Kajcsa Laszlo wrote:
>
>  Anybody knows how to do a circuit witch beeping in a piezo buzzer(a
>little one; like in the watches and games)?
>

You can simply drive the buzzer directly off of a PIC pin, without
need for other circuitry. However, you may want a 100 to 1000 ohm
resistor in series with the piezo to control volume and prevent
overdriving.

Simply send a square wave out the PIC pin. Piezos are supposed "tuned"
for specific frequencies, but will actually give usable output from
100 to about 5000 hz.

If the square wave doesn't sound good enough to you, you can
add some RC-filtering or a more complicated circuit to round
the corners of the pulses.

- danM

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