Security alarm system

Abstract

Abstract A SECURITY SYSTEM, INCLUDING A VOLTAGE DIVIDER HAVING A FIRST IMPEDANCE MEANS INSIDE THE PROTECTED AREA AND A SECOND IMPEDANCE MEANS OUTSIDE THE PROTECTED AREA, THE IMPEDANCE MEANS BEING SEPARATED BY A TAP POINT. ALSO INCLUDED IS A TRANSISTOR AMPLIFIER HAVING A VOLTAGE STABILIZED INPUT, AND RESISTOR COUPLING MEANS INTERCONNECTED BETWEEN THE VOLTAGE DIVIDER TAP POINT AND THE VOLTAGE STABILIZED TRANSISTOR AMPLIFIER INPUT. THE FIRST IMPEDANCE MEANS LOCATED IN THE PROTECTED AREA INCLUDES A PAIR OF RESISTORS ALTERNATIVELY CONNECTABLE IN SERIES WITH THE SECOND IMPEDANCE MEANS LOCATED OUTSIDE THE PROTECTED AREA. ONLY ONE OF THE ALTERNATIVELY CONNECTABLE RESISTORS OF THE FIRST IMPEDANCE MEANS IS VARIABLE IN RESPONSE TO AN ALARM CONDITION IN THE PROTECTED AREA, ENABLING THE SYSTEM TO BE SELECTIVELY DISABLED. A THIRD IMPEDANCE MEANS, WHICH IS SELECTIVELY SHUNTABLE, IS INTERCONNECTED BETWEEN THE TAP POINT AND THE FIRST IMPEDANCE MEANS. THE ALTERNATIVELY CONNECTABLE RESISTORS OF THE FIRST IMPEDANCE MEANS ARE UNEQUAL IN VALUE AND RELATED TO THE THIRD IMPEDANCE MEANS IN A MANNER SUCH THAT THE SUM OF THE RESISTANCE BETWEEN THE DIVIDER TAP POINT AND THE SIDE OF THE FIRST IMPEDANCE MEANS REMOTE FROM THE TAP POINT IS CONSTANT REGARDLESS OF WHICH OF THE RESISTORS OF THE FIRST IMPEDANCE MEANS IS CONNECTED IN SERIES WITH THE SECOND IMPEDANCE MEANS, THEREBY PREVENTING THE SYSTEM FROM BEING DEFEATED BY RESISTOR SUBSTITUTION.

Inventors

• 👤 Donald E Hansen

Bibliographic Details