Replacing Coin acceptor to with Opto interrupter to initiate action

Discussion in 'General Electronics Chat' started by medicare, Apr 19, 2016.

  1. medicare

    Thread Starter New Member

    Apr 19, 2016
    Replacing Coin acceptor to with Opto interrupter to initiate action
    Dear sir

    I am in the business of Coin Operated height Weight BMI Machine.

    I have some electronic issue Please Help.

    I have a motherboard for such machine which uses coin acceptor using 12 V supply.

    I wish to change it to a coin acceptor that only uses a photo Interrupter which uses 5 V

    Please let me how to proceed.

    Should you need more information just let me know.
    upload_2016-4-19_14-52-17.jpeg upload_2016-4-19_14-52-17.jpeg


    Mr Ramputty


    the mother board of my coin operated weight height measurement machine is operated by inserting in a coin acceptor GD 315 model which uses 12 v
    i want to use same mother board in another old machine which is operated by inserting a coin in in coin accepter using opto inrrupter which uses 5 volt.
  2. hp1729

    Well-Known Member

    Nov 23, 2015
    ??? GD315 is RS232 or USB??? 3 size coin acceptance?
    You want to add the optic at the output of the GD315? As long as you can set it up for single coin acceptance that might work. Does the GD315 require a signal from the system to enable and disable it?
    I think we need more info on the GD315 and your mother board before we can get specific. But I think your answer will be, "no".
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Take your 12V power source and add a 5 V regulator to concert to 5V for your new board. Is that all you need? Or is there more to the story?

    Google "LM7805 datasheet" for more info.
  4. dl324

    AAC Fanatic!

    Mar 30, 2015
    Are you concerned about counterfeit coins? Specs say GD315 accepts three coin sizes. Presumably, it has a way to detect counterfeits. An interrupter can't weigh coins.
  5. Tonyr1084

    Well-Known Member

    Sep 24, 2015
    I'll have to make several assumptions here but if you don't care what is dropped down the coin slot then using the interrupter will work.

    I assume the GD315 is programmable to accept and count various coins and discriminate between coins and slugs, when a preset value has been reached (and this is a big assumption) IF the 315 sends a high signal to the mother board (or - MB) then your weight scale will operate (as controlled by the MB), displaying a weight.

    IF you use an interrupter then depending on how you wire it, it too can send a high signal to the MB, triggering it to display weight.

    The interrupter is just an LED and a photo transistor. When the beam is on the transistor is on. When the beam is broken the transistor toggles off. So using that as a pull down you should be able to trigger the MB.

    Of course this is a lot of assumption on my part. And using the proper resistances you should be able to use the interrupter on the original 12 volts, no need to drop the voltage down to 5V.
  6. Tonyr1084

    Well-Known Member

    Sep 24, 2015
    Here's my thinking: Replace the GD315 with the interrupter. 12 volts is supplied to the LED via R1. The LED beam strikes the photo-transistor (PT) (or photo-diode) turning it on and taking the high signal to ground. The high signal is provided via R2. As long as the beam is not interrupted the PT remains on holding the high signal at ground. When the beam is interrupted the PT opens the ground and allows a high signal to travel to the high input (12 volts via R2) to the MB.

    Remember, this is all under the assumption that the GD315 sends a high signal to the MB when the correct change has been entered. IF the MB talks back to the GD315 with instructions on how much change to return - you're going to have to figure something else out.
  7. medicare

    Thread Starter New Member

    Apr 19, 2016
  8. medicare

    Thread Starter New Member

    Apr 19, 2016
    Thank you for your reply
    You seems to have understood my problem.However there is a catch here.
    the main board is initiated when a positive signal is sent that if i short circuit the signal wire with ground the machine get initiated ok.The main board is operated at 12 v -the signal volatge or current Ampere I do not know!

    The opto interrupter operated at 5 volt and the current is 25 mA The emitter send signal continuously to the detector and .when a coin is thrush in it stop right! so they are operated in opposite direction.

    in the first case input 1 output is 1 and input 0 output 0
    in case of opto interrupter it is input 1 output 0 and input 0 output is 1
    hope i made my point

    second issue is the output current generated by the opto circuit is not enough to initiate the mother board so i need to increase the output i suppose.How do i do that
  9. Tonyr1084

    Well-Known Member

    Sep 24, 2015
    In my drawing I held the "High Signal" low by pulling down the line voltage through R2. I gave no values for any of the resistors because it's something that must be set to be compatible with what you're working with. If you need a heavier current you can use the interrupter to drive the base of another transistor. If you need a high signal when a coin passes then you set it up to be pulled low as long as the beam is uninterrupted. But if you need the opposite then you set it up with a "Pull-up" circuit, one with a transistor that can deliver the amperage you need.

    I can't imagine the mother board needing a very high current signal, but I'm not in possession of your machine so I can't test it out. AND I'm not the expert here. There are many more who have a much better grasp of things than me. And when it comes to the math and engineering of this sort of stuff - it takes me a long time to work through the numbers. In the long run I can usually achieve my goal, but often with a little bit of smoke leakage along with a few blown out components because I missed something between conversion between KΩ and mA.

    I wanted to offer an idea that might spur you on to think of even better ways of accomplishing the task. I have no experience with Arduino but I bet that could be set up to do the job without all the fancy pull up or pull down circuits - or whatever may be needed.

    I wish you well in figuring out a solution to the problem. I'm sure you will get there one way or another. And there's never any shame in asking for help.

    Peace. (yes, I'm an old fella)

    I'm assuming in the case of the GD315 an input of 1 (digital high signal) the output is 1. In the case of the interrupter, it's input is high (1) until the beam is broken. Suggesting to me that the transistor turns on when the beam is broken. I don't think I've encountered a device like that before - but again, I'm not the most experienced man here. Still, I suppose that could be the case. If so then when the beam is blocked you get a high output. If that's what's needed by the MB then you don't need the pull-up resistor in my circuit (R2). Again, I'd need hands on to understand the requirements better.

    I'll keep watching. If I have any other ideas, especially if I can get a better grasp on what it is you're working with, I'll be happy to include any comments (or drawings if that makes things clearer).

    Last edited: Apr 21, 2016
  10. medicare

    Thread Starter New Member

    Apr 19, 2016
    i have been able to connect the Photo interrupter and make the mother board work perfectly well .
    now i have a new issue to discuss.
    when i power the motherboard (12 v) and the opto interrupter sense (5 V) separately using two separate power supply the unit work perfectly well.
    However if i use a regulated power supply having two output of 5v and 12 v - the unit does not work..
    Please advise how to solve this problem.
    I would rather use one power supply unit rather than two separate power supply>
  11. cmartinez

    AAC Fanatic!

    Jan 17, 2007
    Check i your separate power supply has a common ground for both sources. You may have to tie those two grounds together in case they are separated.