Glass breakage detector - uses piezoelectric break noise sensor coupled to detector circuit with protection against false triggering

摘要

The detector system provides improved sensitivity without increasing the susceptibility to false triggering by stray signals. The sensing system consists of piezoelectric devices that are triggered by breaking noises. A light emitting diode (8) is used as an indicator. Outputs from the detector stages are fed to an amplifier (2) and latching stage (3) that avoids responding to false signals. The stages are supplied by a constant current circuit (4) fed from the mains (9). An output (10,11) generated is fed to an alarm device.