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Driving a small (20w) audio amp from a pic output, best way for clear low-mid freq alarm sound?

Discussion in 'Electronic Basics' started by Me, Apr 24, 2007.

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  1. Me

    Me Guest

    Hi all,
    I'm making a kitchen countdown timer ( my first pic project ) for the wife,
    who is half deaf and needs a low to mid range frequancy alarm with some UMPH.

    Q1. What's the best way to couple a pic output pin to a 20 watt amp?
    Q2. Will the amp try to draw too much current from the pin?
    Q3. Should I use a transistor switch ( or pair ) to drive the amp?
    Q4. Would a line driver be better than an amp?

    I need to keep the internal temperature down as low as posible as it's
    going in the kitchen.

    Thanks for any help.
  2. 20watts is a pretty big amplifier for this sort of thing.

    If she hears that badly, you might try something like flashing a light,
    instead. Or a vibrator, though that's not really a suitable solution
    here since you'd need the vibrator to be in contact with her, so you'd
    need to move to some wireless solution.

  3. If it is a normal audio amplifier with a line in jack, a 100
    k volume control with one end grounded, and one connected to
    the PIC output with a .1 uF or larger cap, wiper to
    amplifier input.
    Not if it is a line input. If you are also building the
    amp, then it depends on what you build.
    I think the PIC should be able to drive it.
    The amp has to be able to drive the speaker that will
    produce the sound. An ordinary audio amplifier should work
    If you build the amp, it can be one with a saturated output
    (full square wave) not a linear hi fidelity type. This will
    make the amp sound harsh, like a siren, but will make it run
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