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Hey guys

So you're just starting electronics or have been a hobbiest for a while now.

A power supply is a must for, so in this instructable I am going to show you how we can make a very basic and easy to use power supply for practically nothing.

The power supply can deliver upto 20 volts at 3 amps and is more than enough for most tasks and with the way we are dependent on our smartphones (or USB devices in general) I decided to add an USB power supply that can be used to charge your phone (completely optional though I just used it for my convenience)

In a previous instructable I had shown you how you could build a power supply which had a couple of fixed voltages and a variable one. Though the build was a little more complex I hadn’t included a high power output option thus making it useless for a variety of applications. After sizing up all options I have figured a good, viable and most importantly easy to build (ie beginner friendly) power supply.


So without further ado, let’s get right into

Step 1: Materials and Tools

You would require the following parts to build the power


1. Old laptop charger (the heart of the build…you can use any other power supply also but laptop chargers are generally compact and can deliver enough power also.)

2. Voltage regulator – I have used a lm2596((buy here) as if deliver up to 3 amps ) based voltage regulator module but you can use an lm317((buy here)which can be made easily and I will explain it in a further step) but I don’t recommend using a voltage divider(it being very inefficient)

3. A enclosure to make the build look good – I used an old watch box but one can use anything from cardboard to custom CNC box.

4. A switch - make sure it can handle the power coming out of the power supply

5. A panel mount voltmeter (buy here)though this is extra and not required it adds a lot of convenience

6. Alligator clips – completely optional

7. Banana clips to make a swapable connection point- I didn’t use them though

8. A 5v AC to DC step down with a USB port to charge up your electronics OR a 7805 DC-DC step down converter to power the voltmeter.

9. Potentiometer with a knob would be good

10. Wires

The tools you will require apart from the basics like a screwdriver are

1. Soldering iron (with solder)

2. Dremel or any other rotary tool –optional

3. Multimeter-optional

4. Drill-optional

5.Hot glue gun

6. Tape

an hour or two depending on your experience and how elaborate you make the build


Most probably your laptop charger would be covered in thick plastic which is useless as we would be enclosing the whole thing in an enclosure.

This step can be very dangerous as we would be dealing with exposed connections and should be performed only when the power is off ie the charger is not connected.

Though this isn't necessary but you can start out with a dremel or a hot knife and slice the plastic where they appear to meet.

Next you would see a few more layers of plastic and a layer of metal which is earthed which can be left as it is.

Now is a good time to connect the AC input of the 5v wall vort to the AC input of the adapter or if you are using a 7805 you can hook it up to the DC output of the laptop charger now(according to diagram given in the pics.)


So the voltmeter has 3 wires

RED- the power wire which gets connected to the positive terminal of the 5v supply

BLACK- ground and gets connected to the negetive of the 5v or the common ground

WHITE- the sense wire which gets connected to the output of the supply...LATER

after giving the voltmeter power the display should light up.


If you have chosen to make a regulator with a LM317 then i have included a schematic diagram or if you have bought one then make the following connections

The input has to be connected to the output of the laptop charger

If you have bought a voltage regulator then there would be a potentiometer on the board itself which can be replaced by potentiometer (shown in the materials step) with wires for extending it.


Place all the parts in the enclosure in a compact way and drill in holes for the switch and the pot and make a hole for the voltmeter.

if you want to add a switch add it between the negative output of the laptop charger and the voltmeter as shown in the diagram.This way the voltage regulator part switches off but the USB functionality still remains on.

Give the whole thing a coat of paint and voila its done.

Any queries in the comments thanks for reading do follow me for more such builds.

Power Supply Contest

Third Prize in the
Power Supply Contest

Explore Science Contest 2017

Participated in the
Explore Science Contest 2017

Invention Challenge 2017

Participated in the
Invention Challenge 2017