High Current 5V Regulator

When doing WSPR on the Raspberry Pi, I needed a bit more current than the standard mobile phone chargers suggested for the Pi could offer. Typically they’re rated at about 1 amp, and will do 500 mA with a clean output supply but much beyond that the output gets noisy and the voltage drops (there are some exceptions). As I was interested in receiving weak radio signals the switching noise from the power supply was a nuisance as was the weird behaviour of some of the peripherals. As you so often see in the Pi forums, “It’s your power supply”.

I had originally made something using a 2N3055 in series pass, as shown below, but I came back to this project some years later and refined the approach as well as adding some extra filtering. 

The New Design

The new design uses three ON-Semi MC7805 devices combined with a Schottky diode to give around 5.2V output. There’s an inductor after the regulator to filter the regulated supply further, and plenty of decoupling. The design offers three 1A outputs, which can be linked to provide a total current of 3A.


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The board is a 2-layer board with multiple ground zones and is therefore offered as a commercially manufactured PCB.

If you are interested in such a board, please Contact Me.

Bill of Materials

The design uses fairly inexpensive parts, which are commonly available from electronics suppliers as well as places such as eBay and Amazon.

Component ReferenceComponent ValueComponent Package
C1220 µF0.125″ pin spacing radial capacitor
C2, C3, C5, C6, C7100 nF1206 or 0805
C4, C8, C910 µF0.125″ pin spacing radial capacitor
D1, D2, D3LED1206 or 0805
D4Schottky Diode1206 or 0805
J1DC Power Socket5.5 x 2.1mm
J2, J3, J4USB A SocketThrough-hole USB-A
J5, J6Jumper0.1″ pin spacing header
L1, L2, L3100 µH0.2″ pin spacing radial inductor
R1, R2, R31 kΩ1206 or 0805
U1, U2, U37805 (>1A variant)D-PAK package

The Old Design

The design presented here isn’t the greatest or most reliable; it’s the easiest to do the job well. The big 2N3055 transistor used as a series pass transistor is probably overkill for the couple of amps required here, but as it’s well under-rated, it should easily do! It’s important to note that there is no short circuit protection and no over-current protection. Short the output and you’ll get all the current the supply can manage (plus a hot or blown 2N3055). You’ve been warned!



Below is the schematic for the regulator. The design is very simple. U1 is a LM 7805 5 Volt regulator. This provides the 5V reference to Q1 which is configured in series pass – the emitter of Q1 is at 5V but with more current than would be provided by the 7805. Diode D2 gives a slight offset to the reference voltage of typically 0.7 Volts which overcomes the 0.7V loss at the transistor’s base-emitter junction.



Just in case anyone is interested in making this project, I have included the PCB masks.

Bottom Copper Mask
Silk Screen


Below are the download links to the board mask and silk as PDF which can be printed at 100% to provide toner transfer or optical masks. Also included is the Gerber files for milling boards.

An online scrapbook full of half-baked projects and silly ideas.