Operating glass breakage alarm installation - using voltage provided by piezo element in response to mechanical vibration to provide alternating magnetic field

摘要

The alarm device uses at least one piezo element (1) responding to the mechanical vibrations resulting from glass breakage to provide a corresponding AC voltage. The latter is fed directly to an oscillation circuit (2) for providing a magnetic alternating field which can be coupled to a second oscillation circuit (8) to provide a voltage for operating the alarm. Pref. an inductive coupling (4, 6, 7) is provided between the oscillation circuits, the signal from the second oscillation circuit being fed to the alarm via an amplifier (10). ADVANTAGE - Eliminates need for auxiliary energy source.