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How to build an alarm like in a clock ?

Discussion in 'Electronic Design' started by kash, Jul 10, 2003.

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  1. kash

    kash Guest

    Is there information how the alarms in alarm clocks work. I know the use
    a piezzo devise for the sound, but what circuit or IC do they normally use
    to generate the signal?
    Thanks in advance
  2. Ian Stirling

    Ian Stirling Guest

    The unhelpfull and true answer is a clock IC, which is sometimes
    a 4 bit microcontroller with special ROM programming.

    Do you want to generate an alarm tone?
  3. kash

    kash Guest

    The unhelpfull and true answer is a clock IC, which is sometimes
    You know the 4 short beeps most digital alarm clocks make? this is what
    I was thinking. If there is some IC that will do it without to many
    complications, that will do for me.
  4. kash

    kash Guest

    There are a few solutions, what sort of skills and equipment do you
    I can buy any components I need from maplin/cpc (UK). Perhaps there
    is a chip that would play a little tune, that should be fine as well.
  5. If you can find it, there's the old SAB600 from siemens.
    Plays 'ding-dang-dong' and sounds very nice. Once used
    for doorbels etc.

    Example at:
  6. kash

    kash Guest

    Coudn't find it on maplin or fanell (uk), mind you will it work with a piezo?
  7. Rich Grise

    Rich Grise Guest

    You could do it with a couple of 555s, (or a 556), a 4-bit binary
    counter, and some gating logic. And yes, this can be made to drive
    a piezo, and in fact, there are special piezos made that serve both
    the function of the frequency-determining (feedback) element AND the
    audio output transducer. They use one transistor and one resistor.
    But you'd still have to generate and gate the pulses that turn the
    beeper on.

    Or you could get a beeping Sonalert, for about fifty bucks. =:-O

    Good Luck!
  8. kash

    kash Guest

    I am not sure what exactly you mean to be honest, can you draw
    up some circuit.
    Maybe, I know nothing about piezos except that I really like there sound
    much better than a speaker. Mind you, when I say that I am not too
    bothered about the quality of the beeps this is not entirely true. I would
    very much like to have this special sound quality which alarm clocks
    have, as I am used to it, and because it sounds professional. Any idea
    how this sound is generated?
    No, idea what this would be, though the price is ridiculous - out of
    the question.
  9. kash

    kash Guest

    Actually, I though of this idea, I may try it
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