The voltage stabilization principle of the output voltage stabilizing circuit

The voltage stabilization principle of the output voltage stabilizing circuit

VD01 acts as a voltage stabilizer, providing a fixed potential for W1. Adjusting the adjustable resistor W1 can change the potential of the end of R7 close to W1, thereby changing the potential of U1+. In the picture, I think V4 acts as a clamp at 0.7V. It is estimated to have a protective effect, that is, adjust the potential of the other end of the adjustable resistor W1 and R7, that is, the positive end of V4 will not exceed 0.7V (this can ensure that the B-pole voltage of Q2 will not be too large after U1 is compared and amplified, and the maximum is only 0.7V. Enough), R6 plays the role of feedback voltage stabilization, R5 is the current limiting resistor, and V3 plays the role of protection (if the voltage is too high, it can cause breakdown protection). Therefore, if the voltage at the V4+ terminal increases, the voltage at the output terminal of U1 increases, the conduction of Q2 increases, and the current flowing through R2 also increases, thereby increasing the conduction of the B pole of Q1, and the potential of Q1 C pole to ground Decrease, so the absolute value of the potential of the VOUT output to the ground increases. I think the adjustable potentiometer can be used to measure the potential changes of each node to obtain the principle information! As for how to modify it, it may be troublesome to modify it based on the original circuit. The polarity of the bridge stack output must be changed, the polarity of V1 must be changed, the transistor must be PNP, and the input terminal of U1 must be a phase-changing input, and its - terminal must be used as the feedback change terminal, and its + The terminal is used as a fixed comparison terminal, V3 and V4 are swapped, and the voltage at one end of W1 must be changed to negative voltage for debugging. For other resistors, it can be debugged and then confirmed!