Hey! I’m planning to build a PSU for my very first modular case, and I was wondering why we don’t simply use computer PSU, since those are powerful, can deliver GND, +12v, -12v, +5v, and are quite common.
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This has been discussed before, but briefly computer PSUs use switched regulators which may not by that great for audio, aren’t really designed for systems that want relatively symmetrical ±12V but hardly any 5V, and are usually massively over-dimensioned for some voltages and under-dimensioned for others. So they’re no silver bullet, but if you don’t mind the drawbacks go ahead and try it.
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Thanks for reply! I’m probably going to use one to test my first 3340 VCO, and build that FC PSU when I get enough pocket money 
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One thing to keep in mind is that a computer PSU can sink a lot of amps into your circuit, and cause a lot of damage if you’ve made a mistake. You can use something like
to get a bit of extra protection (it has polyfuses that turns things off at 1.25 A, long before the PSU detects a short, but that may still destroy things). But the beefier your supply, the more careful you need to be when powering things up the first time.
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I’ve got a few of these:
Got the ±15V ones and followed the diagram in the listing for a low-noise ±12V supply. It works a treat and means my TL074 mixer circuit can run off a USB lead.
For my noise crate I’ve got an isolated ±12V buck converter from the same supplier, which I run off a 48V supply. It’s a nice clean supply (I included a couple of chunky capacitors just out of common decency).
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I’ve been using a 250w atx supply since i started.
Also my bench power supplies are atx and have used them for a lot of other projects.
Switching supplies are supposed to be noisy but i have never had problems with any switching noise in the audio range, plus you can add some more power conditioning at your modules, like capacitors and ferrite bead or resistor of a few ohms.
I have a number of tube modules, if i power on the atx with them all connected it doesn’t power up, so i then have to switch on the 12v manually.
It has some other safety features to be aware of but in my experience an atx works pretty well
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IMPORTANT NOTICE:
Atx power supplies are not isolated from the mains. This ‘shouldn’t’ be a problem if your mains is wired correctly, and if you check the polarity.
And of course if you don’t go poking around in it while the supply is plugged in.
I only just noticed the problem when i moved my synth into the basement, where there also turned out to be an earth fault. I live in the eu where mains sockets are not polarized, so i probably have live and neutral switched between 2 devices.
I got a shock when i touched a metal panel while holding a patch cable with a metal jack.
Though it was only a mild tingle, it is definitely something to watch out for.
It also happened when i was using my oscilloscope. But not when i held the cable plugged into my guitar amp.
We recently had a technician install a new fuse box with smart meter, the large main safety earth wire going to the earth pin in the basement, was very poorly connected. The wire was corroded, as well as the water pipe it was connected to. From there, there was another corroded wire going to the earth block. I measured 3k ohms between safety earth and the earth pin in the basement.
This is not how safety earth should be connected, and no one in the house ever had a clue.
After further inspection, live and neutral are also switched around in some sockets.
Bottom line is: don’t blindly trust the mains wiring in your house. Appliances with exposed metal parts should ALWAYS be connected to safety ground, which also should be connected properly.
I’ve never had technical reasons not to use atx’s for my projects, but safety is most important.
I don’t recommend using atx supplies anymore, unless you have a very clear understanding about electrical safety
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Yikes! Be safe everyone! 
Ive said it before and again, but we have cheap DIY power supplies out there that fill the niche without needing to find even cheaper solutions.
Power isnt the place to save a dime.
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