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Author Topic: How to connect a 12v coin counter?  (Read 8764 times)

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Kman-Sweden

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How to connect a 12v coin counter?
« on: December 14, 2009, 02:55:00 pm »
I have the two coin mechs connected to my I-Pac4.
I've tried to connect the counter to the ground so that both coin mechs would trigger a count but there doesn't seem to be enough power in the singal to turn the counter.
It's labeled 12v and does work. I've tried it with the 12v I have going to the lightbulbs on the coin eject buttons. I just hoped that the 12v was maximum dc not actual working dc.
With the counter connected mame does not even register the key press. Any bright ideas out there?



HaRuMaN

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Re: How to connect a 12v coin counter?
« Reply #1 on: December 14, 2009, 03:15:21 pm »
Have you tried hitting it?

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #2 on: December 14, 2009, 03:48:09 pm »
No. And I wouldn't catalog that as a "bright" idea.  :angry:

HaRuMaN

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Re: How to connect a 12v coin counter?
« Reply #3 on: December 14, 2009, 03:51:03 pm »
 ;D

Franco B

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Re: How to connect a 12v coin counter?
« Reply #4 on: December 14, 2009, 04:24:13 pm »
I think they do need 12v to function.

I just wired up a coin counter to my Neo Geo Naomi cab. The coin counter is connected to the credit board which runs off 12v.

You would have thought that feeding the your counter 12v would have moved it though. Have you tried giving it 12v pulses (on,off,on,off) as I imagine that will be how they work.

If you like I could try manually feeding mine 12v in that way, at least we know if your mech is working or not then.

We would still need to find a way of getting the coin counter working with your I-Pac. I'm only guessing here but maybe some kind of 12v relay? I.e when the coin mech micro is triggered it activates a relay to give a 12v pulse to the coin counter?

It may not be as 'simple' as that (or there is probably some super simple answer!  ;D) I'm just thinking aloud here.


Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #5 on: December 14, 2009, 04:32:21 pm »
It does turn on 12v. As I tried to explain I tested this off the 12v to the lights and it worked, so the counter isn't broken or anything like that.
12v out from the I-Pac would be awesome. A relay is a simpler answer than trying to place another switch in the coin mech. I'll have to look into that some more.  :cheers:

Franco B

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Re: How to connect a 12v coin counter?
« Reply #6 on: December 14, 2009, 04:51:59 pm »
Ah crap, I completely read your post as doesn't rather than does

At least it does work then  ;D

I'm just guessing at the relay idea, my electronics knowledge isn't the best but it looks like you may have more of an idea of if its feasible.

Let us know how you get on.  :cheers:

Franco B

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Re: How to connect a 12v coin counter?
« Reply #7 on: December 14, 2009, 04:56:26 pm »
I just had a little dig and found [this] thread with these two answers which may help.

Q:
I've got a coin counter I want to wire. How do I wire to both coin slots at once?

A:

You will either need some diodes or an OR chip, I believe.

Good luck.



A:
I believe it can be done with just diodes but you run the risk of running too much current through your encoder.  The safest way is with diodes and transistors.  I have set this up before (I had relays powering the counter but that is overkill...the circuit is basically the same though).  If no-one else posts a schematic, I can draw one up this weekend.

Hopwfully whammoed or someone may see this thread. If not maybe you could drop him a PM.

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Re: How to connect a 12v coin counter?
« Reply #8 on: December 14, 2009, 05:51:29 pm »
This thread may be of some help too. I used relays to help isolate them and to send a hard ground as well.

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #9 on: December 15, 2009, 03:10:29 am »
Thanks for all the help guys.
I'm still not sure if I understand the schematics but relay sounds easier, right?
12v in to the relay and a weaker signal (ie button pressed/coin dropped) closes the circut and lets the 12v pass through the counter..

That way the 12v is, in a way, isolated and can't acceidently fry my I-pac4, right?

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Re: How to connect a 12v coin counter?
« Reply #10 on: December 15, 2009, 10:50:21 am »
That's what a relay does!  Think of it as an electronic switch.  Instead of mechanically pushing a button which closes a switch, you are using an electric signal to do the work.

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #11 on: December 15, 2009, 01:45:16 pm »
So I dug out my Digital Multimeter and measured 2,2v over a button.
This means I have to find a relay that has about 2,5V "over the coil" and can stand 12vdc passing through it, right?
Is that all I need? No diodes and crap like that? I see some of you have them on some schemes.
Help me out here Electro-Wizards.  :cheers:

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Re: How to connect a 12v coin counter?
« Reply #12 on: December 15, 2009, 07:22:24 pm »
Isn't this the perfect application for a CMOS inverter? A small voltage through 1 input pin triggers another voltage at another input pin something like this?



