the output delivered by a transducer having an integral power law transfer characteristic is stabilized by controlling output signal components related to the operating bias and gain of the transducer circuit . a test input signal comprising a sine - wave is applied to the transducer . the fundamental and integral harmonic components are filtered from the resulting output signal . the transducer is stabilized by restoring in sequence the amplitude of the harmonic and fundamental components to predetermined values respectively related to desired operating gain and bias conditions . a typical transducer is a cathode ray tube .