This circuit contains a 555 timer with 2N2222 transistors and an external potentiometer. This potentiometer adjusts the output voltage to the desired value. To regulate the output voltage, the 2N2222 changes the control voltage of the 555 IC to increase or decrease the pulse repetition rate. A 1.2K resistor is used as the collector load. The base of the transistor is driven by an external potentiometer. If the output voltage is negatively reduced, the control voltage is closer to ground, causing the 555 repetition rate to increase.
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