Dual power supply is a very essential part in the laboratory or in your work while there you use op-amps in your circuit. Most of the opamp Ic's require dual voltage supply. But it's difficult to provide dual power supply as it's costlier than a single battery.
|Circuit diagram of Dual power supply from single battery: Click on image to enlarge|
Here's circuit that provide both +9V and -9V from single 9V battery. It consist of the basic timer NE555 and a negative voltage regulator IC LM7909 as main parts. The boosted voltage is made ripple free by the negaive voltage regulator.
The timer IC is configured as a astable multivibrator of 100KHz frequency and is boosted using a villard cascade voltage multiplier. As the output frequency of the multivibrator is far beyond the AF range, it will not picked up by the audio amplifiers and other devices working in the AF range.