Homemade Adjustable Breadboard Power Supply

I just finished making a breadboard power supply and decided to share it with the world. I decided to make one when trying to reset the fuses on an ATtiny as discussed HERE. I needed a 12V supply, and the 12V wall wart I was planning on using read 18V.

Full disclosure, I got the idea for this project from THIS Instructable. Furthermore, breadboard power supplies can be purchased for less than $10 on Ebay. Adafruit also sells kits. If you just want a 5V or 3.3V power supply those are even cheaper. Get a $2 MB-102 Power Supply off Ebay. However, if you just enjoy building things or want soldering practice continue reading.

This schematic is really the only reference I used. I found the LM317 in an old computer. The same for the ceramic capacitor (.1uF is one marked 104). I had the other parts. I used a cheap 10k pot I had sitting around and a 220 ohm resistor instead of the ones shown. Be sure you put the polarized capacitor in correctly and mind how you connect the potentiometer, and it's a piece of cake. I didn't use a heat sink but feel free to put one on if you anticipate pulling a lot of current.

Below are some pictures to give you some ideas.

As you can see, the power supply plugs right into the rails of my MB-102 breadboard. Double connections keep it plugged in nicely and the screw terminal allows me to plug in any DC wall wart I want or attach a barrel jack if I need to. Turning the 10k pot adjusts the output from 0V to the voltage of the input.

My mini voltmeter seemed to fit nicely, so I taped it onto a blank space.

That's about it. Now go make your own supply to power all the breadboards in your life.

-Matthew