ATX Bench Power Supply - Convert a Computer Power Supply

@derek

How did you design this power supply?

Which software did you use? Looks good. 😀 

@robotbuilder

Just never heard it referrer to as a SMPS.   Seems like I just remember calling them switching power supplies.

@sumanta

So yes the ATX power supply is a switching power supply.  It is in a particular form with the proper connectors for a PC motherboard.  The purpose of the video was  to demonstrate how you could modify an existing ATX power supply into a bench power supply, which will of course still be a switching power supply.

You can of course buy many switching supplies with either 24, 12, 5, or other voltages.  This is just a example of a project repurposing something you may just have laying around.

Posted by: @codecage

So yes the ATX power supply is a switching power supply.

@codecage

Thanks for the reply. 😀 

@sumanta

I actually used OnShape: https://www.onshape.com/en/

@derek

Thanks for the reply 😀 

A couple of questions and one minor issue (but still worth reporting) -

So Questions First -

1. I have always wondered why these wires from this ATX power supply are paired? I mean, there are two wires into each pin and I never could find out why. Okay, I have assembled a lot of PCs (desktops?) but never questioned this - as I always believed that if you know to ride a bicycle, all you need to know is to ride. But with age, I realize that it is good to know some repairs as well.

2. The Video shows 3 wire sets being used for each pin out. So again, why is that? I mean, if they (the manufacturers) ship with 2 wires going together, why do we need to change that and opt for 3 wire sets instead.

3. Which wire ends were trimmed off from the inside the Power Supply - there was a mention on the video, but I could not figure out which ones. (this is just a minor problem because I understand the wires that are cut are eventually removed and so the other needed Sets should remain).

The minor issue -

The link to the PDF at the moment, does not work. Not sure what that PDF has/had on it, but it might be good with some sketches (non related to Arduino Codes but as in Images/Diagrams).

Parts List is not detailed out (reasons explained on one of the replies here from Bill on earlier pages), but still if someone would help me know what those terms for components are, I might look out at alternatives if I cannot find them locally.

Posted by: @sid

A couple of questions and one minor issue (but still worth reporting) -

So Questions First -

1. I have always wondered why these wires from this ATX power supply are paired? I mean, there are two wires into each pin and I never could find out why. Okay, I have assembled a lot of PCs (desktops?) but never questioned this - as I always believed that if you know to ride a bicycle, all you need to know is to ride. But with age, I realize that it is good to know some repairs as well.

2. The Video shows 3 wire sets being used for each pin out. So again, why is that? I mean, if they (the manufacturers) ship with 2 wires going together, why do we need to change that and opt for 3 wire sets instead.

There are basically two things going on with paired connections.

1) The ATX specification requires sense lines on some of the supply lines. If you see a thick and thin wire attached to the same pin, the thin wire is almost certainly the sense line. Sometimes it's easier for the manufacturer to just use the same guage of wire for both. If you measure resistance across the two and you get something that is not essentially 0, you're looking at a sense wire.

2) The other reason for using multiple wires is simply current/safety. Common ATX power supplies are capable of generating absurd levels of current for what most of us do on the benchtop. If you have a wire-fraying issue and lose one of your wires, with a second wire you're less likely to have a small space heater/firestarter appearing suddenly in your computer case.

I suspect Bill combined wires out of a combination of safety considerations and "why not"? As long as they're all on the same power rail (feedback circuit), there's no issue joining them.

3. Which wire ends were trimmed off from the inside the Power Supply - there was a mention on the video, but I could not figure out which ones. (this is just a minor problem because I understand the wires that are cut are eventually removed and so the other needed Sets should remain).

I would recommend a slightly different approach.

Buy and chop up one of these, and just zip-tie the PSU cables neatly. I would particularly recommend this approach if you're having any difficulties with mapping which wires do what. I very much regret not taking this approach when I built mine. ( https://forum.dronebotworkshop.com/show-tell/an-atx-based-power-supply/)

Parts List is not detailed out (reasons explained on one of the replies here from Bill on earlier pages), but still if someone would help me know what those terms for components are, I might look out at alternatives if I cannot find them locally.

I live in an "electronics supply store desert" and therefore get all my parts online... I forget that some people are lucky enough that getting things locally is an option. 🙂

Regardless, which parts are you referring to specifically?