Keuffel & Esser Company

James R Trummer

An AC coupled amplifier system is protected from overloading input signals by means of a 'bootstrap' circuit which provides a compensation signal substantially matching the overscale portion of such input signal and applies that compensation signal to the coupling capacitor as an offset in order to prevent excessive charge accumulation on that capacitor. A voltage controlled current source serves as a signal range limiter in the circuit and responds to overscale input signals by causing a circuit loop opening and forcing loop closure in a secondary feedback circuit from which the extent of input signal overscale is determined. The matching compensation signal is then derived from such determination. The protection circuit further provides a reset function to account for extended overscale input signal levels.

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Tullahoma, TN, United States of America

James R Trummer