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Title: IMPEDANCE ALARM SYSTEM

Abstract

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.

Inventors:
Issue Date:
OSTI Identifier:
4182111
Patent Number(s):
2907017
Assignee:
U.S. Atomic Energy Commission
Patent Classifications (CPCs):
G - PHYSICS G08 - SIGNALLING G08B - SIGNALLING OR CALLING SYSTEMS
NSA Number:
NSA-14-006496
Resource Type:
Patent
Resource Relation:
Other Information: Orig. Receipt Date: 31-DEC-60
Country of Publication:
United States
Language:
English
Subject:
ENGINEERING AND EQUIPMENT; ALARM SYSTEMS; AMPLIFIERS; CABLES; CAPACITORS; CIRCUITS; CONTROL SYSTEMS; CURRENTS; ELECTRIC POTENTIAL; ELECTRONICS; MULTIVIBRATORS; OSCILLATIONS; SENSITIVITY; TRANSISTORS; VARIATIONS

Citation Formats

Cowen, R G. IMPEDANCE ALARM SYSTEM. United States: N. p., 1959. Web.
Cowen, R G. IMPEDANCE ALARM SYSTEM. United States.
Cowen, R G. Tue . "IMPEDANCE ALARM SYSTEM". United States.
@article{osti_4182111,
title = {IMPEDANCE ALARM SYSTEM},
author = {Cowen, R G},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1959},
month = {9}
}