ATX Bench Power Supply

I’m a computer person normally, electronics had eluded my for many years although there’s always been a curiosity to explore. As an intro I have started playing with Arduinos and gathered a few of the basics

Idecided since I have a unused ATX 500w power supply, my first serious project would be a Bench Power Supply. However, I always like my gadgets to cover a lot of uses. I purchased a couple of years ago a Volt/Amp Meter, and decided to incorporate it into my design. By using a selector switch, to divert any of the rails (3.3v, 5v, 12v, Variable1, Variable2, Variable3 & USB) via the meter, otherwise a direct connection to the output connections.

To further complicate this, I’ve added 3 variable voltages and by using a Boost converter to up the 12v to around 30v (not purchased yet). Then feed this to 3 Buck converters to get the 0 - 30V. I am hoping to achieve 6 - 8 amps in each of these. I aim to replace the pots on the converters to rotary switches connected to the arduino and display. I have bought some grey coded potentiometer and feel if I could source some digital potentiometers, I could further expand the display and features of my Bench PSU. In addition I added a couple of plugs to directly connect to the Volt/Amp meter, and of course an earth socket for my wristband, mat.

I would greatly appreciate some feedback, though please try to be kind. I have spent months researching via many YouTube, electrical forums etc. for information and resulting in my design. If I have gone completely over the top. Just laugh with me. Thanks, in advance.


ATX Power Supply Electricals Connections3.pdf (175 KB)

ATX Power Supply Front.pdf (82.7 KB)

There are a lot of projects that use old computer power supplies as bench PSU's

All I would warn about is that some rails may not have a lot of current so try to identify those.
Specs for each rail are often available at the manufacturer site even for some of the very old ones.

I moved on from those quite a while ago and now have caged supplies in my board / proto / gadget enclosure...

Watch the boost converters...
Had mixed success with those and often its better to step DOWN rather than up.

On my travels I picked up a nice rail mounted 24 volt supply rated at 2 amp which feeds my variable supply.

Other than my caged ones come in at 3.3 Volt, 1 amp, 5 Volt, 4 amp, 10 Volt 5 amp, and 12 Volt 5 amp.

Awaiting some cheap readouts to let me see the actual draw.

There are some quite nice ATX to PSU take off boards on EBay. !

make sure you get one with fuses at least if you go that route

Advantage of the screw type is that it also lets you get at the MINUS voltages.

You have created a magic smoke machine.

The first time you connect a new project to a power supply, you really ought to do so through a variable current limited supply, even the best of us make wiring errors now and then.

PC Supplies might look attractive and cheap, but some rails may put out a great deal of current, which is a problem really, it could vapourise your new project, if you have made a wiring error.

There is also a significant absence of fuses, big mistake.

A box of fuses arrived today, and I do intend on including them, however have yet to decide where. As for the power outlet of the ATX, I do have concerns, and still doing some research on how to cope with that.

As for current limiters, again still in research, though it would be easier if I could just decide on my limits :slight_smile:

Thanks for your responses, already they have me thinking.


If I were you I would discard the ATX case itself.
That will at least allow to put it in a better enclosure and mount the fan and AC input and on/off switch in better locations.

There are lots of fuse boards again available from such as EBay.
For the output side do go with quick blow types.
The AC side can remain as they are often slow blow types.

Panel mount would be my prefered option so you don't have to open the case to change one.

I've already decided on that bob, if you noticed on the front display, you can see the layout I am aiming for using a wooden box I've purchased. The ATX supply will fit inside with all the other boosts, bucks fuses and arduino boards. with the relays of course. Thanks