Push-Pull Oscillators

Author: J.B. Hoag

A push-pull oscillator circuit is shown in Fig. 14 K.

Fig. 14 K. A push-pull oscillator

When a random voltage fluctuation makes the grid of tube 1 positive, it makes the grid of tube 2 negative. These cause changes in the plate current. Resonated by the inductance and capacitance (the tank) in the plate circuit, they cause voltage changes on the plate which, fed through the plate to grid capacitance (or by magnetic coupling between the two tank circuits), reverse the polarity of the grids.

This continues, the tank circuits strengthening the voltage changes of the grids and plates, so that strong oscillations are developed. In addition to the fact that the two tubes are operating to give greater power, the symmetry of the circuit makes it particularly suitable for use at ultra-high frequencies.