Op-amps require dual-polarity supply for proper operation. When working with battery supply, it becomes difficult to get dual power supply for the op-amps. Presented here is a simple circuit that provides ±5V from a 9V battery.
Circuit and working
The circuit diagram for the ±5V supply from a 9V battery is shown in Fig. 1. It is built around 9V battery (BATT.1), voltage regulator IC 78L05 (IC1), CMOS voltage converter ICL7660 (IC2) and a few other components.
Voltage regulator IC1 converts 9V battery input into regulated 5V. This 5V output from IC1 is given to pin 8 of IC2. IC2 and capacitors C3 and C4 form the voltage inverter section that converts +5V to -5V. Converted -5V supply is available at pin 5 of IC2. Converted ±5V supply is thus available at connector CON1.
Construction and testing
An actual-size, single-side PCB for±5V supply from 9V battery is shown in Fig. 2 and its component layout in Fig. 3.
Assemble the circuit on the PCB and enclose it in a water-proof box. Battery BATT.1 should be enclosed in the box. Fix CON1 on the front or rear side of the cabinet, so that you can use the ±5V easily.
Before using the circuit, verify the test points given in the table to ensure proper working of the circuit.
Download PCB and component layout PDFs: click here
A. Samiuddhin is B.Tech in electrical and electronics engineering. He has been an electronics hobbyist since ninth standard.