IMPEDANCE ALARM SYSTEM
Patent
·
OSTI ID:4182111
A description is given of electric protective systems and burglar alarm systems of the capacitance type in which the approach of an intruder at a place to be protected varies the capacitance in an electric circuit and the change is thereafter communicated to a remote point to actuate an alarm. According to the invention, an astable transitor multi-vibrator has the amplitude at its output voltage controlled by a change in the sensing capacitance. The sensing capacitance is effectively connected between collector and base of one stage of the multivibrator circuit through the detector-to-monitor line. The output of the detector is a small d-c voltage across the detector-to-monitor line. This d- c voltage is amplified and monitored at the other end of the line, where an appropriate alarm is actuated if a sudden change in the voltage occurs. The present system has a high degree of sensitivity and is very difficult to defeat by known techniques.
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-14-006496
- Assignee:
- U.S. Atomic Energy Commission
- Patent Number(s):
- US 2907017
- OSTI ID:
- 4182111
- Country of Publication:
- United States
- Language:
- English
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