dissipation limiter - switches transformer secondary

38 elektor electronics december 1985 In a stabilized power supply the dissipation in the stabilizer may become very high when the difference between input and output voltages is large. This phenomenon occurs particularly in stabilized mains supplies, and can be remedied by lowering the secondary voltage before the stabilizer. The suggested circuit here does this in a neat manner by making it possible to select either the full or half the secondary voltage. And that with only a few components! dissipation limiter switches transformer secondary Z. Pagkvan Figure 1. Switching from half-wave to full-wave rectification is effected by applying a suitable voltage to the base of T2. Figure 2. This diagram shows the effect on the voltage applied to the rectifier circuit when a base voltage, UB, is applied to T2. Figure 3. To get the full secondary output voltage, a voltage of 1...10 V must be applied to the base of T2. Rectifiers D1, D2, Th1, and Th2 are then connected in a bridge configur...