12V AC power supply rectifier diode form VD1. VD4 rectifier bridge circuit

This power supply circuit consists of 12 volt AC power rectifier diodes in the form of VD1... VD4 rectifier bridge circuits. The rectified voltage is stabilized by capacitors CI, C2, Zener diode VD5, and transistors VT1 and VT2. diodeThe output voltage of the power supply from 0 to 12 is regulated by the variable resistor R2. The maximum current of the power supply (300mA) that abandons the load is limited to allow direct current rectification diode.

The rectifier diode can be used for any letter index in D226 or D7. Variable resistor R2- power switch, it is a desirable group A, with its size, and the output voltage of the power supply set on it is equally numbered. Can be used in MP39 MP40 transistors, diode rather than transistor stability .. . .. MP42， Instead of P213-P214... P217 transistors, P201, P4 with any letter index. The gain of the transistor must be at least 15. Zener diode D813 can replace Zener diodes D811, D811D, and D814G. The maximum pressure of the power output voltage will correspond to that used to prevent Zener stabilization. The scale of resistor R2 should be calibrated by connecting the voltmeter to the output terminal block.diode

Parts List:

R1，R2，R3：1K

C1，C2：500uF/25V

D1：D813

Question 1: MP39

Q2：P213

VR1：10K