Circuit arrangement for detecting voltage differences

US3935524A · kind A · utility

Assignees

• Karl Vockenhuber · AT
• Raimund Hauser · AT

Inventors

• Heinrich Cap · St. Georgen, DE
• Herbert Krammer · Mödling, AT
• Robert Scheiber · Mödling, AT

Key dates

• Filing date: Sep 26, 1973
• Grant date: Jan 27, 1976
• Expiry date: Sep 26, 1993

Classification

• Technology area (CPC G): Physics
• CPC primary: G05D3/1472
• WIPO field: Control
• WIPO sector: Instruments

Abstract

An electronic switching system for the control of a load, such as a motor serving to adjust the diaphragm of a motion-picture camera, comprises a normally inactive comparison circuit including a transistor bridge with a pair of NPN transistors in one pair of adjoining arms and a pair of PNP transistors in the other pair. Two complementary transistors in each half of the bridge, lying between diagonally opposite corners, are provided with a common biasing circuit shunted across that bridge diagonal, the load being connected across the other bridge diagonal. Each biasing circuit includes a resistive voltage divider with taps joined to the bases of the associated bridge transistors and a group of cascaded ancillary transistors connected across a section of the voltage divider containing one of these taps. The first ancillary transistor of each cascaded group has its base connected to an associated input terminal receiving a switching signal and a reference voltage, respectively. A differential amplifier, connected across the input terminals, emits an unbalance signal which applies power to a pair of normally open-circuited ancillary transistors, forming part of the two cascaded groups…