the meter will increment by one.
At the same time, the coin switches work by having the positive signal from the keyboard encoder flow through the switch to ground thus completing the circuit. I'll connect the wire from the encoder to the NO position on the appropriate switch and put a diode between the two terminals to direct the flow towards the switch only. I think that by doing this on both switches I'll prevent any current flow in a direction I don't want, and thus keep both circuits independant, yet linked to the meter. Any time either switch is pressed, the meter will be able to complete it's circuit thus incrementing by one, and the encoder will complete its circuit thus allowing MAME to recognize an inserted coin! Sweet. I think I've got it. I just need to work on the diode types to make sure I don't hurt any of my components.
Jdurg:
--- Quote from: Ed_McCarron on March 23, 2008, 02:04:51 pm ---Looks like it'd work as long as both +5v are from the same source.
Also, it looks like the polarity of the diodes in your schematic might be backwards. If coin1 and coin2 are at +5v and go to ground when a coin is inserted, you want the positive from the coin meter to go thru the diodes to ground, right? When the coinx line is grounded, the anode will be at lower potential than the cathode in your pic, and no current will flow.
Of course, that observation is based on my high-tech education I received from Forrest Mims, so take with a grain of salt. Maybe someone else will verify.
--- End quote ---
Yeah. I noticed that soon after drawing it up. After thinking outloud for a while and drawing it down on paper, I think I've figured out how this will work.
Jdurg:
Okay. I think I've now updated the schematic to one that will work. I just wonder if it's overkill having the diodes on the switch-to-encoder line?
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