The idea with this article is to show you how I made my bench power supply. All from components off of Aliexpress and other sites. I have had plans for a bench power supply for a long time, including the possible usage of an ATX computer unit.

What gave me the necessary spark to start this project was that I found a DSN6000AUD buck converter module in my things.

I then designed the entire power supply around it. I also had in hand one of these cheap Chinese volt and ampere (10A) meter. The one in the picture below.

I decided also to throw two more voltages in the mix: a fixed 5V and a fixed 3.3V, as seen in the complete schematic below.

Circuit explanation

The main and first component of this power supply is a 12V/5A unit, similar to those used in laptop computers. It is insulated from the mains, a must in this project; gives the user (me) safety. The 12V from it is used in two places: in a buck converter to generate 5V for the Arduino and in the DSN6000AUD high power buck conveter.

Said converter has an onboard potentiometer which will be exchanged by a bigger one, to be put in the front panel. This variable voltage is then put to use in an output, after being fed to the volt/ampere meter. There are also two identical 3A buck converters, one for generating 5V and the other 3.3V.

They get their voltage straight from the 12V/5A point. Their output will be monitored by the Arduino, both voltages and currents will be read. The current is obtained by a pair of ACS712 hall current sensors. The voltages pass by a 741 opamp with (almost) unit gain.

The two voltages and currents will then be shown in a 16×2 LCD display controlled by the Arduino.

Summarizing the specs

Things there will be in this power supply:

• 4.5-11.5V 3A variable power supply circuit
• Display for monitoring variable power supply
• Fixed 5V 3A circuit
• Fixed 3.3V 3A circuit
• Maybe a fixed 12V/5A out (will see)
• Arduino and LCD display to monitor voltages and currents

I am not planning on addind any fuses to the project, since I will not be handling high power on a daily basis and also every buck converter preset is already electronically protected. Most power converter circuits these days will happily work under short circuit conditions.

This bench power supply is a work in progress, while this message is still here the unit will not have been finished. I will keep you updated.