EPSU: Eurorack Power Supply Module



The issue 2.1 Oakley EPSU built with the linear option that uses a more traditional 78M05 to create the +5V rail. Note also the 0V bonding point and 0V connection to a 'grounding' 4mm banana plug.

The Oakley EPSU is a triple output (+12V, -12V and +5V) power supply design that is perfectly suited to powering a small to medium sized eurorack modular. Final output current capability is dependant on AC power source, the choice of smoothing capacitors and the heatsink used. However, with a suitable heatsink, capacitors and power source the Oakley Euro PSU has been tested successfully at up to 1A (+/-12V) and 250mA (+5V).

The PSU module must be fitted to a suitably large metal panel to act as a heatsink for the two or three power devices.

It is designed to work with our Euro Dizzy power distribution board. Up to four Euro Dizzy boards may be connected directly to the PCB via the faston connectors fitted to the board. Other makes of distribution board can of course be used.

For safety reasons it is expected that the unit will be used with a external centre-tapped linelump (mains adapter) like the Yamaha PA-20 or PA-30. The PA-20 will allow the PSU module to provide up to 520mA per 12V rail, while the PA-30 will supply up 780mA per 12V rail. The +5V rail can be created with either a standard linear 78M05 regulator or equivalent switch mode convertor.

Greater current outputs can be supported when used with an appropriate transformer or line lump. The board will support mains transformers with either twin or tapped secondaries.

A component level mains transformer should only be used if you know how to connect high voltage wiring. On no account should this project be powered by a component level mains transformer if you are not familiar with fusing, earthing and safe connection of high voltage equipment. For safety reasons Oakley Sound can only endorse using this module with a low voltage input, such as the Yamaha PA-20 or PA-30.

The two main power devices must be fitted to a suitable heatsink to allow heat to be safely taken away. This is the 'switch mode' option which uses a DC-DC convertor for the +5V rail.

The power supply uses standard parts throughout and requires only a simple voltmeter to set up. The circuit board takes less than an hour to build.

Various options are available for different types of switching, earthing and power on indication. The strong glass fibre PCB is silkscreened for easy component identification. It uses generous pad sizes, through plated holes for easy soldering and wide 2oz copper double sided tracks for reliable operation. The PCB is 5.95" (151mm) x 3" (76mm) in size.

Project Downloads

Euro PSU issue 2 Builder's Guide

Euro PSU issue 1 Builder's Guide

Construction Guide Our handy guide to building Oakley DIY projects

Parts Guide Our handy guide to buying parts for Oakley DIY projects

Schematics are only available to purchasers of the PCB and will be sent via e-mail when the board(s) are shipped.


An earlier version of the Oakley Euro PSU driving three Euro Dizzy boards on a rear mounted 4U high 19" rack panel.

The three pin power socket for use with external PA-20 and PA-30 power supplies.

A direct mains powered EPSU driving four Euro Dizzy boards.

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Copyright: Tony Allgood.
Last revised: September 28, 2023.