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Re: How to connect a 12v coin counter?
« Reply #13 on: December 15, 2009, 08:38:04 pm »
The amount of current available from the pull-up resistor on the input board (which is what provides that voltage you see when the switch is open) is generally pretty minuscule, on the order of 1-3mA.  That's not enough to drive a relay coil.

Fortunately, there's no need for a relay, here.  Grab yourself a couple of diodes (1N400x or 1N4148/1N914, both available at radio shack, will work).  Counter red wire to 12V, black wire to anode (non-striped) end of one diode.  Wire from the input device (e.g. keyboard encoder) goes to anode of the other diode.  Both cathodes go to one side of the switch, and the other side of the switch goes to ground.  When the switch is on, it'll pull the encoder input low and energize the counter.  All the current flows through the switch.  The encoder doesn't see any of it.

Note that the input device will probably need TTL threshold inputs for this to work due to the voltage drop across the diode.  Most devices do have TTL level thresholds.

whammoed

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Re: How to connect a 12v coin counter?
« Reply #14 on: December 15, 2009, 10:53:21 pm »
The amount of current available from the pull-up resistor on the input board (which is what provides that voltage you see when the switch is open) is generally pretty minuscule, on the order of 1-3mA.  That's not enough to drive a relay coil.

Fortunately, there's no need for a relay, here.  Grab yourself a couple of diodes (1N400x or 1N4148/1N914, both available at radio shack, will work).  Counter red wire to 12V, black wire to anode (non-striped) end of one diode.  Wire from the input device (e.g. keyboard encoder) goes to anode of the other diode.  Both cathodes go to one side of the switch, and the other side of the switch goes to ground.  When the switch is on, it'll pull the encoder input low and energize the counter.  All the current flows through the switch.  The encoder doesn't see any of it.

Note that the input device will probably need TTL threshold inputs for this to work due to the voltage drop across the diode.  Most devices do have TTL level thresholds.

If doing it this way it should be noted not to use the encoder as the ground point.  The meter can use up to 5 watts (maybe more for older style meters) and the usb port is only rated to handle 2.5 watts.  This is where "running the current through the encoder" comes from since most people tie the grounds to a terminal on the encoder. 

MonMotha

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Re: How to connect a 12v coin counter?
« Reply #15 on: December 16, 2009, 12:46:56 am »
Eh, the ground line on a USB cable can transiently handle the extra current.  Remember that it's 5W @ 12V, not 5V/Vbus, so only 410mA, which is actually within the spec for the current carrying that ground line, though it's added with whatever you're actually drawing from Vbus.  Best to run it directly back to a ground line on the PC if you can, though.  Presumably you can find a good, solid ground return from the same place you're pulling 12V.

The 500mA current limit (note that you're only allowed to draw >100mA from USB if you "ask" and are approved by the host) is totally arbitrary.  They do size the wires to handle just about that much but over much longer distances than you're dealing with, and it'll just cause some voltage drop.  Many USB hosts (especially older ones) will actually let you draw quite a bit more :)

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #16 on: December 16, 2009, 01:07:29 am »
Thanks MonMotha! After drawing a picture for my self I got your explanation. Many thanks.
The issue that Whammoed pointed out about grounding will not be a problem since I have 12v and ground running to the lights of the coin buttons from the computers PSU. I'll just daisy-chain from there. I'll swing by a electronics shop and ask about those diodes on the way home from work..
Since I have two coin buttons but one counter I need 3 diodes, right? One between each button and the encoder and one between the counter and the two buttons?
Cheers!

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #17 on: December 16, 2009, 01:28:21 am »

MonMotha

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Re: How to connect a 12v coin counter?
« Reply #18 on: December 16, 2009, 01:44:25 am »
Actually, you need 4 diodes.  The counter hooks up to the anode of both, then the cathodes hook up to each coin switch individually.  The encoder inputs hook up as you describe.

Since I don't know the current spec on your counter, I'd go with the 1N400x series (a 1N4001 will work fine, but any 1N400x will work) as they have a much higher current rating than the 1N4148 type.

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #19 on: December 16, 2009, 07:25:48 am »
So I can't do like this?


