Build yourself a professional bench top power supply

Recently I purchased a ZK-4KX Buck-Boost Convertor from AliExpress for AUD $15. This module takes an input voltage of 5V to 30V and outputs a voltage of 0.5V to 30V. It can work stably at 3A for a long time, and can reach 4A under enhanced heat dissipation. Like any good power supply, you can set the maximum current the circuit you are powering can draw.

Wiring the ZK-4KX module can't really be any simpler. I connected it to a HP power brick from a old discarded laptop. It outputs 18.5V at 6.5A. I was so impressed with the quality of the output of this module that I decided to make it into a desktop power supply.

Preparing the power brick

Using a Dremel with a cutting wheel, open the black case that surrounds the power brick. Carefully remove the board from the case. My board was encased in a tin shield which I removed. Remove any power plug and the output cable.

Building the case

I designed a case to hold the power supply and ZK-4KX Buck-Boost Convertor. The STL files are included. Either take these to a 3D print shop or if you have your own printer, run them through your slicing software. I used a 0.2mm layer height and they need orientating in your slicing software.

On the base, drill out the four PCB mounting holes with a 2.5mm drill and create a thread with a 3mm tap.

The lugs that hold the shells together are a bit fragile. I glued on washers before I drilled the holes with a 2.5mm drill and created a thread with a 3mm tap. Drill out the holes that the screws go through with a 3mm drill.

Assembling the power supply

The base contains a holder that is designed to fit the HP Laptop power supply board. The power supply is hot glued into the holder. The rest of the components are mounted on the front and back panels.

Using the ZK-4KX Buck-Boost Convertor

To set the output voltage:

• Press the U/I button and a digit in the voltage display will flash.
• Press the Rotary Encoder to move the cursor to the next digit.
• Rotate the Rotary Encoder to adjust the voltage.
• Press the U/I button twice to show the output voltage and current.

To set the output maximum current:

• Press the U/I button twice and a digit in the current display will flash.
• Press the Rotary Encoder to move the cursor to the next digit.
• Rotate the Rotary Encoder to adjust the current.
• Press the U/I button to show the output voltage and current.

To switch on/off the output voltage:

• Press the Rotary Encoder to switch on/off the output. The ON light will light up when power is active at the output socket.

Final Thoughts

This is a fantastic module and is a great way to put some of those power bricks that have been salvaged from old lap tops to use. I believe there is a new version out now that incorporates a fan.