BURGLAR DETERRENT TIMING SWITCH

• Main Authors: STETTNER J,US, OTT J,US
• Format: Patent
• Language: English
• Published: 25.09.1973
• Subjects: ALARM SYSTEMS; ORDER TELEGRAPHS; PHYSICS; SIGNALLING; SIGNALLING OR CALLING SYSTEMS

A burglar deterrent switch for installation in a conventional manual switch box for controlling room lights. An electronic sound responsive timing switch illuminates the room lights for a selected period of time in response to the occurrence of a sound and then turns the lights off for another selected period of time. The timing switch has a triac which is shunted across the manual light switch. The gate of the triac is controlled by an SCR connected in a bridge rectifier for controlling the triac gate current. The gate of the SCR is connected to the output of an amplifier and is switched on by sound incident upon a sound transducer connected to the input of the amplifier. A timing circuit means is also connected across the SCR and comprises a pair of voltage reference diodes connected parallel to a capacitance for fixing the voltage to which the capacitance may charge and having a resistance series connected to the parallel diodes and capacitance.