World's Smallest DIY Pocket Power Supply





Introduction: World's Smallest DIY Pocket Power Supply

Power Supply is a fundamental device in any electronics lab . The major downside to them is that they are often bulky and are not very portable. if you want just a variable voltage output with step down voltage these big supplies don't make sense.So, Here I present you World's Smallest DIY Pocket Power Supply.This Supply is so small that it fits any one's pocket and is capable of many functions.

Also Check My blog for more :-

Step 1: Features and Specs

This Pocket Power Supply has Following Features:-

  • LED Display For Displaying voltage output .
  • Output Voltage range from 2.5 v to 30 v.
  • Input Voltage range from 5 v to 35 v.
  • Output Current has high as 2.2 to 2.5 amp.
  • No need of Heat sink.
  • Very small fits in any pocket.
  • Has variable output voltage.
  • Voltage can be adjusted through a potentiometer.
  • Terminal blocks for easy connection.
  • feedback controlled ic

know more about IC here :-

Step 2: Gather Your Parts

Following parts are Required:-

  • LM317T X 1
  • 10uf/63v capacitor X 2
  • 1N4007 diode or m7 diode(smd) X 1
  • Terminal block X 2
  • Led voltmeter X 1
  • M3 bolts X 2
  • small piece of perfboard or veroboard.
  • potentiometer 5k ohm X 1
  • BD139 transistor X 2
  • Some wire
  • 3d Printer
  • Soldering Iron
  • Lots of patience !!!

Step 3: Build the Circuit

I have attached the schematic of the power supply . download and print it if possible to avoid any mistakes.

I have also attached the step by step building photos . So make sure you follow them so that it becomes easy for use.

soldering the transistor is tricky as we are backpacking each other .

Tip :- placing the transistors in some sort of vice will help to solder very easily.

The voltmeter that i purchased was having the wires soldered very badly.
So, I removed them and then soldered it with a clean solder joint.

Make sure that the transistor and LM317T ic are flush with PCB.

Step 4: Cleaning the PCB

After you have succesfully build your PCB as per the schematic then You may need to remove the PCB from the Veroboard.

For this I used DREMEL but you can use any rotary tool or you can the PCB to size before hand.

To avoid copper particles going inside the circuit I covered the entire circuit with Cello Tape. So that short Circuit is prevented.

After the cutting the PCB to use a blower or good blow from your mouth to blow off any copper bits .

Remove the cello tape and then inspect the circuit visually.

The Power supply will ready to be used now and will work flawlessly.

But I Designed and 3d printed the case to provide it more strength and rigidity.

So stick Around.

Step 5: 3D Designing and Printing

To provide a strength and good looks a 3D printed case is a must.

I designed my case in Fusion 360. and It is a two part Design

For 3D printing I used simplify3D to slice the model and then used my Anet A8 3D printer to print It.

You will need to M3 Bolts to join the two parts together.

Step 6: Finish and Demo

Here is the video Showing It in action.

So there You have it World's Smallest DIY Power Supply

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    Please be positive and constructive.




    And mine is ADJUSTABLE with a capacitor as a rotary knob.

    And what do have to say?

    WannaDuino STYLE.


    Great build !! Congrats


    Not the answer i was expecting! but oke.


    Not a PSU but a regulator, in PSU there is "power" !

    Exact master Rafununu.

    As always you are 100% right.


    You said it right . You may call it as a power supply in generally . But technically it is a regulator