If you need a real loud
beeper, this circuit delivers about 110db (12 inches away) from a 9v battery using
a single inexpensive C-MOS IC. An off-the-shelf piezoelectric beeping device is
driven at resonance to insure maximum efficiency. By changing the control IC to a
74AC14, the same circuit can operate from 3v and 1.5v batteries.
Published in Electronic Design, Aug 5, 1993
Click on Drawing Below to view PDF version of Schematic