Tuesday, January 7, 2014

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.

1 comment:

  1. That breadboard power supply is an interesting project, as you can build alternative, adjustable circuits for small devices and future projects. But of course, it is necessary to take precautions, just to be safe. Thanks for sharing!

    Kelley Burton @ Aim Dynamics