Single End Power Supply

Need a small power supply for a project? This one is based on the LM340 or 78xx series regulator. It can be constructed for +5, +6, +9, +12, +15, +18, or +24 volts DC.

This supply was initially designed for a small headphone amplifier circuit, and LED VU meter driver, but I soon realized it had a lot more applications. As you can see it’s a very simple design using a few diodes, three capacitors, a regulator, resistor, LED, and two connectors for the transformer connection and DC out (if you choose to use connectors).

The project was designed with a slightly more expensive snap-in capacitor because I found this circuit to be very helpful not only in the headphone amplifier, but also my relay switching panel for my amateur radio antenna system, a console project I have been working on, and a switching board that I’m using in our production trailer at work.


The circuit is very simple and you might as well breadboard it, but I decided to make up PC boards so it looked professional inside equipment. After all, people judge you by results and the quality they perceive by looks, rather than how clever you can be by using a stryrofoam McDonalds hamburger box for the PCB. The corners are marked for supporting posts, which can be drilled out for (US) 4-40 or 6-32 treads. The limitation of this circuit is the capacity of the regulators to carry current. Typically, I don’t like to exceed 750 milliamps of current on these regulators for dependability.

This part list is for the 5 VOLT version. Modify as necessary for other voltages. All parts were purchased from Mouser Electronics, and can be purchased over the phone or on their web site.

  • C1 = .1 uf Capacitor, .1 uf @ 50vdc, 20% (Jameco 25523)
  • C2 = 5,600 uf Capacitor, 5,600 uf @ 35vdc(wv) (Mouser 5985-35V5600)
  • C4 = 1.0 uf Capacitor, 1.0 uf @ 35vdc(wv) (Mouser 647-UMF1V010MDD)
  • D1 = 1N4005 Diode, DO35-10, (Mouser 625-1N4005E-E3/54)
  • D2 = 1N4005 Diode, DO35-10, (Mouser 625-1N4005E-E3/54)
  • D3 = 1N4005 Diode, DO35-10, (Mouser 625-1N4005E-E3/54)
  • D4 = 1N4005 Diode, DO35-10, (Mouser 625-1N4005E-E3/54)
  • AC = L02P Header, Polarized 2P (Mouser 571-6404552)
  • DC = L03P Header, Polarized 3P (Mouser 571-6404553)
  • IC1 = 7805 IC, Regulator, LM340H-05 (Mouser 595-UA7805CKCT)
  • PWR = LED LED, Through Hole, Red, Non-Diff (Mouser 596-SSL-XL0938ID)
  • R1 = 330W Resistor, 330W, ΒΌ watt, metal film 1% (Mouser 271-330-RC)
  • PCB = SPS-1 PC Board only. (HF-Antenna SPS-1)
  • PCB = SPS-1C PC Board Completed. (HF-Antenna SPS-1C)

About Frederick R. Vobbe

Now retired, my 50+ year career has included recording studios, radio & television stations. I have multiple hobbies, and have worked as a tech to corporate management.
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