Instructables

Make a simple 12 volt power supply

Picture of Make a simple 12 volt power supply
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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...
 
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Step 1: Things that you will need...

Picture of 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...

Picture of 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...

Picture of 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.

Some of you posters need to stay from electricity before you electrocute yourselves. Your questions prove that your are inept working with it. As for the person asking about the pinout, yes, the regulator pinout is WRONG. Hopefully anyone building this is smart enough to check the datasheet. {Pin 1 is the input, Pin 2 is ground, and Pin 3 is output).

aa salam2 months ago
Is it correct the pin out of ic 7812?
eli2412 months ago

hey :) what if i use a power supply with 3 amps? what do i do? do i keep the same capacitor values?

how to decide capacitor and resistor values at input and output sides?
TGRIMEAU9 months ago
I am planning to make wood portable laptops cooling fan and 12 volt power supply change to 2 volt ( red led ) and i did calculater of formula R=V/I R=( 12-2 ) / 0.015 R=( 10) / 0.015 R= 666.67 ohm resistor but no light red led with switch so try reduce to 325 ohm resisor but still weak light red led and agian try reduce to 265 ohm resistor to work bright light red led but 265 ohm resistor is still hot . Do you have any idea ??
xyndaen9 months ago
i think you will also need a cooler to protect 7812.

shalini negi10 months ago
its very nice, simple and has helped me a lot in completing my project.......
thanks a lot.....!!!!!
DeShark11 months ago
I know this was over 5 years ago, but you probably wanted to use a different transformer to reduce the voltage further. This would cause the power dissipation of the voltage regulator, keeping it cooler..
he bro you should use breadboard first to make pre-circuit....p
no problem one of my friend also burnt his transformer in lab :P and he has to submit power supply project and he buy new one dn't be disheart :P
i burnt my transformer when i made this supply...i dont know what went wrong..it was really disheartning
chetan_m.p2 years ago
what is the voltage of those capacitors..
The "voltage" of a capacitor usually refers the the maximum working voltage before the capacitor components degrade. The rectifier outputs about 16V, so use capacitors rated for at least 30V for safety
The rectifier will actually output a bit more. The rms value (average value) of the transformer is 16 volts, however during rectification the voltage output is actually the peak voltage of the AC input which would be the rms value x 1.41 or around 22 volts :)
fatfoohy4 years ago
could i run multiple 12 volt circuits off of this power supply at the same time? i'm looking to run 4 preamps and a stereo 15x15W amp off of it
Just put them in parallel. This circuit will not adequately power a 15W amplifier, however, so don't use it.
tjgamer19872 years ago
hey, nice circuit! i was wondering, im doin tha same type and i wanted 2 know wat did u hook your centertap connection wire and the primary wires from the transformer to?
The primary goes to a 120V outlet. The center tap is not connected.
tonygoffe2 years ago
Hello... Can someone do an IInstructable on how to "DE-SOLDER" rectycled componenets from a circuit board ?? ....PLs? PLS? pls?
We have a search box that allows you to find instructables like that. Trust me, there are many.
hello there i have a 12 v power supply it contain only one 1000uf capacitor and bridge problem is it shows output morethen 12 near to 16 etc Question is can i reduce it by adding a resistor if yes then how to calculate resistor for this circuit and where to place it
i hope to hear from you soon
You need a voltage regulator IC. Resistors are not for burning off voltage
mrmerino1 year ago
Holy cow, this comment section is just packed with the neediest electronics noobs anywhere on the internet!
Yep. I like the comment below about the inductor values or the ones where people ask for a version that supplies ONLY 200mA.
ache0031 year ago
what is the voltage rating of the 3300microfarad capacitor? please answer..
ahmedali1 year ago
how can i change current to my desire value??? plz plz tell me
for example if i want to change 1A to 500mA from above mentioned circuit
Relax. Current follows voltage. If you have 24 ohms across the output, it'll sent out .5 amps.
how to built the body of the power supply.

thanks.
ahmedali1 year ago
how can i change value of current to my desire value like 500mA from 1A???
ahmedali1 year ago
plz reply as soon as possible
u did'n mention cap voltage
this is a solution of my problem..... thank you up-loader....
Zinozee1 year ago
Lovely, we have a very similar project in skool rite now, hope to use this effectively. thanx
Zinozee1 year ago
Lovely, we have a very similar project in skool rite now, hope to use this effectively. thanx
Awesome Circuit!

I'm only just starting out in electronics and still trying to wrap my head around reading schematics but with you physically showing the finished product & components pictures/list makes it even easier for someone with very little experience to construct!

A Major Thank You !!

Um, i wonder if you'd be able to help out on a very similar circuit for me please ?

Im trying to get my four batteries (3.6v each in series) to power my wireless pinhole camera's receiver but dont know how to get the power down from 14.4v to 12v (No more than 500mA), DC to DC...

Please would you be able to help in this regard ?

Many thanks in advance if you can help this troubled-soul !
fkhan142 years ago
Can i Use Bridge in Replace of diode in 12V power supply........????????? please answer me as soon as possible
fkhan142 years ago
Can i Use Bridge in Replace of diode........????????? please answer me as soon as possible
fkhan142 years ago
Can i Use Bridge in Replace of diode........????????? please answer me as soon as possible
ninjatails2 years ago
Why are the capacitors connected to ground? Are they just there to waste electricity or what?
They stabilize the current and prevent spikes in the output
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