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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
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.
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