ATX PSU switched Aux. AC out?
Posted on 2001-07-22
AT PSU's often had a useful auxiliary AC power-out switched via the main case switch. This meant you could power on and off printer, monitor, audio, MIDI devices, Palm cradle etc. all with a single switch.
With ATX PSU's the AC power-in is transformed and rectified and feeds the 5VSB output, so the PSU can be "woken-up" by case switch, LAN, Modem, Mouse double-click, or software. This usually means that any auxiliary AC power-out is hard-wired to the AC power-in. Thus if the power in is left on for "wake-up" purposes, any peripheral device connected to the aux AC out is also on and needs to be switched on/off separately. In which case, you may as well use a separate AC feed as use the aux AC on the ATX.
Does anyone make an ATX PSU where the aux AC out is switched "usefully" by the wake-up? Failing this, what is the easiest way to modify the PSU so this happens?
e.g. 12V coil relay across wake-up operated -12V to Ground with mains AC across relay outputs? Has any one done this successfully? Is there enough power on the 12V stage to handle a relay which will be "on" whenever the ATX PSU is in woken-up state?