Voltage Inverter

This simple circuit is a good solution to the powering a dual supply op amp from a single battery problem. The circuit simply takes a positive voltage and inverts it. It uses only one 555 timer and a few other passive components, so it doesn't add much in the way of size and cost to a project.

Schematic

Parts

Part Total Qty. Description Substitutions R1 1 24K 1/4 Watt Resistor R2 1 56K 1/4 Watt Resistor C1 1 3300pF 25V Ceramic Capacitor C2 1 47uF 25V Electrolytic Capacitor C3 1 10uF 25V Electrolytic Capacitor C4 1 100uF 25V Electrolytic Capacitor D1, D2 2 1N4148 Silicon Diode U1 1 555 Timer MISC 1 Wire, Board

Notes

1. V+ can be anywhere from 4 to 16V. -V is one volt less than V+. So for -12V output, use +13V input. The maximum current output of the circuit is about 280mA, more than enough for a few op amps.
2. For better regulation, a 79LOxx series regulator can be used.
3. A zener diode may also be used to regualte the output voltage.
4. Thanks to audioguru for correcting some errors in the original schematic. Read about it in this forum topic