I’d be interested to see what a Kill-A-Watt or other power measurement meter clocks his rig w/ a standard PSU vs. his home brew PSU…

I’d also like to point out that I’m using an 8 year old Pentium-M HP laptop as a server of sorts at my house… it’s been running since 2003 w/ very little interaction (other then network stuff). It consumes 22W under normal operation (lid closed) which includes a 4200rpm HDD.

@hmbemis – I run a pair of laptop boards, each with no LCD, optical drive or anything but a shared 120W 19V adaptor between them… They mount quite nicely on their own LCD back cover with standoffs and hot glue :) One was a DV6000 (chipset repaired- Quite nice with 4GB DDR2-800!) and a GM965/P8100 (but limited to DDR2-667… Lame)

But +1 for low-power servers instead of 400W idle gaming behemoths left running all day to download torrents and stream video over internets.

I believe this may have missed the efficiency boat. I don’t see a flyback/switch mode circuit on the front end. I see AC mains being stepped down, bridge rectified, smoothed, then put through a switch mode module. So the benefit of a flyback style circuit is lost regardless of the fact that after being stepped down some switch mode modules are being used.

Alright, let me address some of the comments.

Price: I got the toroidal transformer and the RIFA cap for free and TI boards relatively cheap. Agreed that this probably isn’t worth building if you have to buy all the parts though. But I’m not really telling anyone to do so. This is just a project log.

Just buying it: See above. A picoPsu or similar bundled with a reasonable quality SMPS adapter brick would’ve cost more than I spent on this project. And while It’s true that you can get a 12v some amp chinese adapter for peanuts I don’t think I’d want to run my 24/7 home server off one ;)

Efficiency: According to my Kill-a-watt clone the board idled at 12W w/o an HDD. The guys at silentpcreview measued 11-12W in idle with this board and a laptop hdd using a Seasonic SMPS adapter. According to the manufacturer that HDD consumes 0.6W in low-power idle mode (or 1.9W while read/write). Either way the difference is pretty negligible.

Hey now, lets all remember that home projects do not have to be justified like projects in industry. If he want to build a power supply for the experience, then let him.

Of course buying a COTS component is always preferred, but that is not the point of this website.

Ok…. I’m stepping off my soap box

Power factor? Harmonic distortion? Conducted emissions / immunity? Radiated emissions / immunity? How does it handle fast transients?

Wow after all that work and it’s still a fail on the objective. I guess it was a good learning experience and a fun hobby project.. Kind of like my 120 watt FM transmitter linear amplifier and notch filter cans… Cant use them legally but it was fun blasting the local rap station out of the water with country music for an hour.

Atom motherboard + green PS = dual core server that idles at 8 watts and peaks at 21-25 watts. 4 green WD drives deliver 6TB of storage and spin down when not needed. It peaks at 120watts when I get it to ramp up to full load and spin up all the drives at once but that peak lasts only 30 seconds before it settles back to the 21-25 watts.

The second one I built for zoneminder hovers at 62 watts simply because the 8 chip 120fps bttv card sucks power like no other and zoneminder doing frame analysis is very cpu intensive. But then I have a government class 8 channel video security system that even the $30,000 systems suck compared to it in useability and features.

Basement 19″ rack went from 3400 watts down to under 240. The whole house audio system still peaks at 1000 watts if I have the garage, living room and basement all cranking along, and I cant reduce the 120 watts that the Crestron procesor uses.

Wow, why all the negative vibes in the comments?

Viktor: Congrats on a finished, working project that didn’t cost an arm and a leg :)

Kudos to Viktor for building a working power supply, and for taking the time to write up the details so that others might learn.

But shame to Hack-A-Day. Not for featuring this project, but for falsely representing it as smaller, more efficient, and something other people might want to replicate exactly. For the cost of the parts (or resale price if you already have them) you could buy a PS that really is smaller, more efficient, and more versatile.

Or better yet, you could use recent “hacks” to power the server from free energy, gathered by homegrown piezo crystals, and rectified by toothpaste. Make sure to document the entire build process with two terapixel cameras, and release it as a 3D video which can only be viewed with eyelid shutter glasses. ;)

Honestly, there is really no need for this kind of contraptions anymore. Especially if you are interested in power electronics topics there is ample knowledge around on how to build high efficiency AC-DC converters and how to optimize system power consumption. In general, not just for PC power supplies.

What Viktor has done here is, and I don’t mean this offensive, use old technology and use it in an outdated way. Toroid transformers, although well-coupled and relatively low-emission, suffer from high magnetic losses especially at low power. They are probably the *worst* choice for low power supply if used in this way (with a huge low-esr capacitor causing peaked current use and a bad power factor). Transformers also suffer from relatively high static (i.e. primary voltage-induced) losses. And then your PCB quality: you’re talking about reliability of that big capacitor, and subsequently soldering low-quality etched PCB with unstabilized statically indeterminate pins on the dc/dc converter module. And if anything, audiophiles are again the worst place to go search for efficiency, those weird people are still using class A/B amps…

There is SO MUCH knowledge on the internet and it is so easy to come by that it just plain hurts to see people engaging in such designs for all the wrong reasons. And to see them on hackaday.

Almost all major SMPS controller manufacturers have at least exhaustive application notes, and some even have demo boards, of synchrounous-rectified quasiresonant or LLC resonant switchmode power supplies that can, with a minimum of tinkering or if you are so inclined simulation, attain 90% efficiency or better at these low loads. What is more, you can build such a device either from scratch or by modding a demo board for probably the same money as this device. With input and output protection.

@Shadyman
HaD represents themselves as a place that links to other people’s “hacks”, and does a little write-up on them as well. This is a tiny little bit of work to just link to someone else’s project. It isn’t that hard. Therefore, it is surprising to see oversight like this on almost a daily basis. Futhermore, it is surprising to see poor solutions to a problem (like this) published as relevant “hacks” on a daily basis. I can not imagine how many people are misled by this site every day. HaD needs new management.

“But I’ve never tested the board with a regular ATX PSU so I can’t really say how much of a difference there is.”

@Viktor: Can you do it now? For science sake. If you were right, you can tell all the critics to put a sock in it, and in any case the rest of us will know if we should follow your example or not, or in other words we’ll all gain an insight in how SMPS’s scale their efficiency against power consumption.

Nice project. Some people don’t understand the joy of building things yourself. Yes it can cost more than an off the shelf product but you don’t learn anything do it that way. You can read all the books you want but until you build things yourself you will never understand electronics.

I will be glad when power supplies in pc switch to using one voltage. There is no need for all the different voltages we have now, it is a legacy thing. Nothing is powered directly from 5V or 12V in the pc except the 12V fans. Everything takes the 5v or 12v and converts it to 3.3, 1.8, 1.3 or lower. A single 12VDC supply could power everything in the pc and some things can already do it.

Some hard drives have converters that while wired to 5V on the connector are within specs that would allow them to run off 12V only without anything but a soldering iron modification. Even external devices like routers and modems don’t use 5v or 12v internally. All these devices convert it to lesser voltages. I repaired a router the other day that actually had stamped on the board, DC input 5~18VDC for the input because it connected directly to a smps supply that output 3.3vdc.