Regulated power supply

1.3 ~ 25 V voltage adjustable voltage circuit diagram
The regulated power supply adjustable range is adjusted between 3.5 V ~ 25 V.Output current is big.And uses the adjustable voltage regulator tube circuit.Thus satisfied with the stable output voltage.
Working principle:
After rectifying filtering the dc voltage is provided by R1 to adjust the tube base and make adjust tube conduction.In V1 turn-on voltage through the RP,R2 make V2 open,Then the V3 open.Then V1, V2, V3 emitter and the collector voltage no longer change(Its role as regulator tube completely).Adjust the RP,Steady output voltage can be obtained.R1, RP, R2 and R3 ratio decide circuit output voltage value.
Component selection:
Transformer T choose 80W～100W,input AC220V.Output double winding AC28V.FU1 chooses 1A,FU2 chooses 3A-5A.VD1 VD2 choose 6A02.The RP chooses about 1w ordinary potentiometer.Resistance value is 250K-330K.C1 chooses 3300uF/35V electrolytic capacitor, C2, C3 choose 0.1uF monolithic capacitors, C4 chooses 470uF/35V electrolytic capacitor.R1 chooses 180-220Ω / 0.1W ~ 1 W, R2, R4, R5 choose 10 k Ω, 1/8 W.V1 choose 2N3055 ,V2 chooses 3DG180 or2SC3953, V3 chooses 3CG12 or3CG80.