Any really nice DIY power supply designs out there? - Page 1
Forum section: electronics / projects

author: Helder22
author_rank: Contributor
timestamp: October 09, 2014, 03:27:19 am
content: I was thinking of making my own power supply, mostly as a learning experience, since I already have a real nice Rigol PS. Not that I would not use it after I built it of course.I see lots of designs out there but they are mostly rather simple. I was wondering if there was a design out there with lots of nice features like current limiting, a nice voltage range, displays etc.it doesn't have to be easy. I am looking for a little challenge and a nice high quality PS to show for my work in the end.Anyone know of any?

author: simingx
author_rank: Contributor
timestamp: October 09, 2014, 03:45:16 am
content: I do remember a member here mentioning to look up the schematic/service manual for the HP/Agilent/Keysight E3631A power supply and just ripping out the analog regulator section from the schematics. Nottoocomplicated, a few cheap opamps will do itI don't think I'm supposed to post links to it directly, so Google is your friend O0

author: david77
author_rank: Frequent Contributor
timestamp: October 09, 2014, 04:19:36 am
content: +1 on the HP PSU schematics.There are really good designs in those manuals, especially the older stuff with detailed circuit descriptions are worth a look. Some time ago I was looking to build a small tracking supply but I didn't want to spend weeks rolling my own design, so decided to copy the HP 6236. Works a treat and was relatively easy to clone, nothing fancy though.There's a HP white paper out there that describes all the pro's and con's of the different topologies for linear PSU's - also well worth a read.

author: tombi
author_rank: Regular Contributor
timestamp: October 09, 2014, 05:00:22 am
content: I've been thinking about building something like this too - I have wanted a DP832 for ages but decided I would try and build one instead!Let me preface this with the statement that I develop software for a living (not hardware) and that all of this is just blue-sky idea right now.Some thoughts I had were:1) Use a 'heavy' uC as the controller - something that you can easily get a nice high-res TFT screen for. ideally one with ethernet and/or USB support so you can monitor current usage etc. It would be cool to be able to display a current consumption histogram like the high-end KeySight meters do etc. I was originally thinking a Raspberry PI with a super-cap UPS for this but maybe it would be simpler to just use a biggish Arduino with ethernet shield? Pi has the advantage that if you want to do something custom you could just ssh into it and use write a shell or python script! Maybe touch screen but definitely want a jog dial and a keypad.2) Two channel output. Each channel is a separate module but can be interlinked for tracking dual supply mode3) Use two cheap multi-tap transformers and relays to select the tap. Totally linear design (no tracking pre-regulator). I was thinking of a bigger version of one of thesehttp://www.jaycar.com.au/productView.asp?ID=MM2014&w=transformer&form=KEYWORDOther crazy ideas were to experiment with 3D printing the front panel and even 3D printing a button sheet out of Ninja Flex (my son backed a kickstarter and the printer comes in December/January).

author: zapta
author_rank: Super Contributor
timestamp: October 09, 2014, 05:42:43 am
content: Peter oaks has a series about power supply design. He is very knowledgeable and doesn't try to be cute.Here is part 1 (intro)

author: simingx
author_rank: Contributor
timestamp: October 09, 2014, 06:07:00 am
content: Quote from: tombi on October 09, 2014, 05:00:22 amUnless it's for educational/learning purposes, you'll end up cheaper and possibly more reliable by just buying one, if bells and whistles are what you're after.

author: ketil b
author_rank: Regular Contributor
timestamp: October 09, 2014, 07:13:04 am
content: Quote from: david77 on October 09, 2014, 04:19:36 amHi do you know the name of the white paper, it sounds like a good read.Ketil

author: david77
author_rank: Frequent Contributor
timestamp: October 09, 2014, 07:24:43 am
content: That's the chaphttp://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&ved=0CEoQFjAH&url=http%3A%2F%2Fliterature.cdn.keysight.com%2Flitweb%2Fpdf%2F5952-4020.pdf&ei=pzc2VMyOKYG6ygOJnYJI&usg=AFQjCNGBYLS4VXaWx4EWZriXcvO4oiF6wA&sig2=ZVpuG3TQniZx3qxWsJn6bw&bvm=bv.76943099,d.bGQ&cad=rja

author: tombi
author_rank: Regular Contributor
timestamp: October 09, 2014, 08:57:23 am
content: Quote from: simingx on October 09, 2014, 06:07:00 amIt is pretty much for self-education but if I can get it within 1mV/1mA with decent regulation (DP832A specs basically) then I do have a fair bit of money to play with before I get to the price of a commercial unit.Also most of the bells and whistles I can think of are software which I find easier (and is free).I am presently repairing an old Tektronix 475 (for fun) and I really like the idea of open source tools - without full schematics I could never have repaired this old scope. Also, if there was an OSH PSU with these capabilities I think it would be a more useful.

author: simingx
author_rank: Contributor
timestamp: October 09, 2014, 09:13:10 am
content: Quote from: tombi on October 09, 2014, 08:57:23 amThen you can't go wrong by duplicating the analog part (that's the difficult bit!) of the E3631A and sorting out the rest in software. Everything's voltage controlled and there are nice monitoring points for the voltage and current...

