Zenith Electronics Corporation

Mark A Scholten

Robert E Mudra

Stanley R Zachary

An audio power amplifier includes a stacked pair of complementary transistors having the emitters commonly coupled to a load. A driver stage couples the bases of the stacked pair to a source of audio frequency signal. A bootstrap capacitor is coupled between the commonly coupled output node and the supply voltage. An isolation diode is interposed between the bootstrap capacitor and the operating supply to prevent discharge of the bootstrap capacitor into the operating supply during positive signal swings.

Push-pull amplifier having bootstrap capacitor isolation

A television receiver includes a stereo amplifier having separate bass, treble and gain controls, for driving left and right channel loudspeakers. Separate bandpass circuits supply portions of the respective channel signals for phase inversion and feed back to respective summation circuits in the outputs of the corresponding opposite channel to produce an extended stereo effect. A switch simultaneously activates the syereo extender circuitry and operatively couples the bass and treble controls to the gain control for extending the frequency response characteristic and the volume level of the channels.

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Rolling Meadows, IL, United States of America

Mark A Scholten