Fixed Voltage Power Supply


The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current is 1.5A.

Circuit diagram

Fixed Voltage Power Supply-Circuit diagram


  • C1 2200uF 35V Electrolytic Capacitor
  • C2, C4 0.1uF Ceramic Disc Capacitor
  • C3 10uF 35V Electrolytic Capacitor
  • D1, D2 1N4007 Silicon Diode
  • BR1 2A 30V Bridge Rectifier
  • U1 Regulator (See Notes)
  • T1 Transformer (See Notes)
  • S1 SPST 2 Amp Switch
  • F1 2A 250V Fuse and Holder
  • MISC Heatsink For U1, Line Cord, Case, Wire


  • Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case.
  • U1 will require a heatsink.
  • You will need to choose T1 and U1 to match the voltage you want. Use the table below as a reference.

Output Voltage, T1, U1

  • 5V - 6V, 1.5A - 7805
  • 6V - 6V, 1.5A - 7806
  • 9V - 12V, 1.5A - 7809
  • 12V - 12V, 1.5A - 7812
  • 15V - 24V, 1.5A - 7815
  • 18V - 24V, 1.5A - 7818