How to Build a Simple 12 volts power supply circuit with a hammer

Today, my son builds a simple 12 volt power supply circuit for a 12V solar pump. It is an Unregulated 2A Power supply. Because a load is DC motor only.

Why you should learn this?
It is an example of an unregulated power supply working principle. Which they are basic of every power supply.

How to Build Simple 12 volts power supply circuit

How it works

I teach son to understand the working principle of this projects.

The main principle, we use this project to reduce the voltage from AC-line 220V to 12V DC.(12 volts filtered power supply)

In Figure 1 The AC 220V 50HZ is connected to the circuit through S1- ON-OFF switch and F1-fuse to protect this circuit.

Then they flow through a 2A transformer to reduce voltage into 12V AC.

Next, through both Diodes to rectifier AC to DC converter.

Then, at a capacitor as the filter to DC voltage.

The LED1 is power on display and R1 limit current for LED use.

schematic-diagram of Simple 12V 2A DC power supply

Figure 1 the simple 12V 2A Power supply circuit diagram

Parts you will needs

T1: 12V CT 12V, 2A transformer
D1,D2: 1N5402, 3A Diode
C1: 2,200uF 25V Electrolytic capacitor
R1: 1.2K 0.5W Resistors
LED1: LEDs as you like
S1: ON-OFF switches
F1: Fuse 1A
Copper wires and nail 0.5inch, AC line power

Make 12V DC power supply

This project, my son builds 12 volt filtered power supply with himself many steps.


First of all, put the paper on a sheet of plywood and Hammer a nail into the parts joint. (Figure 2)

He soldered all parts on the nail head instead of the PCB. (Figure 3).

All parts of the AC line is high voltage I connect them instead of my son.

Hammer a nail into the parts joint

Figure 2 Hammer a nail into the parts joint

soldered all parts on nail head

Figure 3 soldered all parts on the nail

measure voltage at output is 17V No load

When completed, He measures the voltage at the output is 17V No load (Figure 4)

Figure 4

Then, he tries to apply the DC pump as load. As the video below.

measure current of load

Then He measures the current of the load is about 0.9A as Figure 5

put it into the box

This project is applied at outdoor so he put it into the Plastic boxes to protect water as Figure 6

12v 3 amp power supply circuit diagram

If you want 3A output. It is easy to change a few parts list:
1. Change transformer to 3A current.
2. Add more capacitor filter to 4700uF. By adding another one 2,200uF in parallel.

Is it easy?

This project of homeschooling boy is fist Electronic times we have happy it works great.

Learn more: Designing 12V 5A Linear Supply

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2 thoughts on “How to Build a Simple 12 volts power supply circuit with a hammer”

  1. I remember doing this as a kid. My dad had some wood and some brass tacks. I was curious to what commonly available metals I could get solder to “stick” to. I found out brass tacks took solder easily, so I built a siren with a schematic I found using those brass tacks and wood.

    • Hello James,
      Thanks for your feedback.
      Your experience makes me smile and feel very warm.
      The Electronics is not obsolete. It is a fun activity for the family.
      Unfortunately, now. My son does not like electronics.
      But I will prepare the content and learn for him.
      I have believed that he will come back to love electronics again.

      Have a good day.


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