author: ketil b
author_rank: Regular Contributor
timestamp: October 09, 2014, 11:40:08 am
content: Quote from: david77 on October 09, 2014, 07:24:43 amNice, thanks and I'm off to bed for some readingketil

author: Helder22
author_rank: Contributor
timestamp: October 09, 2014, 09:50:17 pm
content: This is some awesome info fellas. I'm watching the Peter Oaks videos right now. Learning a lot!I'm gonna study that Power supply handbook and the schematics for the E3631A next.

author: zapta
author_rank: Super Contributor
timestamp: October 10, 2014, 04:46:19 am
content: There is another thread here about a cute mini power supply from Instructable.

author: diyaudio
author_rank: Frequent Contributor
timestamp: October 10, 2014, 08:23:06 am
content: Quote from: Helder22 on October 09, 2014, 03:27:19 amI would start looking at service manuals from reputable companies example the HP ones and reverse engineer them, rip out the MCU sections and re-purpose the error amp CC, CV analogue sections to your needs, good learning will come from studying proven good designs, it will require a reasonable amount of effort though (would be great if it was a group effort).I must admit most DIY power supplies are just to simple, limited and full of defects only discovered after construction or never even publicly disclosed.

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 10, 2014, 02:00:27 pm
content: Quote from: simingx on October 09, 2014, 06:07:00 amWay cheaper but not near as much fun. I've got more in this than I'll publicly admit but I've actually learned a few things so the trade off might be worth it.Quote from: david77 on October 09, 2014, 07:24:43 amMore user friendly urlhttp://literature.cdn.keysight.com/litweb/pdf/5952-4020.pdfQuote from: diyaudio on October 10, 2014, 08:23:06 amQ2 was added back in here after studying an HP design. I still haven't discovered all of the flaws but I'm working on it. The mosfet delay in the upper left is new and untested but simulates well thanks to help from some members here. I've tested this to a fair degree and can say that it works but I'm not an expert either. I've only loaded it at 30V @ 3A using a resistive load because I haven't built an electronic load yet, that's the next project.

author: Andreas
author_rank: Super Contributor
timestamp: October 12, 2014, 01:54:42 pm
content: Quote from: liquibyte on October 10, 2014, 02:00:27 pmI think the more interesting load would be 3A at near zero Volts. But I guess that only 2*2N3055 cannot handle this without any preregulation.How is the power supply voltage at the TLE2141?I fear that the transformer can deliver up to 50 V in idle (28V*1.4 * 1.1 idle factor * 1.1 line voltage tolerance) after the rectifier which could be too much for the TLE.For a electronic load you will need only a PWM-Generator (NE555) a high current MOSFET and some power resistors.With best regardsAndreas

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 12, 2014, 10:51:12 pm
content: Quote from: Andreas on October 12, 2014, 01:54:42 pmI had planned on testing down to about 5V @ 3A but don't have a load that can do it yet. I've got the 3055's on a huge heatsink with active cooling so until I test it, we'll never really know.I get 43.7V after rectification and filtering.I've often worried about being so close to the tolerance but it seems to be working.

author: void_error
author_rank: Frequent Contributor
timestamp: October 13, 2014, 07:48:04 am
content: Quote from: Andreas on October 12, 2014, 01:54:42 pmI've managed to get around the max. opamp voltage supply issue and used 5V opamps and a discrete gain stage.liquibyteyou might want to take a look at my latest design I posted herehttps://www.eevblog.com/forum/projects/bench-power-supply-design/105/So far it's just been breadboarded and it seems stable with LM324 opamps. I'll have to do more testing after I design a PCB for it.

author: David Hess
author_rank: Super Contributor
timestamp: October 13, 2014, 01:39:57 pm
content: Quote from: simingx on October 09, 2014, 03:45:16 amI would consider doing the same thing with the Tektronix PS503 design but HP power supplies are just as good if not better. I would not copy either exactly though.Quote from: void_error on October 13, 2014, 07:48:04 amI prefer bootstrapping the low voltage operational amplifier's supply but a voltage gain stage is easier to use and understand.

author: liquibyte
author_rank: Frequent Contributor
timestamp: October 13, 2014, 02:42:41 pm
content: Quote from: void_error on October 13, 2014, 07:48:04 amOne of the reasons behind wanting to fix the design I posted, other than the time and money I already have in it, was because so many people stumble upon it and attempt to build it as a first hobby supply. It's a relatively easy looking circuit and has a low enough parts count that they won't pass it by as being too complicated. The truth behind it is that it's not all that great of a design but does get the job done as long as you aren't asking for too much. I've been attempting to fix the issues with it and I've got a hacky solution in place for transient surges that should work. Once I've tested it fully, at least it will be a workable first PS with very little surprise built in.Having said all that, I'll give yours a closer look, thanks. The gain stage is a nice workaround, have you modelled it?