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Monday, May 18, 2015

Tuning a 0..30V DC 0..3A PSU DIY kit

Before you read on, you should know that after building two versions of the DIY kit, I was not very impressed about the stability, noise, but above all, the complete lack of any form of protection. Think about that before you connect something valuable to the supply.

Subsequently, I designed a more modern power supply that you can follow here:

After building two of them as well, and learning a lot and have a lot of fun experimenting and building, I still decided to purchase a lab quality professional power supply.  That should hopefully tell you a few things. 

There are many things you can learn about the kit in this post, and also select possible improvements, but please understand that I can't really help you anymore. It's been too long ago.

Due to a move, I recently sold my large lab PSU, and needed a substitute. I wanted to be a little more flexible, and did not want a huge and heavy supply on my bench anymore.

Searching the web, I came across an inexpensive DIY kit that implemented a very popular design for a power supply. I seldom if ever need more than 1A, so I used the kit to tune it to my liking, and also added the latest modifications for the original design.

I added an LCD display and one addition to the original design is a current setting mechanism, using the display, so you can set the current limiting or constant current mode before connecting the DUT.

I have built two supplies and can connect them in parallel to get more current, or in series to get a true dual +0..30V *zero* -0..30V supply or a 0..60V supply. One is designed for 3A and one for 1A max.

After some fiddling, I also designed a simple dual tracking system when the two supplies are used in series, so one supply controls the other.

Tuning a 0..30V 0..3A PSU kit

The very popular PSU schematic for a lab power supply that can supply 0..30V and 0..3A ( has created a lot of interest.
So much so, that several Chinese suppliers have created a kit with just about all parts including a PCB for a very attractive price. I paid $12.64 and that is with free shipping. On top of that, it took less than 2 weeks for the kit to arrive.

I purchased this one: