Make a Simple 12 Volt Power Supply




Introduction: Make a Simple 12 Volt Power Supply


Have you ever needed a 12 volt power supply that can supply maximum 1 amp? But trying to buy one from the store is a little too expensive?

Well, you can make a 12 volt power supply very cheaply and easily!

I needed a 12 volt power supply for my project, the SSTC (Solid State Tesla Coil), and also made this instructable because it might be use full to someone...

Step 1: Things That You Will Need...

Things that you will need to make this power supply is...

  • Piece of veroboard
  • Four 1N4001 diodes
  • LM7812 regulator
  • Transformer that has an output of 14v - 35v AC with an output current between 100mA to 1A, depending how much power you will need. (I found a 16v 200mA transformer in a broken alarm clock.)
  • 1000uF - 4700uF capacitor
  • 1uF capacitor
  • Two 100nF capacitors
  • Jumper wires (I used some plain wire as jumper wires)
  • Heatsink (optional)

You should be able you get most (maybe all) of the parts at Radio Shack or Maplin.

Step 2: And the Tools...

Also you will need the tools to make this power supply...

  • Soldering iron
  • Wire cutters
  • Wire strippers
  • A thing you can cut veroboard tracks.
  • Hot glue (To hold components down and make the power supply physically strong and sturdy.)
  • And some other tools that you might find helpful.

Okay, I think that is about it, lets get to work!

Step 3: Schematic and Others...

If you want a 5 volt power supply, just simply replace the LM7812 to a LM7805 regulator.
Datasheet for LM78XX

If you are going to pull out about 1 amp from this power supply, you will need a heatsink for the regulator, otherwise it will generate very high temperatures and possibly burn out...
However, if you are just going to pull out a few hundred milliamps (lower than 500mA) from it, you won't need a heatsink for the regulator, but it may get a little bit warm.

Also, heres the schematic...
I also add in an LED to make sure the power supply is working. You can add in an LED if you want.

Step 4: Make It!

Well, read the schematic and build the power supply!
If you don't know how to read schematics, you might want to look here.

Make sure you get good solder joints and no solder bridges, otherwise your power supply won't work!

Oh, If you don't know how to solder, read this great instructable! How to solder!

Step 5: Test It!

After you had built your power supply, test it with your multimeter to make sure they are no solder bridges.

After you tested it, put it in a plastic box or something to protect you from shocks.
But do not operate the power supply like I did, it is very dangerous because of the mains voltage on the transformer, you or somebody will get badly shocked!

My power supply has 11.73v output, not too bad, I don't need it to be exactly 12v...

Step 6: Done...

You had built a cheap power supply! You can use it for what ever your needs...
But again do not operate it without any protection!

If you need any help, or questions, or any thing, make a comment!



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    239 Discussions

    This is a really big help. Could I please get the complete diagram of the schematic? I wish to use this circuit for learning purpose.

    i need a CHARGER for my 3sm 12Vbattery. i have here a turoidal transformer. the label says MS2500 IN:AC240/60Hz, OUT: 19V-0V-19V and 15V-0V-15. CAN YOU SHOW ME A SCHEMATIC.

    sry why IN4001 used here in place of IN4007

    If i use a transformer of 2A, how much current will be generated after making supply to 12volts? it will be same?

    please respond asap.

    1 reply

    what about 12 v 640 a ??

    Ok thanx for this but you didn't mentioned Capacitor Voltages. Plz let me know which voltage of capacitor i use

    1 reply

    Since this is a 12v circuit, you may use 24v capacitor. Capacitor voltages are usually calculated as twice as the circuit voltage.

    Hello everyone
    One of the most used electronic circuitry is its many applications
    The simplicity of the electronic circuit is a good job
    12 volt circuit

    Sounds like a good project. However, I am wondering how steady the output of the power supply is. I am in need of a small power supply of this voltage for an audio project, and given the application I need a fairly steady DC waveform with minimal ripples. Would this supply work for that?

    there is resistor in the picture. but there is no resistor in the schematic. Where did I should put the resistor?

    1 reply

    it is for the LED an add on to the power supply

    I need a 12 V and 4,167 amps power supply can anyone draw me a scheme and tell me the needed scheme parts ? Also it would be very good to know how to make calculations for needed parameters

    in a bridge converter each diode conduct only 3milisecond or 3x10^-3 sec. capacitor Q=CV. now we Know i=dq/dt or Ixt=Q

    now put all in one single equation you get,


    your supply voltage is= 12v

    t= 3x10^-3 sec

    i= what you want

    V= 12v

    and you get Cap value.

    Please try to explain my circuit if anyone can ??

    ckt diagram.jpg

    Please tell me how to make 12volts DC supply from USB port output of my laptop that gives 5volts output..... I want to give power to my modem(that requires 12v dc) from USB port of my laptop.

    1 reply

    you should not run modem from USB output of laptop