Self-balancing magnetic amplifiers of the differential-feedback type

This paper is concerned with the application of differential-feedback circuitry to push-pull self-balancing magnetic amplifiers in order to obtain extreme stability and freedom from zero drift with a minimum of core matching and component selection. It describes a 60-cycle magnetic instrument amplifier particularly well suited for extending the range of application of a standard-type moving-coil ink recorder and gives the results of various measurements and actual performance characteristics. This amplifier acts as an operational amplifier and is suitable for various applications in instrumentation, telemetering, automatic control, and analog-computer technique.