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ATX Power Supply - the elegant way to adapt to benchtop use...by jordanyte on April 23, 2010

Table of Contents

ATX Power Supply - the elegant way to adapt to benchtop use... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Intro:   ATX Power Supply - the elegant way to adapt to benchtop use... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 1:   Acquire the ATX PSU Benchtop Adapter PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 2:   Get a handful of cheap parts to solder on to the PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 3:   Connect your ATX supply and try it out! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

http://www.instructables.com/id/ATX-Power-Supply-the-elegant-way-to-adapt-to-ben/

Intro:  ATX Power Supply - the elegant way to adapt to benchtop use... If you want to use an ATX power supply as a benchtop unit, without hacking it to pieces or risking fire and electrocution, then this approach is definitely for you. 

NEWS: due to increasing inquiries I have made this item in to a complete kit. Let me know if you or your college / lab are interested. Full schematics BOM and assemblydocs are provided too. 

Image Notes1. This green version was the earlier short-run prototype. The current version isblack with gold finish on the copper.

Step 1: Acquire the ATX PSU Benchtop Adapter PCB This PCB has been specifically designed for this purpose, and is layed out for access to all the ATX supply votlage rails, even the standby supply and the "power good"signal. This PCB can be acquired from http://www.jordandsp.com/index.php?p=1_2_Projects . Since there was enough interest in using it, I had quite a few manufacturedto get the price down.

Image Notes1. Note the 20-pin ATX header footprint, which includes holes for mounting posts.2. These plated-thru slots are for use with alligator clips - but always remember to clip BEFORE switching on the supply.

Step 2: Get a handful of cheap parts to solder on to the PCB I found the parts were easiest to get all of them from Jameco Electronics: www.jameco.com - but you could get them from Digi-Key, Newark or Mouser. I'm not sure whoelse stocks the Molex connector used for ATX motherboards, but Jameco have them at a low price.

You can see on the final step images the 4049 hex inverter, four resistors and several capacitors are on the front side of the board. On the back here you can see thebinding posts just poke through their respective holes and you tighten up the nuts on the back, giving good electrical and mechanical connection. 

The Molex-style connector (ATX header) is mounted on the BACK of the PCB. The new (black) version of the PCB is keyed with the connector so you can't install it thewrong way. PAY ATTENTION - There is in fact a silk-screen on the bottom of the PCB as a guide. Once you are ABSOLUTELY SURE you have it in the right position (asshown here), solder it in place from the FRONT SIDE of the PCB.

Before you solder any other parts on the board, you may wish to enhance the current-carrying capacity of the main voltage rails - you can do this by adding solder tothem where there is an opening in the solder mask which you can see in this picture. This is optional - or course.

http://www.instructables.com/id/ATX-Power-Supply-the-elegant-way-to-adapt-to-ben/

Step 3: Connect your ATX supply and try it out! Simple as that! No drilling, metalwork, etc. and best of all you have access to ALL the supply's outputs. 

The binding posts are also banana sockets as you can see here, so they fit in well with a breadboarding setup and other lab gear, like my Metex meter in the background:-)

Now optionally, you can mount this in a box using the four holes market MNT1 to MNT4, but the binding posts I used have a front panel mounting nut as well - visible inthis photo - which stands away from the front of the PCB. Since there are ten of them, they will provide a very strong mounting mechanism (when I get around tomounting this in a box that is!).

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http://www.instructables.com/id/ATX-Power-Supply-the-elegant-way-to-adapt-to-ben/

Comments

19 comments Add Comment

 darthneo says:  Sep 28, 2010. 12:50 PM  REPLYCan i ask where you got the banana posts?

They seem quite expensive on electronics websites (digikey, mouser, jameco)Ebay has 5 (5 different colors) for 5.30$, i wouldn't expect these to be so expensive...

 jordanyte says:  Jan 26, 2011. 6:07 AM  REPLYI have solved the banana post problem. Yes you are right in small quantities banana posts are quite expensive.

