An interesting application in case of needing to supply an operational amplifier or a very low power voltage comparator is shown in figure. This circuit consists of a symmetrical 10 + 10 V power supply that operates from a single input of 5 V. This is a positive folder and a negative folder on the same circuit. Three 4049 inverters form an oscillator that determines the rate of operation of the inverter and at the same time excite the other three inverter ports in the negative section of the voltage multiplier. The values of the components are typical and changes can be made according to the application. TTL inverters can also be used in equivalent configurations, with due changes in component values.
