DIY Power Supply !

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About: Hi, I'm Nemeen, Electronics Enthusiast! I have seen a huge decline in electronics hobbyist in past few years. I started this channel in order to inspire you to create. Hopefully, you will find something tha...

I recently found an ATX Power Supply which offers a quite a decent power at its output. But most importantly it offers +12v, +5V, and +3.3V at its output which is very commonly used in electronics so let's turn this into a Lab Bench Power Supply!

Warning: If you have No idea about electronics then don't try this, AC Mains Voltage is fatal! especially with high voltage capacitor.

Step 1: Watch the Video !

if you don't want to read all the stuff you can watch my video on youtube

Step 2: Disassembly and Testing

Before you start opening the case of ATX power supply first keep the power supply unplugged to discharge those high voltage capacitors.

Then open the case of ATX power supply and clean the internal electronics with a brush or blower.

Now we first need to check if the power supply is in working condition. To check that take 20-24pin connector and connect 14th pin i.e Green color wire to any of Black color wire Pin. If power supply's fan starts then it is in working condition.

Step 3: Trimming and Sorting

Now you can trim down the wires to an appropriate length because we don't need connectors. Once done Sort the wires according to color.

Red is +5 V

Yellow is +12V

Orange is +3.3V (Brown wire is voltage sense for 3.3V so connect it with orange)

Blue is -12V

White is -5V

Green is PSU On

I dont need -5V and -12V so I wont be using them.

Step 4: Drilling and Soldering !

Now drill holes for banana Connectors (Binding post) and attach them, Make sure they are tight or else they can short something in future.

Now strip all the wires and solder them in a group according to their colour. Now solder the entire bunch to the binding posts. Make sure to leave 2 Black wires,1 Red and 1 Green wire.

Step 5: Adding Dummy Load

To make sure our Power supply output is stable we need to add a dummy load, add a 5 Ohm 10w resistor to it. I don't have a 10W so I'm using two 10 Ohm 5W in parallel. Now solder Red and Black Wire across it. Don't forget to cover it with some tape, and place the resistor in the power supply case.

Now the only thing left to do is connect Green wire to Black wire so our power Supply is Always ON. You can add a Switch otherwise.

Step 6: Done !

That's it! You did it just plug it in mains and check the Output!

If you like my work

Feel free to check out my YouTube channel for more awesome stuff: https://www.youtube.com/c/Nematics_lab

You can also follow me on Facebook, Twitter etc for upcoming projects

https://www.facebook.com/NematicsLab/

https://www.instagram.com/nematic_yt/

https://twitter.com/Nematic_YT

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15 Discussions

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Gelfling6

2 months ago

Usually most of the newer supplies won't require the dummy load, but 5=ohm? seems a wee low.. I built one, using a 33-ohm 5W sandblock and it runs fine. all of the older supplies (no 3.3V) required this load but most modern (with 3.3V) already have some form of load. on the board itself inside

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hardwaylearn

2 months ago

To anyone who makes batt charger if charging flatter batt use headlight globe in series to limit current, or could burn out supply. Don,t ask! Eg 12v batt, use 12v halogen bulb in pos line(100W). Globe will glow dimly till current drops then go out- can then bypass globe.

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mekertventifact

Reply 2 months ago

Does it really matter!??
He’s labelled each terminal clearly, and there will only be him using it!
The only thing that is important is that he’s worked safely, and he’s made the PSU safe to use.
If you can save money on the binding posts then it’s a cheaper project, and still completely safe to use.

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Nematic!ventifact

Reply 2 months ago

I had to buy them in pair so just saved few bucks there :p

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Kalebs-how2s

2 months ago

also if you connect the green wire to one of the black wires the fan will start spinning. I have just started making one of these and I didn't know what to use but now i seen you used banana clips so thanks.

1 reply
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hardwaylearn

2 months ago

These make top battery charger, just increase feedback resistor to regulator ic to get 14v ,7v, 13.4v out, add ammeter. Switch off before changing volts out.

1 reply
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Nematic!hardwaylearn

Reply 2 months ago

definitely can be done but working around such ATX supplies for beginners is not a good idea becaues of capacitors

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rogermari

2 months ago

Thanks, Very useful and easy to follow guide

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gm280

2 months ago

So many hobbyist have used the ATX type power supplies to build a bench top power supply. And for good reason, they are pretty good at supplying +12 volts and +5 volts and even +3.3 volts at pretty substantial currents. But you also need a variable output for higher voltage supplies. I always build my supplies with at least 24 volts or high for the odd electronic circuits. Add a LM317 or similar variable voltage circuit into your supply and you will love it. There are so many times I need a higher voltge as well as +12 and/or +5 at the same time. And a variable is great for testing relay drop out voltages and such. Just a suggestion. But you posted a great PS project all the Same. Here is my last one I made...

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charles543gm280

Reply 2 months ago

An LM317 powered by 12V will only give you 10.5V. You need voltage 1.5V higher than your desired voltage (25.5V for 24V). A digital boost converter might be the way to go.

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billbillt

2 months ago

i have made plenty of these from atx supplies.. i can vouch for them....

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russ_hensel

2 months ago

Welcome to the club: Just a note to let you know I have added this instructable to the collection:

Encyclopedia of ATX to Bench Power Supply Conversion

>> https://www.instructables.com/id/Encyclopedia-of-A...

Take a look at about 70 different approaches to this project. This topic is one of the more popular of all instructables.

1 reply
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lrdruss_hensel

Reply 2 months ago

Have you thought about opening a "collection" to weather station or weather monitor too?