Reducing Wall Warts with ATX PSU
Running out of power outlets at the desk seems like a common problem. It seems like everything has a wall wart, and virtually all the wall warts are either 5V or 12V PSUs. That's also what ATX PSUs output!
This documents my adventures in replacing those wall warts with a single ATX PSU.
This actually does require at least one device of each 5V and 12V to be used. ATX PSUs expect both those rails to be used, and if they aren't, the PSU can eventually experience problems. Fortunately, there seem to be plenty of both voltages used by USB hubs, network switches, charging devices, raspberry pis/beaglebones, etc.
- An ATX PSU. I had a Corsair TX750 laying around, so that's what I'm using. It is rated at 80%+ efficiency, andis very quiet.
- Molex 4pin Power to 5V USB
- USB to 5.5mm/2.1mm DC Barrel Jack
- DC Barrel Plug fanout cable
- DC Barrel extension cable
SetupTo ensure the ATX PSU powers on and stays on, find the largest connector coming out of the PSU. This is the connector that normally goes to the motherboard of the computer. Short the green wire to any black wire. This will ground the power on pin, and will ensure the PSU stays on. I just used a paper clip between those pins.
USB is 5V, so if your device is powered by USB, that's pretty straightforward. Use the Molex 4pin Power to 5V USB cable listed above, to get a USB jack that only has power.
Most devices use the DC barrel jacks. I've found nearly all of my devices that take barrel jacks use 5.55mm/2.1mm sized jacks, with center positive polarity (the outer ring is ground and the center carries the power). For 5V devices that use this, the USB to 5.5mm/2.1mm DC Barrel Jack works great in conjunction with the molex to usb cable above. If you've got lots of devices close together, use the DC Barrel Plug fanout cable to keep open power connectors.
12V is more of a problem. I have not found any Molex 4pin power connectors to DC barrel jack cables premade. Instead, I purchased 5.55mm/2.1mm male barrel connectors from Radio Shack and soldered them to chopped up 4pin molex splitter cables like these. Combined with the DC Barrel Plug fanout cable, you can get quite a few hooked up without making too many cables.
For devices that need a little more reach, DC Barrel extension cables can help. Particularly off of the fanout cables.
NotesSome random thoughts about using this setup for a couple months:
Most mobile phones are getting picky about their chargers, and won't actually charge from the 4pin molex to USB adapters above. Behavior varies by phone, some need to actually negotiate with a USB host, some want the D+/D- pins shorted, etc.
Other than the mobile phone issue, I have been using this successfully with:
- AT&T microcell (12V)
- USB hubs (generic, 5V)
- Netgear ethernet switches (12V or 5V depending on model)
- Raspberry Pis (5V, no more worrying about sufficiently beefy PSU!)
- Beaglebone Black (5V)
- Belkin BT AP (5V)