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2N3055 Variable DC Voltage Power Supply

This is a schematic (circuit diagram) for a relatively simple variable-voltage DC power supply, with 0.7-24 Volts DC and 0.05 - 2.0 amps current.

Screenshot: 2N3055 Variable DC Voltage Power Supply

The main power transistor used is the 2N3055, a common NPN transistor used in high current DC power supplies. The 2N3055 can be replaced with the slightly less powerful TIP3055. The other control transistors used in the circuit are 1 x BC182, 1 x BD139 and 1 x BC212.

Instruction are given regarding the potentiometers, heatsinks, etc.. Enjoy - let us know if you build this DC power supply circuit, and how it works out!

COMPONENTS:
  • Potentiometers:
  • P1 = 500R Linear Potentiometer
  • P2 = 10K Log. Potentiometer
  • Resistors:
  • R1,R2 = 2K2 1/2W Resistors
  • R3 = 330R 1/4W Resistor
  • R4 = 150R 1/4W Resistor
  • R5 = 1R 5W Resistor
  • Capacitors:
  • C1 = 3300μF 35V Electrolytic Capacitor (see Notes)
  • C2 = 1μF 63V Polyester Capacitor
  • Diodes:
  • D1,D2 = 1N5402 200V 3A Diodes
  • D3 = 5mm. Red LED
  • Transistors:
  • Q1 = BC182 50V 100mA NPN Transistor
  • Q2 = BD139 80V 1.5A NPN Transistor
  • Q3 = BC212 50V 100mA PNP Transistor
  • Q4 = 2N3055 60V 15A NPN Transistor
  • Misc:
  • T1 = 220V Primary, 36V Center-tapped Secondary (50VA Mains transformer [see Notes])
  • PL1 = Male Mains plug
  • SW1 = SPST Mains switch
 
Alternate References:
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