How to Build a Bipolar Power supply for Battery instruments . A bipolar power supply overcomes those limitations. Most importantly, it can provide both positive and negative voltages from a single pair of terminals. There are no relays to switch polarity, so a bipolar supply can move smoothly from positive, through zero, to negative voltages. Bipolar Power supply for Battery instruments Circuit Diagram It also regulates zero volts or other very small voltages. In this Bipolar Power supply for Battery instruments circuit diagram to generate regulated ± 5-V supplies from a pair of dry batteries, the circuit of Fig. 1 is commonly used. In order to give protection from inadvertent reverse connection of a battery, a diode in series with each battery would produce an unacceptable voltage drop. The more effective approach is to fit diodes Dl and D2 as shown in Fig. 2, in parallel with each battery. When the supply is switched off, there is the risk of a reverse bias being ...