NE555 voltage doubler circuit, boost circuit

Only using the timer IC555 to form a charge pump can obtain a high voltage of N times the power supply voltage. This is a voltage doubler rectification circuit composed of diodes and capacitors. The basic circuit is shown in Figure 1 (omitted). It is a combined unit of two diodes and two capacitors. Connect this unit to the output end of the 555 charge pump, as shown in Figure 2, to form a double voltage circuit. An output voltage that is twice the supply voltage can be obtained. Theoretically, (N+1) times the voltage can be obtained by connecting N units in series. However, in the actual circuit, since the output voltage of the 555 is slightly lower than the supply voltage, and each unit diode has a forward voltage drop VF, the output voltage of the voltage doubler circuit is lower than the theoretical value. For example, when the power supply voltage is +12V, the actual no-load output voltage from 2 times to 7 times the voltage will be lower than the theoretical value. Figure 3 is a 3x voltage circuit.

The output current capacity is about 20mA at 3 times the voltage, and the current decreases by 1/2 for each additional unit. The output voltage decreases as the output current increases. According to the component value of .555 in the figure, the oscillation frequency is about 950Hz.