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.
| 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 | |
| |
- 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.
- For better regulation, a 79LOxx series regulator can be used.
- A zener diode may also be used to regualte the output voltage.
- Thanks to audioguru for correcting some errors in the original schematic. Read about it in this forum topic.
