Control circuit for single-phase variable amplitude oscillator - uses long tailed pair differential amplifier to regulate switching of push=pull transistor pair in DC=AC inverter

摘要

The circuit is intended for an oscillator supplied from a DC source and using a push-pull oscillator, and includes a differential amplifier (16) controlled by an oscillator (10) and supplied from a current source (18). An astable circuit (15) is inserted between the differential amplifier (16) and the Q,Q bar inputs of the push pull circuit (12) so that variations in the supply voltage (2) do not affect the oscillator output voltage. The differential amplifier (16) comprises two transistors (T1A, T1B) connected in parallel between the astable crcut and the current generator (18) in a long tailed pair configuration with the current generator (18) in the tal. The emitter circuit of the differential pair (16) incorporates a potentiometer (P1) to adjust the symmetry of the output wave.