Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
The figure shows a full-wave rectifying circuit. The input signal, which is sinusoidal, is applied to the transformer T. The transformer secondary is center tapped so that the signals from the secondary are out of phase. The positive-going signal on line 1 drives transistor Q1 which works as an emitter follower having an emitter resistor Re. The negative-going signal from the other half of the transformer is supplied on line 2 to the base of transistor Q2. Then negative going signal turns transistor Q2 off. When the signal polarity changes, Q1 and Q2 reverse roles. The transistor Q3 is used as a diode. The current and therefore the voltage drop across Q3 is set by the resistor R. The voltage drop is used to bias Q1 and Q2 and compensate their base/ emitter drop. This, therefore, creates a quiescent output level of zero.