The Power Supply
Safety Warning
The RPSU supply module has been designed to work with isolated low voltage AC inputs only.
Connection to any alternating current supply is done at your own risk. Low voltage is classified as
being less than 25V with respect to the ground potential. Voltages above this level can, and often
are, lethal to living creatures.
Oakley Sound Systems will not advise on building or modifying this board to allow for direct
connection to the mains, or other high voltage sources, further to what is provided in this document.
Please do not ask me for additional information pertaining to direct mains connections or using
internally mounted transformers as I will not give it.
For safety and legal reasons I cannot recommend powering this board from any other supply
than low voltage AC output mains adapters.
Oakley Sound Systems are not liable for any damages caused by the misuse of this product. It is
your responsibility to use this product safely. If you have any doubt about installing a safe power
supply, then please do not attempt to do so.
Single Phase AC output wall wart supply
These are the most common AC output power adapters but increasingly they are getting harder to
find particularly at higher output currents. Most wallwart supplies produce DC (direct current)
voltages which means they are not suitable for use with the RPSU. Ensure that when you buy a
wallwart type adapter it does actually output an AC (alternating current) voltage. Some DC output
adapters are confusingly called AC adapters simply because they plug into your AC mains supply.
The SRE330 requires around 650mA or 0.65A from a single phase 15V AC supply. That means
you need to find one with
at least
this capability. A 15V 1A device would be perfect, but a 15V
0.5A would not. An 18V AC supply would also work but again at least 0.65A is required.
Quite often you will find power supplies not rated in amps but instead given an overall maximum
power rating, or wattage. The maximum amount of current that can be taken is worked out by
dividing the power rating in watts by the voltage output. The problem is that you don't often know
the exact voltage the device is producing since it does vary a lot from what it says on the device.
For example, a 15V supply may well be producing 18V even when at full load. Even so a 15W 15V
AC device should work fine. A 10W 15V one however, although in theory should work, in practice
it may not.
Ultimately, the proof of whether it works is twofold. It must firstly produce the correct voltage so
the RPSU can actually create a /-15V when driving the SRE330. And secondly, the adapter
must not get overly warm in use. If you've bought what should be a good adapter but it gets hot or
hums loudly when powering the SRE330 then it is not suitable. Another solution must then be
sought.
