Discrete component DC boost circuit diagram

The figure below is a low-power DC/DC converter circuit composed of transistors. Among them, Figure (a) is a circuit that converts a +5V input voltage into a -12V output voltage , and Figure (b) is a circuit that converts a +5V input voltage into a +12V output voltage. For any circuit, if the output voltage exceeds the stable voltage of the voltage regulator tube VDw, negative feedback is applied to the drive transistor VT1 to keep the output voltage constant. Therefore, the output voltage is equal to the stable voltage of the voltage regulator tube. If the stable voltage is changed, the output voltage can be adjusted.

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When the circuit does not vibrate, just change the value of capacitor C1. The output current is 15~20mA, the voltage stability is about 5%, and the efficiency is 80%~90%.