| 摘要 |
An alarm device, suitable for use with venetian blinds and other retractable blinds and curtains, comprises, secured together as as single unit, a piezoelectric motion sensor (9), an amplifier circuit (7) electrically connected to the piezoelectric sensor to amplify signals generated in the sensor, an audible alarm (8) electrically connected to the amplifier circuit for activation by the amplified signals, and a source of electrical power (10) for the circuit and the audible alarm. In one embodiment described, the unit is built upon a printed circuit board (6) and is of such shape and dimensions as to fit in the bottom rail (4) of a venetian blind.
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