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coin recognition!

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SimonTHK

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Hello electro tech online

I want to build a coin recognition system, I think that it works with something measuring the magneting field that can be let through the coin. I am not sure, but can anyone lead me in a direction of something that can measure resistance of a material without physical touch of the material?

I am on bare ground

thanks in advance
 
I used to work for a company that made coin (and bill) acceptors. As coins rolled down a ramp they passed by 3 coils that controlled oscillators. One free ran at 350 Khz, another at 450 Khz. The third was a air gap transformer the coin went through the air gap, I don't remember the frequency of that one but it was lower than the others. As the coin went past each coil it would pull the frequency of each oscillator. One measured diameter, The other measured thickness and the air gap measured metal density. A microcontroller monitered all 3 frequencys and used a 3 dimensional array to determine what the coin was.
 
Funny this came up. A few weeks ago I was visiting a friend who has too much time on his hands. He is into this thing with pennies (US Pennies). He ordered this gizmo from China (I think he needed to buy like 4 minimum) at about $7.50 USD each (not sure on price). These things are really slick. You place a coin that you want it to identify in the thing and it memorizes the coin. The thing has several outputs for whatever maybe counting? Anyway, you run pennies through it and it will distinguish between the old copper and new crap pennies. The thing also works for the old silver and new quarters. You shove a coin in and it learns the coin. I guess I could send him an email and ask for more info on the thing. I know they came direct from Cjhina, there was a minimum which really wasn't much as I recall and the things actually showed up all the way from China. I got a kick out of these little gizmos.

Ron
 
Ron, almost any of the modern coin acceptors will learn and signal via a parallel output what you have run through it, and the even better ones have an I2C style connector which gives even more information out. But your right china is great for buying these types of things. I run a few vending machines and have recently replaced a few of my validators, I think they were about £18 each, for cheapo ones, but they work well.
 
Ron, almost any of the modern coin acceptors will learn and signal via a parallel output what you have run through it, and the even better ones have an I2C style connector which gives even more information out. But your right china is great for buying these types of things. I run a few vending machines and have recently replaced a few of my validators, I think they were about £18 each, for cheapo ones, but they work well.

Yeah, it was funny because I am looking at this little gizmo whiz through pennies and he tells me it was $7.50 or so USD. It was just one of those things I never had any contact with or need to know about that left me thinking that little gizmo (OK coin validator) is really amusing for the buck.

Ron
 
I would love to get more info about the ones that I can buy, I dont have to build everything myself :) especially the I2C one since my project allready run I2C and it would be easy to implement.
 
I would love to get more info about the ones that I can buy, I dont have to build everything myself :) especially the I2C one since my project allready run I2C and it would be easy to implement.

I'll try to remember to email Steve and ask for more info from him.

Ron
 
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