PIEZO-HORN DRIVING CIRCUIT

摘要

A circuit is disclosed for driving a piezo ceramic device as used in smoke alarms or other audio warning devices. The circuit detects the resonant frequency of the piezo horn and provides an alternating current at the resonant frequency of the horn for maximum sound output. The circuit has a self starting resonant oscillation characteristic. Two pairs of switches act in concert to alternatingly connect each side of the piezo horn to the supply voltage and ground, causing the maximum voltage swing across the piezo horn to be effectively twice the available power supply voltage.