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Coin sensor

Discussion in 'Hobby Electronics' started by Harry Pfeifer, Oct 14, 2006.

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  1. I am working on a microcontroller based project, which is to be coin
    operated, but do not yet have a working coin collection system.

    I have a quantity of devices described as "coin sensors" which came as
    freebies along with some other wanted components which I bought some time
    ago. They consist of three flat coils mounted side by side, with two slots
    in between, where coins could be passed through. The two outside coils are
    wired in series, but the centre coil is a separate circuit. I tried
    connecting one coil circuit to a signal generator and the other to a CRO to
    see what response they gave when a coin was passed through them. There was a
    response, but it was not consistent, and did not adequately distinguish
    between coins of different values, or steel washers, whereas the
    commercially available coin receivers costing several hundred dollars, and
    which appear to operate on a similar principle,are able to distinguish
    between coins of different values

    Could someone please give me information on how they achieve this, or
    alternatively, how the coin sensors which I have, are intended to be

  2. n Sat, 14 Oct 2006 00:52:45 GMT, "Harry Pfeifer"
    Can you take a photo of it and post it to a website somewhere?
    Typically there are 2 main types of coin validators. One is an
    electronic unit that measures metallic content and then either sets an
    output high or sends a serial message. These can be single
    denomination or multi denomination. The latter being far larger in

    The other type is a single denom coin comparator. These measure the
    metallic content of a reference coin then compare it to the coin
    traveling through the slot. They are typically analogue devices that
    from memory run from 24VAC. Most will divert the coin to another chute
    if it does not match, with the actual coin count being handled by a
    photointeruptor. In fact, there is usually 2 sets of optics that can
    also detect coins going in the wrong direction in case some is trying
    the ol coin 'YO-YO'!
  3. Mark Harriss

    Mark Harriss Guest

    Old Telstra yellow payphones used weight to accurately detect coins,
    this was good enough to determine if a coin was Australian or Kiwi
    as the identical sized Kiwi coins were of a different weight but
    identical size and most likely to end up in a coin slot. I forget
    if they had different diameter chutes for the coins to be sized in
    before weighing but they passed extensive testing using slugs, washers
  4. jasen

    jasen Guest

    easiest way is to buy one, Microsystems Corp. makes a good product.
    it sounds like he could place a good coin in one of the slots and then
    feed one of the coils with a reference signal [maybe a 1Khz square wave?]
    and look for a null on the other coil when another coin of the same type
    passes through the other gate,

  5. True this is, but did the OP not ask about an existing unit?

    You have no idea, perhaps its time you stopped pretending to be a
    genius by reading the internet and focused on shit you actually know
    something about.
  6. R1rob

    R1rob Guest

    Ebay. Pinball machine section. Can usually be had cheap.

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