Constructional difficulty: Moderate
if using a low voltage AC output mains adapter.
A completed issue PSU2 board. This one is
powered from an internal mains transformer so has the switch
terminals linked out.
The Oakley PSU2 is a dual output +/-15V
power supply based around the LM317 and LM337 regulators that is
perfectly suited to powering a small to medium sized Oakley
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 PSU2 has been tested successfully at up to 1.2A per
rail.
The PSU2 module must be fitted to a
suitably large metal panel to act as a heatsink for the two power
devices.
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 15V rail, while the PA-30
will supply up 780mA per 15V rail.
Greater current outputs can be
supported when used with an appropriate transformer or line lump,
and suitably large heatsinks. 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 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 copper double sided
tracks for reliable operation. The two layer PCB is 133mm x 76mm.
Chunky screw terminals are used for the PSU2’s
output connections. M4 ring terminals are crimped onto the
connecting wires.
Power Supply for 19″ Racks
A PSU2 module with internal mains
transformer mounted to a 5U high panel at the rear of a 5U high
19″ rack case.
The PSU2 module can be mounted
to a 4U or 5U high 19″ blank faceplate. These blank panels
are available from various sources and are typically made from 2.5mm
or 3mm thick black anodised aluminium so are easy to drill. The
panel would be normally fitted to the rear of your modular’s 19″
rack case. Because of the generous surface area the panel acts as
a very good heatsink. This design is suitable for connection to
either the PA-20 or PA-30 power adapters for supplying currents
of up to 0.52A or 0.78A per rail respectively, or, if you know
what you are doing, fitting a mains transformer and appropriate
switch, fusing and inlet socket.
An original Oakley PSU module mounted to a
4U high panel at the rear of a 6U high 19″ rack case. Raw
power is supplied via a PA-30 line lump supply that connects to
the three way socket seen on the right hand side of the panel.
The green 4mm banana plug connects to the PSU’s 0V connection to
tie to other modular cases.
Project Downloads
Construction
Guide Our handy guide to building
Oakley DIY projects
Parts
Guide Our handy guide to buying
parts for Oakley DIY projects
A nearly complete PSU2 waiting to be fitted
onto the panel and its two regulator ICs.
Prices
Click here for ordering
details.
PSU2 issue 1 PCB
………………………………………….. 17GBP
3-pin power socket for external PSU
…………………. 2.50GBP
All of the other parts should be able to be
purchased from you usual electronic component supplier. Please
see the Builder’s Guide for more details.
See the Oakley Sound ordering
page for ordering information, shipping charges and payment
methods.
All prices include VAT at UK rates.
Shipping/postage is additional to these prices. See also the FAQ page.
The three pin power socket for use with
external PA-20 and PA-30 power supplies.
Back home