The article details about a simple voltage stepper circuit also called voltage booster circuit which can be used in cases where the circuit is required to run on a rather higher voltage level than the existing supply.
The purpose of this project is to build a simple voltage stepper, which can be applied on the circuit when the power remain low. On a standard voltage multiplier circuit, the capacitors gets charged via diodes by AC power on one cycle and further discharges in another cycle. This process enable producing peak voltage. But here in this case we are not going to follow this policy. Instead we will adopt a different approach by doubling the DC instead of AC.
The following circuit diagram in Figure 1.0 illustrates the principle to build the voltage stepper:
Referring to the figure, the IC555 is deployed to work as an astable multivibrator, which will generate rectangular pulse on the frequency of around 10kHz. The output of the IC555 is used to gear the transistor T1 and T2. As the type of T2 is PNP, ensure to conduct when the base remain negative, in other words, when the IC's output is low. This will further charge capacitor C4 through D1 diode and T2 is grounded.
On another situation when the output of the IC is in high state, T2 closes while T1 runs. Also during this state, C4 fail to discharge for the diode D1. In this way voltage in C4 and input voltage gets added and enable charge of C5 capacitor via diode D2. Furthermore, the available voltage in capacitor C5 equals to the pulse voltage of VCC over C4 and D1.
Aforesaid is the actual process of the operation. However, to build the system there is few consideration shared for understanding. On a situation when the current is more than 50mA, the regulation gets lost. But on DC voltage, if the current range between 5V – 18V, boosting is possible. Also to derive proper result it is ideal to increase value of C4 and C5 capacitors to 47 µF/40V.
Following are the parts that you need to build the voltage stepper circuit:
| Resistors | |
| R1 | 240 Ω |
| R2 | 5.1 KΩ |
| R3 | 56Ω |
| Capacitors | |
| C1, C2 | 103 ceramic |
| C3 | 104 ceramic |
| C4, C5 | 33 µF/40v electrolytic |
| Semiconductors | |
| IC1 | NE555 or any similar |
| T1 | 2N2222 |
| T2 | 2N2907 |
| D1, D2 | IN4007 |