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  1. #1
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    Information about a device

    Hello, I have bought a device that has an input, that connects to telephone line. The output is the input of the telephone line. This device samples the input and when there is sound on the input over 0,5Vpp, it waits, and when the sound leaves, it waits for 5 seconds, then it closes and opens a relais module. After that it sends 1kHz PWM, with adjustable duty cycle from a pot, for 5 sec in the output (so the previous output, when there is PWM, vanishes for 5 seconds). After that the output connects to the input and continues to output the signal of the input. Where this device could be used for? Do you have any idea?

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  2. #2
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    Re: Information about a device

    If you didn't know what it was, why did you buy it?



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  3. #3
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    Re: Information about a device

    It is probably a FAX diverting device - not used much these days and not much use for anything else.

    They 'listen' to the line for the FAX carrier tone, if it isn't there it diverts the call to a normal telephone, if the tone is present for long enough it assumes a fax machine is making the call and diverts the call to your fax machine instead. More modern machines had it built in to them.

    Brian.
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    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.


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  4. #4
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    Re: Information about a device

    Thank you.. and what is the purpose of PWM?



  5. #5
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    Re: Information about a device

    PWM doesn't travel well through a telephone line so I would guess the pot is just to minimize distortion. I would have to see the device to be sure.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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