Lab Bench Power Supply from ATX Power Supply - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: March 15, 2012, 03:22:10 am
content: I just recently finished a project where I took a ATX power supply from my buddy's computer. Its a real simple project that I recommend for any one to try out. all you need is an ATX power supply, a few banana plugs or binding posts, a dummy load, and a couple of switches.This is the one I made.<iframe width="420" height="315" src="https://www.youtube.com/embed/aul9IcuGV84" frameborder="0" allowfullscreen></iframe>this is where I saw it first.<iframe width="420" height="315" src="https://www.youtube.com/embed/aul9IcuGV84" frameborder="0" allowfullscreen></iframe>

author: Spawn
author_rank: Frequent Contributor
timestamp: March 15, 2012, 04:47:27 am
content: These things are very popular, a lot people make them.But here comes the down side, as electronics hobbyist its just pretty close to useless. You can’t limit anything and you have only couple ranges voltage. The current on these things is way too high and since you can’t adjust it, you better don’t try on one of your projects a small mistake and you blow up something.If you need it for something else that is another story.Check Ebay for some bench power supplies, the china models are pretty cheap and you can set your voltage and current. There are a lot different models from 1A till 10A, 2 or 3 ampere should be enough for electronics projects.

author: sacherjj
author_rank: Frequent Contributor
timestamp: March 15, 2012, 04:42:12 pm
content: Also, from what I've seen, you have to add a TON of filtering to get it close to usable for sensitive stuff. This is less of an issue with more expensive power supplies, but most do this to save money and have crappy supplies to start with.

author: dropolus
author_rank: Newbie
timestamp: March 18, 2012, 04:01:25 pm
content: I finished mine a few days ago... it cost me around 20€

author: sonicj
author_rank: Frequent Contributor
timestamp: March 19, 2012, 10:52:51 pm
content: i couldn't live without a high current 12V power supply...i just built one for a friend. added a high current iPhone charge port thats available even if the rest of the supply is off. fun lil project and super useful when coupled with a good hobby charger.if you plan on using for electronics design and prototyping, fuse the output. certainly not the same as a current limiting supply, but better than nothing!-sj

author: T4P
author_rank: Super Contributor
timestamp: March 20, 2012, 08:38:24 am
content: It's only good if your bench supply doesn't have enough juiceThe only spare ATX PSU i have is a puny 200W that requires a fan from a long time ago

author: Unknown
author_rank: Unknown
timestamp: March 23, 2012, 11:50:28 pm
content: Quote from: sonicj on March 19, 2012, 10:52:51 pmActually I was planning on doing that but I found that some atx power supplies have an intelligent breaker in it. If to much current is drawn the circuit breaks and to reset it you just turn the load switch off and back on. One I had actually had this functionality built in. I did not think that it would be in there but it was.

author: stl
author_rank: Contributor
timestamp: March 28, 2012, 11:51:05 am
content: Quote from: MikeJuszkie on March 23, 2012, 11:50:28 pmThe problem is that for the ATX PS too much could be up to 18A or even more, imagine the things you can damage with that current.

author: T4P
author_rank: Super Contributor
timestamp: March 28, 2012, 07:30:43 pm
content: Quote from: stl on March 28, 2012, 11:51:05 amCertainly adding a external polyfuse is a better idea than relying on the internal fuse .

author: Unknown
author_rank: Unknown
timestamp: March 28, 2012, 07:35:57 pm
content: Quote from: stl on March 28, 2012, 11:51:05 amExactly. How will those ESD diodes and bond wires behave if you reverse power and pump 10A through the power pins?Polyfuses have two disadvantages for this application: their response time degrades when they trip, so they will be even slower the next time around. They will also still allow some current to flow, unlike real fuses, which may not be desirable in a fault situation, depending on thevalue of 'some'.

author: Spawn
author_rank: Frequent Contributor
timestamp: March 28, 2012, 07:52:15 pm
content: 18A or more is only for the 12V side, check the chart on my old Enermax box i had laying around, the 3.3V and 5V is just too high:I got the 470W, just sitting in a box for some reason i never used it.

author: Unknown
author_rank: Unknown
timestamp: March 28, 2012, 08:33:05 pm
content: Don't forget the large bank of low-ESR capacitors ready to dump their charge into your circuit.

author: george graves
author_rank: Super Contributor
timestamp: March 28, 2012, 11:47:22 pm
content: ATX PS...pfff...It's not worth the cost of the banana jacks. You're better off building a lm317 breadboard supply.

author: muvideo
author_rank: Frequent Contributor
timestamp: March 29, 2012, 08:56:18 am
content: Making CV/CC psu from atx power supply is not that hard, if you search for the ones (usually old)that use a TL494 or KA7500 or clone as regulation ic.Like many have pointed for lab work the psu is nearly useless, and the time spentfor making it function properly is not worth, the noise is huge, the regulation approximate,the out capacitors are killers. Only if you have the need for high current into something,but going past 10A isn't all that easy if you plan to use it in Constant Current regulation.It's only an excellent learning excercise.This is an example of what to do:http://www.chirio.com/switching_power_supply_atx.htmit's in italian but i think you can find something also in english.I made some psu from ATX, now they are used by a friend of mine for charging Pb batteriesand making some aluminium anodization.For my home lab I bought a pair of linear 5A/30V and a pair of used hp 6632 forautomated things, these are great because can be used also as electronic load.After all a 5A/30V linear is 50€ on ebay (I paid 90€ for two Long Wey) and apartthe funny name they are working reasonably ok.Fabio.