Free Circuit Diagram

If only a 5 volt positive supply is available and you need a negative voltage for op-amp or other biasing purpose, the you can generate the negative supply from the positive supply using this circuit.

This circuit give same functionality with our previous 555 switching circuit, but now we use a CMOS inverter gate. Using CMOS [...]

If you need a negative supply for op-amp or just need negative bias voltage while operating from a single supply voltage (for battery operation for example), this circuit helps providing the negative supply for you. The circuit is based on charge pump driven by 555 switching circuit. Here is the schematic diagram:

The negative voltage [...]