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Telephone ring and caller end hangup detector

  1. Jan 11, 2010 #1
    I need a telephone to answer when called, dial a number on another telephone, and then hang up when the caller hangs up. I have both the pick up issue and the dial issue solved. The mail problem is the hanging up after the caller hangs up. I'd be very happy if I did not have to use a programmable microcontroller, but if I have to then I will.

    Original Plan:
    For the answer part of the circuit I have a ready made ring detector that goes out to a spst relay. That will be used to send a signal to a latched relay. The latched relay will connect the phone to the line. For the Dialing part, I am going to just limit the signal going to the latched relay and send that to transistors going to switches (I already have several phones ripped apart). As for the hanging up part, it is a little more complex. Since the telephone line puts out 0 volts when the caller hangs up, I was going to make a NOT gate and send the line signal through that. Lastly, the signal will also be sent to the latched relay.

    Do you think this will work?
    Do you have a better idea?
    I would also like to get some of your ideas.
    I need this project to be done soon so please help me ASAP.

    MISC Facts and measurements:
    telephone on hook voltage~60v DC
    telephone off hook voltage~7v DC
    telephone ring voltage~120v AC

    Thanks in advance,


    Attached Files:

  2. jcsd
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