Crap Iphone camera..  :angry:

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Re: How to connect a 12v coin counter?
« Reply #20 on: December 16, 2009, 07:51:04 am »
So I can't do like this?


Crap Iphone camera..  :angry:

no, coin switch one will also trigger coin switch two and vice versa.  follow the current flow.

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #21 on: December 16, 2009, 08:00:19 am »
Bloody hell... You're right.  :notworthy:

whammoed

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Re: How to connect a 12v coin counter?
« Reply #22 on: December 16, 2009, 11:58:10 am »
Eh, the ground line on a USB cable can transiently handle the extra current.  Remember that it's 5W @ 12V, not 5V/Vbus, so only 410mA, which is actually within the spec for the current carrying that ground line, though it's added with whatever you're actually drawing from Vbus.  Best to run it directly back to a ground line on the PC if you can, though.  Presumably you can find a good, solid ground return from the same place you're pulling 12V.

The 500mA current limit (note that you're only allowed to draw >100mA from USB if you "ask" and are approved by the host) is totally arbitrary.  They do size the wires to handle just about that much but over much longer distances than you're dealing with, and it'll just cause some voltage drop.  Many USB hosts (especially older ones) will actually let you draw quite a bit more :)

I believe it.  Just taking the better safe than sorry approach.  ;)

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Re: How to connect a 12v coin counter?
« Reply #23 on: December 16, 2009, 12:05:15 pm »
I believe it.  Just taking the better safe than sorry approach.  ;)

Fully recommended.  I'm all for doing things "the right way".  Just not probably something to worry about too much in this particular case.

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Re: How to connect a 12v coin counter?
« Reply #24 on: December 18, 2009, 05:49:10 am »
It didn't work.  :banghead:
The counter turned over nicely but no coin was detected by Mame.
I grounded it directly to the PSU and when that didn't work I tried the ground on the I-Pac to no avail.
The counter turned with both grounds but no coin where added in Mame. I have to do some more investigations this weekend.

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Re: How to connect a 12v coin counter?
« Reply #25 on: December 18, 2009, 09:33:53 am »
Open up notepad and try it.  Since it is a keyboard encoder you should get the characters to show up in notepad.  This will tell you whether to look at the setup of your circuit or mame configuration.

MonMotha

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Re: How to connect a 12v coin counter?
« Reply #26 on: December 18, 2009, 06:17:25 pm »
On the off-chance that this is a problem, try using 1N4148 style diodes for the lines coming from the encoder but 1N400x diodes for the lines coming from the counter.  1N4148 has a lower Vf and better recovery characteristics.

Kman-Sweden

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Re: How to connect a 12v coin counter?
« Reply #27 on: December 20, 2009, 03:59:16 pm »
Okey. First issue was that NO and NC on the coin mech switch was inverted compared to "normal" button switches.
Got that sorted and got one coin to register with the counter connected... One... After that nothing.  :banghead:
Every coin was counted but mame didn't add coins.

The counter isn't labeled with + and/or - could that be it? 
I might be running it the wrong way?
Maybe the relay isn't that bad of an idea after all?

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Re: How to connect a 12v coin counter?
« Reply #28 on: December 22, 2009, 09:40:39 am »
Okey. First issue was that NO and NC on the coin mech switch was inverted compared to "normal" button switches.

That, and the decimal point, will get you everytime.

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Re: How to connect a 12v coin counter?
« Reply #29 on: December 23, 2009, 05:57:27 pm »
See Ken Layton's post regarding installation of a freewheeling diode around your counter.  The diode should "point" the opposite direction of current flow when the counter is engaged.  That is, the anode should be on the side opposite the supply, and the cathode should be on the side connected to the supply.

From an electrical point of view, there's not much difference between a relay and an electromechanical counter.  Both use a coil to generate a magnetic field and make something physically happen.

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Re: How to connect a 12v coin counter?
« Reply #30 on: December 24, 2009, 05:35:14 am »
Thanks. I'll give it a go next week.
So the point would be to "drain" the coils from any stored power? Could this stored power have a negative effect on the button signal?

