At 01:04 AM 8/17/2004, Peter Moreton wrote:

>Don't forget that the piezo element can destroy a PIC pin if tapped
>sharply', the piezo crystal able to generate big voltages quite easily. For
>direct drive from a PIC pin, put a 10K res across the piezo pins to prevent
>this voltage generation.

there's another fun thing that happens, when you're using two pins to differential-drive.
You charge the capacitor (piezo), then take the low pin high, and you've just discharged a 10V capacitor into your protection diodes! (5v on the piezo, plus the 5V on the output pin.)

Not good.

If you take the high pin low, before taking the low pin high, then you're safe.

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