A while ago I decided I needed a way of powering on my small breadboard projects so I looked around the web. In my opinion bench power supplies are actually decent in price. You can buy a bench power supply from China for about $40-$50 and it’s probably more than what you need. Obviously you can buy more expensive ones from different companies that come with more power, more features and some safety features but for $50 the cheap ones from China do the job just right. Again this is only my opinion. I mean after all even the cheap ones are more safe than what I built.

So I decided to build a very cheap one with stuff I had laying around. I found an Instructables post from a known youtuber and I decided to build one like that. The reason was simple, it didn’t require too many components and I didn’t have to build anything from zero. What I needed was an old computer power supply that I had laying around, some LEDs, a switch, one power resistor, binding posts and tools to drill, glue, solder and screw things together. Now the finished product isn’t the best looking power supply out there and if you want to build one yourself you can definitely design a bigger and better case for it, have some boost/buck converter added so you can set a constant current and voltage and so on. A better option and a good idea of what you can accomplish by building your own bench power supply can be seen here.

Building it is definitely fun. Besides the fact that it’s a good soldering practice in case you want to work on your soldering skills it also helps you understand a bit more about your computer power supply and the way it works. It’s actually quite fun to turn it on for the first time. Now a few things I ran into while building it that you should be aware of:

Don’t cut the wires before you open up the supply and decide the positioning of the binding posts. You might cut them too short. Don’t use cheap solder. It’s really a pain to solder stuff together when it won’t even melt. Make sure there are no exposed wires in the end. Make sure the power supply is perfectly functional. (it turns on, the voltages should be correct on all the rails)

A computer power supply can deliver way more current than your regular bench power supply so every time you use one you should make sure you don’t short anything. Another reason why this is not the best is the noise. The supply does get quite noisy but I assume that depends on the quality of your supply in the first place.

In the end, if you have an ATX power supply around, you should definitely try and build one. I need to mention that you would be working with mains voltage and you need to take extra care. Such supplies have big capacitors inside so after unplugging it make sure you either wait for them to discharge or discharge them yourself with a resistor otherwise things can get dangerous. However, it is definitely a nice experience, it’s really cheap and you can only learn from building one!