So... after getting lots of PCBs made, I also went ahead and bought enough parts - banana posts included, (the color coded ones as shown) - to populatethem all.

So now I can provide a complete kit for you. This kit with the board and all the parts is cheaper than if you went to Jameco or others and bought them all.

 darthneo says:  Jan 26, 2011. 12:29 PM  REPLYOh, thats cool! i have put all my electronic projects on hold because of college and work, but i ended up getting, i think, 12 banana posts for 10$ offebay.

Out of curiosity how much are you selling the complete kit for?

 jordanyte says:  Feb 10, 2011. 4:17 AM  REPLYI have put together complete kits for $30USD plus shipping. I will offer discounts for bulk orders (i.e. school labs).

 merlinmalone says:  Jan 18, 2011. 2:50 AM  REPLYNice little project. As an electronic engineer I was planning to do the same, then came across your design. A couple of questions:

1. What are the outputs rated at (without adding solder to the traces)?2. Do you have problems with the nuts on the posts shorting out between the copper planes on the PCB? In the pictures on your website they seem tooverlap in places - maybe if you do another version increase the space around the terminals.

As a suggestion, rather than putting it in a box it might be nice just to have a sheet metal 'L' shape made up which you can bolt both your board and the ATXsupply to - it doesn't really matter that it's open and makes it a neat unit.

Also, not sure that adding vias around the holes "offer increased strength for tightening up screws over" - removing material decreases strength, but it looksnice :)

 jordanyte says:  Jan 18, 2011. 3:34 AM  REPLY1. The 5V rail would easily handle 40+ amps. The others a similar however the -12V rail had narrower traces, simply because a typical ATX supplycannot provide more than a few amps on that rail. I would say the PCB can handle more current there than most supplies could give.

2. The post mounts are specifically designed for the binding posts used. I have these available in a kit form. You *might* be able to use other posts butthe ones I specified in the design will NEVER have ANY problems shorting to ANYTHING.

As you say, it would be nice to mount the PCB directly on a bracket on the benchtop. Well, if you look closely at the alligator clip slots I included - thismakes perfect sense and is in fact just how it's intended to be used. But there's no reason not to put it in a box if you would prefer either _ I just wanted itto be flexible. Great minds think alike :-)

As for the vias - well, the *real* reason they are there is to lower the connection impedance to the binding posts - not that it would make a hugedifference, but it feels good having them there ;-)

Thanks for checking it out!

 merlinmalone says:  Jan 18, 2011. 4:03 AM  REPLYI don't think you'd want to draw 40A on the 12V (down two wires) - you might release the 'brown' smell. :)

Looking at the image on your site: http://www.jordandsp.com/images/board_and_multimeter.jpg the nut under the yellow terminal in particular lookslike it overlaps the plane gap. Maybe the chamfer on the nut is enough to clear it though.

I personally probably wouldn't use the croc clip points (nice feature for many though) and would mount the board on the back of a metal panel usingthe terminals. Depending on the length of terminal you use you should be able to clear the components on the board, maybe need some stand-offson the mounting holes..

A good source for the 4mm terminals is Farnell if you have one in your country. Links to the relevant UK parts:http://uk.farnell.com/jsp/search/results.jsp?N=1011020+401&Ns=PRICE_PLS_006_PRICE1|0

http://www.instructables.com/id/ATX-Power-Supply-the-elegant-way-to-adapt-to-ben/

 jordanyte says:  Jan 18, 2011. 5:29 AM  REPLYDefinitely.

The binding posts shown in the images have insulated nut/washer on the front side of the board, so if you are mounting on a panel the bindingposts will probably be all you need for a secure mounting (after all there are ten of them :-))

Also, these posts when mounted allow all the other components to clear the panel. When I did the PCB design I did a full 3D mechanical modelalso to make sure this would work.

