Figure 5.5, Improved Voltage Regulator Circuit. A transformer is shown on the left. The top of the secondary goes to the top AC connection on the bridge. The bottom of the secondary goes to the bottom AC connection. The negative output goes to common. The positive connects to the positive of C1. The negative of C1 goes to common. The positive of C1 goes to the collector of an N P N transistor, Q1. The emitter of Q1 goes to the positive output terminal of the power supply. The positive output terminal connects through R2 to the top of a pot, R3. The bottom of R3 connects through R4 to common. Common is the negative output terminal. The positive of C1 connects to the collector of Q2, another N P N transistor. The emitter of Q2 connects to the base of Q1. The base of Q2 connects to the output of an operational amplifier. The inverting input goes to the wiper of R2. The positive voltage supply for the op amp goes to the positive of C1. The negative voltage supply goes to common. The voltage supplies should not be confused with the inverting and noninverting signal inputs. The positive of C1 goes to the drain of an F E T, Q3. The source of the fet goes to one end of R1. The other end of R1 goes to the cathode of zener diode D5. The junction of R1 and D5 connects to the gate of the fet. The junction of R1 and D5 also connects to the noninverting input of the op amp. End verbal description.