A buck converter is a voltage regulator, but more efficient then the linear voltage regulator.

Wikipedia about buck converters:

A buck converter (step-down converter) is a DC-to-DC power converter which steps down voltage (while stepping up current) from its input (supply) to its output (load).

A buck converter is a “switching regulator”, turning the power on and off quickly all the time, compared to the linear voltage regulator which dissipates the excess power as heat.

A very small adjustable buck converter from Ali Express

I bought this 5-pack of very small buck converters from Ali Express and have just received and tried them.

They come preconfigured with adjustable voltage, by turning a small screw on the top. One can also fix the voltage level at 1.8, 2.5, 3.3, 5, 9 or 12 volts by soldering a little on the backside.


There are four connections on this buck converter.

  • VO+ Regulated voltage output
  • GND Ground
  • IN+ DC 4.5-24V (according to Ali listing)
  • EN Enable (I have not tried this one. The converter works without it.)

Fixate the voltage level

Please see the photo below to understand how to permanently fixate the voltage level.

  1. Remove the leading “bridge” at the ADJ mark.
  2. Solder a connection at the desired voltage level mark.

Now you have a stable voltage level coming out from the VO+ connection.