| 摘要 |
The invention relates to a piezoelectric, acoustic alarm, comprising a resonance cavity (1), in which piezoelectric elements (2a, 2b), each excited by a square wave voltage are arranged opposite each other and oscillate in opposing directions. The two square wave voltages (Va, Vb) which are controlled by a microprocessor (8) are phase-shifted by a rectangular wave pulse length and are positive or negative. A piezoelectric alarm, configured and excited in this manner is characterised by a high sound level with a low voltage consumption and a reduced size.
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