Has anyone here built their own PSU?

[CaysE]

Just as the title asks. Are quality parts readily available for this kind of project? I imagine the main problem would be designing the PCB... which begs the question, is it possible to buy pre-designed PCBs from manufacturers? What would you use if you could design your own PSU?

[willawake]

Re: Has anyone here built their own PSU?

it would probably end up costing more than buying one ready made and changing the caps.

i can think of more fulfilling projects like nixie clock, headphone amp or tube amp

[tiresias]

Re: Has anyone here built their own PSU?

Hi Cayse,

That's a really great idea for a project actually - it's one I've been considering for some time. Among IT-related 'parts', a PSU has the unique advantage that it doesn't rely on any particularly sophisticated ICs, so the choice/layout of components is largely up to the designer.

Another huge advantage in building your PSU is that you're sure that all the components used are of good quality, and, even more importantly, rated well in excess of the current you're actually going to be drawing. You'd also have excellent reliability, something which is often sorely lacking in many modern ATX power supplies.

It would probably end up costing more than buying one ready made and changing the caps.

It may cost more, but it would the best PSU on the market! An official Badcaps.net PSU, built without cutting corners, and designed by all the electronics gurus/veterans this forum has to offer.

The "ultimate" PC power supply, made "like they used to", and, as a "pièce de resistance", Topcat's Rubycon MCZ as output caps.

[Rainbow]

Re: Has anyone here built their own PSU?

The problem is that you need the transformers.

[willawake]

Re: Has anyone here built their own PSU?

would there be benefits to using toroid transformer? probably not feasible though due to dimensions.

[tiresias]

Re: Has anyone here built their own PSU?

Cayse (and others),

I found a schematic on my hard disk for a switching PSU that I had downloaded some time ago (from the page
www.ludens.cl). It's designed to give a single 13.8V output at 40A, but you'll notice the circuit's similarity to
that found in your classic ATX power supply.

[linuxguru]

Re: Has anyone here built their own PSU?

It isn't easy to build a switching PSU with all the protection and compliance mechanisms. The transformer(s) also pose a problem. You also need decent measuring equipment, including a clip-on current probe, a HV probe, and a storage scope. In general, the first few months of prototyping will involve busting dozens of primary-side switching transistors and bridge rectifiers, often within a few 100 milliseconds after powering up. Add to that, the very real danger of electrocution from accidental contact with the primary side circuitry.

The largest I've built is a 100 W unit, +5v,10A and +12v, 4A; which took all of 6 months way back in 1987. It's easier now, because better transistors, rectifiers and ferrites are available. Also convenient power ICs like the TOP-series and a whole bunch of integrated controllers. It simplifies the design effort, but doesn't change the basic engineering effort to prototype one, including fabrication, test and validation. Not generally worth it unless you're going to sell at least a 1000 units.

[tiresias]

Re: Has anyone here built their own PSU?

The largest I've built is a 100 W unit, +5v,10A and +12v, 4A; which took all of 6 months way back in 1987.

I think I'll have to stick to building little PSUs with old transformers and linear regulators. Not the kind of thing one would power a PC with though - if I wanted that kind of (in)efficiency, I'd use an overclocked 130nm Pentium D and a case full of tacky neon lighting.

Not generally worth it unless you're going to sell at least a 1000 units.

I guess you're right about that. On the other hand, something which I've found to very cost efficient is to string together your own surge suppressors, which avoids one having to buy those glorified powerstrips to connect your PSU/UPS to.

Up to now, my "designs" have been nothing more than a bunch of MOVs, coils and a fuse strung together in a little black box, but I'm sure an expert in the field could suggest some improvements. Hmm - could be material for a new thread...

[japlytic]

Re: Has anyone here built their own PSU?

Some may want to build one which can run off a vehicle or boat supply. Jaycar now stocks a 250W 12V input ATX power supply (XC-4875) for these applications. There are also units for 24V input, as well as 42V input (if you can find one! )

Recently, I've been learning how to modify an old PC power supply for 12-13.8V output (no coil rewinds required!).

[PeteS in CA]

Re: Has anyone here built their own PSU?

E-core transformers are much easier to wind than toroidal. It's also easier to comply with safety regs. And if copper foil is used for the +5V and +3.3V windings (not sure if that's still common practice), well, that just wouldn't work with a toroid core.