Introduction: DIY Modular Bench Power Supply

In this instructable I will explain how to make your own bench power supply from ready-to-use modules.

The specs are:

- Using off-the-shelf modules.

- 24v up to ~3A.

- Has USB charging ports which are isolated from both channels.

- Dual channel.

- Takes AC input.


- Both channels cannot be connected in series.

- USB charging is slow because the transformer used is small, you can hook your own powerful transformer to overcome this.

- It does not offer current limiting capabilities.

With all that out of the way, let's get started!

Step 1: Watch the Video

The video is just 5:30 minutes and describes everything.

Step 2: Tools and Parts Needed

The parts are:

Prototype boards:

Screw terminals:

10K potentiometer:

10K 10-turn potentiometer:

* you can use the 10-turn potentiometer in both channels which is significantly better, but the normal one is cheaper.


Binding posts:

Dual display panel meter:

* you can use any panel meter but make sure of its connections are these differ from each other.

AC-to-DC module:

* this module claims 4-6A output current but I didn't test it to this amount. I suggest using it since it is extremely cheap but if you find you need more current then get another one with 24v output. They are available.

Buck converter module:

LM317 module:

* this one didn't work as intended so I replaced it with another buck module and it performer perfectly. I suggest using the buck module instead of this one.

Instrumentation desktop enclosure:

* I really like this one but if you have another plastic one then go for it, just make sure it fits the components.

Also, get a simple transformer to output 12v or anything as explained in the video... Unless you don't care about isolation, then connect the USB charging circuitry to the AC-to-DC module.

As for the tools, they are mentioned in the video which are nothing special. Just make sure you have a nice soldering station.

Step 3: Theory of Operation

This project is very simple, and here is the explanation.

It takes 220v (or 110v) AC power from your outlet as its input which is connected to the AC-to-DC converter module which turns it to 24v DC.

Then this is fed into 2 DC-to-DC buck converter modules, each one for one channel. Each one has its own potentiometer to adjust the output voltage.

Each channel is attached to a dual display panel meter to show voltage and current.

There is a transformer hooked to a buck module to output 5v to USB ports for charging phones and so on.

Step 4: Making and Assembling

You have to connect the parts together according to how I explained in the video.

Also, make sure to use the hot glue gun to fix everything in its place! I attached enough pictures to further show the operation.

IMPORTANT: please make sure you follow the wiring of the panel meter specifically as I mentioned or you will get LOTS of shorts.

By that the project is complete! let me know your opinion in comments and if you have suggestions.