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Trouble with LED button wiring
ShadeValryn:
I'm trying to use a 12V 500ma power supply to power 8 LED buttons (coin and start for 4 players). Splicing it and testing it seemed to work okay on the one button. I had some of these EZ Off harnesses from paradise arcade shop so I figured I'd give them a try too. I managed to get it working to where the light turns off when I press the button, but I'm a little unsure now where to put the ground wire that typically daisy chained from another button to this one. The post for the signal wire is open and I can see obviously where to connect that then go back to the iPac 4, but I was just unsure what to do now that the LED ground is now occupying that microswitch common ground post. Do I connect it to the ground that is daisy chained all the way down to the iPac 4? Do I daisy chain it somehow to the other LED buttons then back to the 12V power supply and just keep the signal wire seperate that goes to the ipac 4? Pictures below as to how my little test setup is. Any advice on where to put that ground? Does the signal wire require a ground return to the ipac4 or can it just have a ground from the 12v power supply?
PL1:
Here's one way to wire it so the LED turns off when the button is pushed. That is the effect you're going for, right?
The five red dots are the 5 QD terminals (2 LED socket + 3 microswitch)
NOTE: This won't work with an x-arcade encoder which uses a series of isolated commons (not tied to ground) or a ZD encoder. (active high device)
Using a ground from another source works with KADE, Xin-Mo, and Mini-Pac -- tested/confirmed by shorting to ground from a different USB cable or computer PSU frame.
You can use the ground from the LED lighting harness since "ground is ground."
It should also work with an IPac, Keywiz and any other active-low encoder that uses a real ground.
Scott
ShadeValryn:
So I can connect the ground back into the daisy chain of ground that goes back into the ipac no problem?
ShadeValryn:
Also, I just tested my sample with a multimeter and fond the bulb to be drawing 13.5v and 1.83A. The power supply is rated at 500mA, should I be concerned?
EDIT: I feel like an idiot, i was testing the amperage wrong. it's 1mA
PL1:
--- Quote from: ShadeValryn on October 26, 2014, 08:03:28 am ---So I can connect the ground back into the daisy chain of ground that goes back into the ipac no problem?
--- End quote ---
Electrons have a negative charge. They move from ground to positive.
Picture drinking through a straw
-- Ground is lilke a cup full of liquid and the straw is the circuit
-- When you suck on the straw, (apply a positive voltage) the liquid (electrons) flow through the straw (circuit)
-- If the straw is cut in the middle, you get an open circuit
The ground of the LED power supply will provide the few mA of electrons that the encoder draws -- no need to directly tie the LED supply ground and IPAC ground together.
If you don't believe me, short an encoder input to your PC power supply case and the encoder will output the corresponding keystroke. ;D
If something goes wrong with the LED supply ground wire and the LED daisy chain ground is directly tied to the IPac ground, the IPac ground will have to supply the current for both the LEDs and the encoder which could damage the encoder, depending on how much current the LEDs draw.
Instead of a big straw (LED power supply ground) and a little straw (IPac ground), the little straw would have to handle the full amount of liquid.
For the switches that you want to turn off when you press the buttons, wire them like the diagram above and use the ground from the LED power supply.
--- Quote from: ShadeValryn on October 26, 2014, 09:35:28 am ---Also, I just tested my sample with a multimeter and fond the bulb to be drawing 13.5v and 1.83A. The power supply is rated at 500mA, should I be concerned?
EDIT: I feel like an idiot, i was testing the amperage wrong. it's 1mA
--- End quote ---
1mA doesn't sound right at all -- should be closer to 20mA for 12v LEDs with a 12v supply. :o
Did you put your meter in series or parallel with the circuit to be measured?
Your amperage test setup must be in series (like below) so all the current has to flow through the meter. (all liquid through one measuring straw)
+V----red lead--multimeter--black lead----LED----ground
or
+V----LED----red lead--multimeter--black lead----ground
Any path around the meter like putting it in parallel (below) will give a false amperage reading because some current will flow through the meter and some will flow through the LED. (drinking through two straws, but only one measures how much liquid is going through it)
red lead--multimeter--black lead
| |
+V-----------------LED-------------------ground
Scott
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