Evaluation circuit for electrical signals

US4363979A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Gunter Honig · Ditzingen, DE
• Joachim Braunger · Waiblingen, DE
• Imanuel Krauter · Munderkingen, DE
• Rainer Bone · Leinfelden, DE

Key dates

• Filing date: Nov 24, 1980
• Grant date: Dec 14, 1982
• Expiry date: Nov 24, 2000

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02P7/067
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

Signals from a coil producing pulses in response to flux variations produced by a rotary member driven by an engine crankshaft are applied in push-pull through series resistors to the inverting and non-inverting inputs of a comparator. A variable voltage divider for the input signals is provided by a pair of complementary transistors respectively connecting the comparator inputs to opposite poles of a fixed voltage supply. The comparator pulses charge a capacitor through a transistor, the capacitor being periodically discharged through a resistor, once per crankshaft revolution. An increase of capacitor voltage beyond a very small amount progressively lowers the resistances provided by the transistors connected to the comparator inputs, acting on one of them simply through a transistor and on the other through a transistor and a current mirror circuit. In order to compensate for the temperature dependent leakage current of the transistor driven by the comparator output in order to charge the capacitor, a second current mirror is provided that prevents charging of the capacitor during the blocked-condition of the transistor in question. A supplementary voltage divider is connected t…