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Talking Clock

Discussion in 'Electronic Design' started by w, Oct 1, 2003.

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  1. w

    w Guest

    Hi all

    Iam after a circuit diagram for a talking clock.

    Most apreciated if anyone can help.

    Jay Mather
  2. Frank Buss

    Frank Buss Guest

    Currently I'm using a PIC 18F252 for another project. It has 32 kB
    Flash memory. Assuming you need 15 seconds pre-recorded voice,
    it should fit into the Flash, if compressed with ADPCM, which is easy to
    decompress for the PIC. The datasheet:

    The circuit diagram would be the 18F252, a crystal oscillator, a battery
    with voltage regulator (but you can use the 18LF252, which works from
    2 V to 5.5 V; I don't now, if the crystal oscillator likes it) and
    some push-buttons only, if you don't need a display. But there are
    displays out there, which can be driven by digital output from the PIC
    without any additional components.
  3. Frank Buss

    Frank Buss Guest

    I forgot the digital to analog converter. Could be a R2R network:

    and perhaps a standard amplifier for the loud speaker.

    Another idea: perhaps you can use the PWN output from the PIC (amplified by
    a transistor) to drive the loud speaker.
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