Safe DC regulated power supply

Safe DC regulated power supply

Direct current regulated power supplies are often used in electronic circuits. However, when the load of a general DC regulated power supply is short-circuited, it is easy to burn out the regulated power supply. If
the regulated power supply fails, it is also easy to cause the output voltage to be too high and burn out. electrical load. In order to overcome the above shortcomings and improve the safety and reliability of the regulated power supply
, a safe DC regulated power supply as shown in the figure can be used .
    The adjustment tube VT1 of this power circuit. Amplifier tube VT2 uses different types of transistors. VT1 uses PNP tubes, and T2 uses NPN tubes.
Resistors R4, R6 and voltage regulator tubes VZ1 and V22 form a voltage regulator tube comparison bridge for voltage error measurement. Its advantages are high measurement sensitivity and
small output resistance, which can provide a larger base current to the amplifier tube, which is beneficial to improving the voltage stabilization accuracy. The starting circuit composed of c2 and Rs is
unique to this regulated power supply circuit. If there is no starting circuit, after the power is turned on, VT1 and VT2 will be in a cut-off state and there will be no output voltage.
    The additional overvoltage protection circuit is composed of resistor R7, a voltage divider composed of potentiometer R, anti-interference capacitor C4, voltage regulator tube V23,
resistor &, thyristor vs and relay K. When the output voltage乩 rises above the value set by RP due to some fault reasons, V23
breaks down, the thyristor VS is triggered to conduct, the relay K is electrically activated, and its normally closed contact K1.1 is broken There is no output when it is turned on, which protects the electrical load.
The overvoltage protection has memory and can only be restored to the cut-off state when the input power is cut off. Normal power supply can be restored only after the overvoltage fault is eliminated.