Simple 12V To 24V VOLTAGE DOUBLER

Many electronic circuits require a voltage higher than that available from the power supply.

- SURESH CHANDRA DWIVEDI

For example, when only a 12V battery or adaptor is available but a circuit requires 20V to 24V, a voltage-boosting arrangement becomes necessary. One simple and economical solution is a charge-pump voltage doubler driven by an oscillator.

The system is suitable for small power supplies, op-amp circuits, analogue electronics experiments, and various DIY applications that require a moderately higher DC voltage from a lower-voltage source. Fig. 1 shows the author’s prototype.

Circuit and working

Fig. 2 shows the circuit diagram of the voltage doubler system. It is built around the NE555 timer (IC1), transistors BD139 (T1) and BD140 (T2), and a few passive components. The system consists of four main sections: the oscillator stage, the driver stage, the voltage-doubler network, and the output filter stage.

IC1 (NE555) is configured as an astable multivibrator to generate a square-wave signal. Resistors R1 (4.7kΩ) and R2 (22kΩ), together with capacitor C2 (0.1µF), set the oscillation frequency to approximately 3kHz. Capacitor C1 (0.01µF) is connected to the control-voltage pin to improve stability and reduce noise.