My controller has -3.3V, -5.0V, -12V, +3.3V, +5.0V, +12V, +24V and +36V supplies available so I win!!


There seems to be some misunderstanding in the last few posts about the significance of current/power rating of supplies. To clarify...

If you install a 12V supply rated at120W then the unit CAN deliver a current up to 10 Amps but in practice will deliver the current required by the load. If that is only 1A, the supply will deliver 1A. This is a power of 12 Watts. The power drawn from the 240V mains will be 12W divided by the efficiency of the supply. Switch mode supplies like the ones in the photographs typically have an efficiency around 85% so you will draw 12/0.85 Watts from the mains, about 14W. That gives 2W of waste heat.

If you decide to install a 12V supply rated at 240W instead, the maximum current it can supply rises to 20A. ALL the following results, including electricity used and waste heat stay the same. The only changes are that the supply will be physically bigger and cost more.