Circuit to make a telephone bell ring

Discussion in 'The Projects Forum' started by jamesday, May 3, 2015.

  1. jamesday

    Thread Starter New Member

    May 3, 2015
    Hi i am after a simple circuit that i can build or buy to make an old telephone bell ring. I need it to work from 12dc, so therefore a converter circuit that will convert 12dc to 50ac,

    if anyone has any ideas or help it would be greatly appreciated. Thanks in advance
  2. Art

    Distinguished Member

    Sep 10, 2007
    Is the ring voltage not 90 Volts where you are? It is here.
    It’s something like a 25 Hz (could be wrong there) sine with narrow peaks.
    I have done it with PWM cycling through values till I found a working frequency.
    from the PWM pin, a FET switching the 12 Volt supply on one side of a transformer might do it.

    you will need to push pull true AC to get the solenoid to strike the bell on either side of the solenoid in the phone.
  3. jamesday

    Thread Starter New Member

    May 3, 2015
    hi i live in the uk, and it states the ac voltage of the phone line is 50v ac but can be anthing up to 120ac i think so 90v will be ok :) would you have a circuit diagram to follow? - as im fairly new at this but know the basics of circuitry. thanks james. also thanks for replying
  4. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    the uk phone ringer is 50V dc pulsed at 25hz to 40 hz, at 0.4second on .2 second off, repeated twice then a 2 second break, you can make one with a 555 timer and psu, if you have a masterbox on your phone the line is on pins 2,5 with the ringer circuit on pins 3,5 the high voltage will be from the back emf of the bell coils.
    Last edited: May 3, 2015