Figure 5.3, Simple Voltage Regulator Circuit. A transformer is shown on the left. Its primary is not shown connected to any source of AC. Obviously this is necessary for proper function. The secondary of the transformer is connected to a bridge rectifier. From now on bridge rectifiers will not be described in detail. One of the AC inputs goes to the anode and cathode of D1 and D2. The other AC input connects to the anode and cathode of D3 and D4. The connection at the cathodes of D2 and D4 is the positive output. The connection to the anodes of D1 and D3 is the negative output. The preceding four sentences will not be repeated in future descriptions. 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 R3 to the top of a pot, R4. The bottom of R4 connects through R5 to common. Common is the negative output terminal. The positive of C1 connects to one end of a resistor, R1. The other end of R1 connects to the base of Q1. The base of Q1 also connects to the collector of Q2, another N P N transistor. The base of Q2 connects to the wiper of R4. The emitter of Q2 connects to the cathode of zener diode D5. The anode connects to common. A resistor R2 connects between the positive end of C1 and the cathode of D5. End verbal description.