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Re: How to connect a 12v coin counter?
« Reply #31 on: December 26, 2009, 09:28:59 am »
When the power is turned off to a relay, the magnetism in the coil begins to collapse.
This collapsing magnetic field cuts through the wires of the coil, generating electricity.
Think of it as striking a bell, the bell vibrates for quite some time after striking.
The voltage in the coil builds up to a point that can be hundreds or even thousands of volts.
Solid state equipment (transistors, etc) dont like a voltage that is a lot higher than it was designed for. Even though the voltage created by the coil only lasts a few milliseconds, it can be long enough to destroy the device.
A relay or switch contact is not as prone to this high voltage (called Counter Electromotive Force or CEMF), however it can produce arcing between the contacts, which wear away at the contact's surfaces.
A diode placed across the coil "shorts out" the current in one direction.
This effectively keeps the CEMF very low, because the CEMF is alternating current, and since the diode is shorting it in one direction,  the CEMF voltage never has time to build up very high.
The current is very low, so the diode is not damaged.
Think of a diode as a piece of wood placed against the bell right after striking the bell.

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Re: How to connect a 12v coin counter?
« Reply #32 on: March 01, 2010, 07:46:32 pm »
OK, I finally got around to setting up this coin counter circuit using just diodes.
I used a GP-wiz gamepad control interface and a typical 12v coin counter.

Results: the circuit worked as it should...until it didn't.  
The good:  The switch triggered an input on the gamepad and caused the coin counter to increment by one.
The bad:  Inevitably at some point on each test the GP-wiz would freeze up and no longer show inputs or have frozen input(s).  The only rememdy to get the GP-wiz working again was to unplug the usb cable and plug back in.
The better:  I originally thought my coin counter had an internal diode for back emf.  It did not.  I added a diode "across the coil" of the counter and now the circuit works great with no GP-wiz freakout.
The Lesson:  If using this circuit make sure you use a diode for back emf.

I also set this up using a transistor to "fire" the counter.  This worked flawlessly even without a diode across the coil of the counter but one still should be used.

***edited post after fixing circuit with back emf diode
« Last Edit: March 01, 2010, 08:14:24 pm by whammoed »

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Re: How to connect a 12v coin counter?
« Reply #33 on: March 04, 2010, 06:16:33 am »
Post some :pics maybe?

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Re: How to connect a 12v coin counter?
« Reply #34 on: January 16, 2017, 04:17:05 pm »
OK, I finally got around to setting up this coin counter circuit using just diodes.
I used a GP-wiz gamepad control interface and a typical 12v coin counter.

Results: the circuit worked as it should...until it didn't. 
The good:  The switch triggered an input on the gamepad and caused the coin counter to increment by one.
The bad:  Inevitably at some point on each test the GP-wiz would freeze up and no longer show inputs or have frozen input(s).  The only rememdy to get the GP-wiz working again was to unplug the usb cable and plug back in.
The better:  I originally thought my coin counter had an internal diode for back emf.  It did not.  I added a diode "across the coil" of the counter and now the circuit works great with no GP-wiz freakout.
The Lesson:  If using this circuit make sure you use a diode for back emf.

I also set this up using a transistor to "fire" the counter.  This worked flawlessly even without a diode across the coil of the counter but one still should be used.

***edited post after fixing circuit with back emf diode

Please expand on how you accomplished this
Thank you
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Re: How to connect a 12v coin counter?
« Reply #35 on: January 21, 2017, 04:21:53 pm »
This thread has been most helpful  :cheers:
I would just like to share my experience with hooking up a 12v Coin Meter to my I-Pac

I was so paranoid about destroy my I-Pac with 12v  :o

I wired my coin meter up to the I-Pac and so-far so-good, nothing has been fried or failed to work. The coins are being registered on the coin meter and the I-Pac is awarding credits properly. No issues  :D
The I-Pac (with the help of the diodes) are seeing none of the 12v I thought it would be.

I tried separating the ground wires (to limit 12v grounding through the I-Pac and thus the USB port)
1. Coin Meter would ground to the PSU
2. Coin from the I-Pac would also ground to the PSU (by-passing the I-Pac altogether)
Didn't work for me, I-Pac would not register the credit switch.
My thinking being, was the credit switch was still completing a circuit. (Still some things I have yet to understand  :dunno )

So wired the whole lot up as per the picture = working!  :applaud:
(The diodes are under the heatshrink, sorry, should have taken the pictures 'before' finishing the connection)

One more thing, that diode across the Coin Meter, install one! Do it! Even if you don't have an I-Pac, it'll save your JAMMA board (or whatever you have it plugged into)
I was just testing the coin meter by tapping the connection on to 12v.  Coin Meter would work and count one, but not without a bright spark!  :o
After wiring in that diode, no spark! Beautiful!
The diodes are you friends  ;D