Figure 6.14 Regulated Power Supply. At the left a transformer is connected to a bridge rectifier which in turn is connected to C1 in the manner we saw repeatedly in chapter 5. The negative of C1 is at the bottom and the positive of C1 is at the top. Positive goes to the drain of an F E T, Q2. The source goes through R1 to the cathode of a zener diode, D5. The anode of D5 goes to negative. The cathode of the zener also connects to the gate of Q2. The cathode of the zener also goes to the noninverting input of an op amp. The negative power input goes to the negative line. The positive power input goes to the positive line. The output of the op amp goes to the base of a transistor, Q1. It is drawn with the collector above the emitter rather than with the collector to the left of the emitter which is usual in power supply schematics. The emitter connects to the positive output terminal of the supply. The positive output terminal connects to one end of R2. The other end of R2 connects to the top of a pot, R3, and the bottom of R3 goes to negative through R4. Negative connects to the negative output terminal. The wiper of the pot goes to the inverting input of the op amp. End verbal description.
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