2.5 to 24V continuously adjustable regulated power supply

The picture below is a regulated power supply formed by using TL431 as the voltage reference and driving the field effect transistor K790. Its output current is large, reaching about 6A.

The working principle of the power circuit is as follows. After the 220V voltage is stepped down by transformer T, rectified by D1~D4, filtered by C1, and the voltage doubler circuit composed of D5, D6, C2, and C3, the voltage Vde=60V; Rw and R3 form a voltage dividing circuit; TL431 and R1 form a sampling amplification Circuit; 9013 and R2 form a current limiting protection circuit; FET K790 is used as an adjustment tube (can be used in parallel directly); C5 is used for output filtering. The voltage stabilization process is: when the output voltage decreases, the potential of point f decreases. After the internal amplification of TL431, the voltage of point e increases. After adjustment by K790, the potential of point b increases. On the contrary, when the output voltage increases, the potential of point f increases. , the potential of point e decreases, and after adjustment by K790, the potential of point b decreases. This stabilizes the output voltage. When the output current is greater than 6A, the transistor 9013 is cut off, thereby limiting the output current to achieve the purpose of current limiting.

The resistor R1 is selected to be 2w, and R2 is selected to be 5w. The parameters of other components are as shown in the figure, and there are no special requirements.