The Oakley Power Supply Board
The issue 4 PSU board from Oakley Sound Systems.
The power supply board will allow the conversion of a suitable low voltage alternating current
(AC) to be rectified, smoothed and regulated for operation with the Oakley Modular. The
module is designed to be fitted to a suitably large metal panel which functions as a heatsink for
the series pass devices connected to the PSU circuit board. This metal panel should have
adequate airflow around it. An example of such a panel is the 3U wide master panel which
also contains a handy multiple and power switch. You can also use a 4U or 5U high 19” rack
blank panel. These are particularly suitable if you are mounting your modular synth in a 19”
rack. The greater surface area on the 19” blank panel allows you to mount not only the power
supply module but also up to two Dizzy PCBs. And the greater surface area also allows the
power supply's power devices to dissipate more heat safely and that means a greater current
output should you need it.
The voltage output of the power supply module is a split rail or bipolar 15V supply. This
means it generates both +15V and -15V. That is, two power rails, one of a positive voltage,
the other a negative one. It's sometimes written as +/-15V. These voltages are measured with
respect to a common ground which is normally connected, via your house's wiring, to the
earth that you stand on. The voltage across both rails is 30V, with the common ground sitting
exactly in the middle of this at 0V.
The output current capability is the maximum current you can draw out of the power supply.
The current taken from the supply is, for the most part, determined by the amount and type of
modules you are connecting to the power supply. However, the actual patch also has an effect
on the current draw – the more outputs that are connected to inputs increases the current
draw slightly. Also, some LEDs when lit may increase the current draw.
The Oakley PSU features current limiting. This sets the maximum current the power supply
will actually provide. If you try to draw more than the limit the output voltage will fall to
maintain the current at the limit value. The current limit is set by two resistors, R2 and R3, on
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