I got a problem where pulse voltage from acceptor is about 20mV. How can I solve my problem? and I can't detect the pulse using arduino uno. please any one can help ?

  • Output seems kind of low... Are you powering it with +12 volts? – BobT Sep 8 '16 at 16:34
  • yes I power it with +12v adapter and 1 A , it is a big problem to me since that this module doesn't exist in my country , and I wait 1 month to got it .Is their any solution? – محمود عبد الكريم Sep 8 '16 at 18:37
  • I don't know- it just seems odd that the output voltage is 20mv. I think you've either miswired it or you have a defective unit. Check the documentation to see what output voltage you should expect. – BobT Sep 8 '16 at 21:11
  • I'm now trying to amplify this value to 5V Is this right ? or I must buy another one ? – محمود عبد الكريم Sep 9 '16 at 6:43

From this Amazon review:

There are 'live' (12V), 'ground' and 'signal' wires coming out of the back. Live and ground are pretty self-explanatory, and need to be connected to a 12V supply - I bought a simple 1A DC one. The final wire says 'signal', and needs to be connected to your circuit as input into a GPIO pin in the case of a raspberry pi. It produces a pulsing 5V signal (Why not tell us it will be 5V somewhere in the documentation? Luckily I have a multimeter) as a way of encoding which type of coin it has encountered. However, raspberry pi's only want 3.3V signals as inputs, so you'll be wanting to make a voltage divider (With a couple of resistors - I used 33k and 18k) to safely bring that 5V pulse down to 3.3V. (http://en.wikipedia.org/wiki/Voltage_divider) You'll also want to connect the ground from the device to a ground on your Raspberry Pi, or the signal won't work. I did this by splicing the ground cable from the power supply so that it has 2 ends - 1 for the power supply to the unit, and one for the unit to the Raspberry Pi Circuit.

It seems that a 5v pulse is the expected output. How are you measuring the output? You'll need a 'scope rather than a multimeter measuring voltage...

Anyway, I would not try to 'amplify' the signal, I would look to check the connections are correct and if that's not the issue, I would return the unit as defective.

  • 1
    I wonder if the output is actually an "open collector" type that needs a pull up resistor to 5V before you see a proper pulse. Pull-ups can be configured on the AVR input pins - which the Amazon reviewer may have done on his GPIO pin - or an external resistor could be used. Regards, – Michael Vincent Sep 9 '16 at 11:32
  • good point @Michael Vincent +1 – KennetRunner Sep 9 '16 at 11:36
  • I connected the signal to an arduino and programmed the unit just like the videos in YouTube, the arduino cant read the signal, then I tried to detect the signal using oscilloscope, I spent 1 week on trying many solutions all of them failed, then the last thing I'm going to do is to amplify the value to 5 V, I'm wondering if their is any possible solution ! – محمود عبد الكريم Sep 9 '16 at 20:46
  • what do you mean with "scope" You'll need a 'scope rather than a multimeter measuring voltage... ? – محمود عبد الكريم Sep 9 '16 at 20:47
  • and the big problem is that this unit isn't available in my country and I waited about one month to get it form outside!! and bringing anther one will be time consuming . – محمود عبد الكريم Sep 9 '16 at 20:51

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