The other good thing another person pointed out is that you also have the solder pins available behind the posts on the rear side - which heintended to use to solder on a 20W "minimum load" resistor (though all the supplies I have used with it did not require a minimum load - theyregulated well just with the internal fan - but not all PSUs can do that, particularly older ones).

 merlinmalone says:  Jan 18, 2011. 2:54 AM  REPLYAlso, to increase the current capacity of the +12V rail (as it's only 2 pins on the ATX connector) you could add sockets for one or more of the disk driveconnectors.

 alfa2red says:  Jan 4, 2011. 5:15 PM  REPLYYou done some thinks nice. But if all the part was installed inside like the first project has done years ago it look better.

 Chestum says:  Sep 28, 2010. 3:51 PM  REPLYgreat work, looks great. sent ya an e-mail ( Curtis )

 jordanyte says:  Sep 3, 2010. 5:07 AM  REPLYHi Everyone, Since the first short run all found new homes, and I am still getting inquiries about the board, I have taken the plunge and had a large batch ofthem made. There are three of major benefits - 1) I was able to implement some minor changes and improve the function of the board. Particularly the ATXconnectors available at low-cost from Jameco (or the more expensive Molex ones from DigiKey) which are 20-pin connectors, fit perfectly with an updatedPCB footprint. 2) The switching functions have been labelled in the silkscreen, and I also made the main on-off LED indicator bi-color: green for Standby andred for On. The other LED is the "no-Power Good" indicator so flashes on at the beginning and goes off when the rails have settled. If it stays on it means thePSU has a fault. 3) They are a lot cheaper to make because I made a lot of the new boards. Let me know if you want one or two (or a bunch for a universitylab) and I'll send you the details. I chose not to swap the connector location with the mounting holes as the intent was always to mount the board on anglebrackets hanging from a shelf above my workbench, or mounted from a front-panel of an enclosure. I also decided to go for an electroless gold finish (harderto solder, but better for the environment etc. etc. and besides, it just looks better ;-) ), and black solder mask. See the updated image. Also, I'll soon post ashort youtube video showing how it functions - stay tuned.

 The Ideanator says:  May 1, 2010. 10:05 AM  REPLYThis is a lovely idea, but for $20, I'd want a nice little acrylic case that can be attached to the psu box with minimal effort (some drilling isnt bad)Here's a suggestion for revision 2, on the connector side of the board, flip where the holes and connectors are so one could easily mount it on the psu withstandoffs (that you might throw in to a kit)

http://www.instructables.com/id/ATX-Power-Supply-the-elegant-way-to-adapt-to-ben/

 jordanyte says:  May 4, 2010. 4:15 AM  REPLYThanks for the feedback!

 frollard says:  Apr 24, 2010. 10:51 AM  REPLYThat's really cool!  How would you feel about open sourcing the schematic for the DIY among us?

 The Ideanator says:  May 1, 2010. 9:49 AM  REPLYDon't forget the pcb images.

 jordanyte says:  Apr 26, 2010. 8:14 PM  REPLY Hi All who are interested:

I have put the schematics and assembly drawing at the following location:www.jordandsp.com/web_images/atx_psu_adapter.pdf  

This design is simple - anyone could have done it. Even so, it's (C) copyrighted ownership of Benjamin Jordan.

Feel free to make your own, but don't copy it and pass it off as your design. Please give credit where it's due.

And, for those who are interested I have a few PCBs still, and will make more if more people want one. Please email me ben [at] jordandsp [dot] com if youwould like one.

 frollard says:  Apr 24, 2010. 10:54 AM  REPLYOop:  double post...

How does this circuit deal with the required load on the 5v line?  My understanding is the supply will start cooking itself if it doesnt have any load to regulatefor.

 jordanyte says:  Apr 24, 2010. 10:29 PM  REPLYHi frollard,

I do know some older SMPS (i.e. pre-ATX standard era) were not able to run without a load. I have tested numerous ATX ones and all of those wereokay without it (the fan was enough of a load). I guess there's nothing to stop you adding a load to this via therminals though.

I will post PDFs of the schematic soon - I'm not on the right PC at the moment.... but they're seriously nothing complex. Anyone could do this if they wereso inclined.

BTW I do have a few boards made. If enough folks are interested I'll do another batch.