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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...

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!
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?
<p>there is resistor in the picture. but there is no resistor in the schematic. Where did I should put the resistor?</p>
<p>it is for the LED an add on to the power supply</p>
<p>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</p>
Ok thanx for this but you didn't mentioned Capacitor Voltages. Plz let me know which voltage of capacitor i use
<p>how to calculate value of capacitors, diodes and restistors to be used?</p>
<p>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</p><p>now put all in one single equation you get, </p><p>Ixt=CxV</p><p>your supply voltage is= 12v</p><p>t= 3x10^-3 sec</p><p>i= what you want </p><p>V= 12v</p><p>and you get Cap value.</p>
<p>Please try to explain my circuit if anyone can ??</p>
<p>it's a inverter with PWM ci.</p>
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.
<p>you should not run modem from USB output of laptop </p>
<p>use boost converter. </p>
<p>I've bought a 3A 12x2v tramsformer. . from half m getting about 18v output. applying bridge rectifier i filtererd into DC. But my problem is using LM7812 or LM7809 it gets extremly hot although i've used heatsink... so my question is </p><p>1. What can I do to avoid overheating ?</p><p>2. How can I use this 3A transformer as 1 or 1.5 A if i need? </p>
<p>Using 9 volt battery how can i get 1.5 amp or 2 amp from the circuit?</p>
How do i control current optput. Say I need a supply with 5.1 V and 2. 5 Amps. What additional things are to be added
How can i get 4amps
<p>how make 12 volt power supply and its connection?</p>
Simpal formula<br> You will take 12v tramsformer and 4 dioads and 24v 1000uf capacitor
I want 2amps
Can i use a 1000uf capacitor
<p>can i use 3amp transformer</p>
<p>awesome project</p>
<p>awesome project</p>
<p>awesome project</p>
<p>awesome project</p>
<p>pzlz post a circut diageam </p>
<p>is ke diyagram b pist kro na </p>
<p>how if it has to have an output of 24volts?</p>
<p>Desn't the LM7812 Have a 1.5AMP output?</p>
<p>I ask why compute the value of the capacitor</p>
You didn't tell about the volts of capacitor...<br>I've got 4700uF 25v<br>100uF 25v<br>1uF 63v<br>100uF 16v<br>capacitors and 15v 750mA transformer ...<br>Can I use them ?<br>If no, tell me all the components with proper specifications of them.<br>Thank you
<p>what kind of modifications are required if i want to get current up to 3A instead 1A?? <br></p>
<p>Can u tell me what is the resistance of resistor that u used that LED.....????plz reply as soon as possible ..... i have to made it urgent for my final project...thnkx</p>
<p>i dont think you need the LED</p>
Can i use 103nF replace of 100nF ???
<p>Yes</p>
<p>paul why they used 4700 micro farad capacitor ? any calculation for this?</p>
<p>@syed http://goo.gl/RSmg1Z Refer this link hopefully you get it </p>
<p>hey :) what if i use a power supply with 3 amps? what do i do? do i keep the same capacitor values?</p>
<p>1uF per mA is a good rule of thumb.</p>
<p>I am sorry if I sound new at this, but I am. I just blew a capacitor and burned my finger (lol). Instead of using a transformer I used a 12vdc adapter. I am looking to pull about 1A and your comment says 1uF/mA. What capacitors are you talking about in this comment? Could you give me some direction as to how to wire from a 12VDC adapter?</p>
<p>if you need 12 v output use 7812 ic last two digit represents the voltage so if you need 5 volt ask for 7805,simple. </p><p>1. It will contain 3 pins</p><p>2. Pin 1 is input can give upto 24 v dc </p><p>3. Pin 2 is common(Neative)</p><p>4. Pin 3 is output ( Positive,(load))</p><p>5. But you can withdraw only 1 Amp max only with heatsink</p><p>6. Heat sink is not neccessary if only drawn only 50% of the rated current</p>
<p>So you will want a 1000uF electrolytic on both the input and the output pins, with the - stripe to ground, with a 25V (or 16V) working voltage (WV). I'd be willing to bet you either put the cap in backwards or used one with a WV that was too small.<br><br>Use the circuit diagram in the article but chop off the diodes and transformer. If you are dropping 12V to 5V at 1A (I assume this is what you are doing) you'll need a heatsink. 7805s do not smell nice when they are burning ;)<br><br>If you are trying to keep 12V as 12V a Zener diode might be a better option, but that's a different implementation entirely.</p>
<p>will I get 12v 10a from this circuit if I use 12v 10a stepdown teansformer</p>
<p>connect more transistor in parallel get more current.......high power transistor...and also used heat sink for all ic and transistor....</p>
<p>What should I change to use batteries (24volts) instead of the transformer and get 1A out and what is the efficiency of the circuit?</p>
<p>if planning to use any power supply for motors you should add a protection diode between output and input on the regulator</p><p>http://www.learnabout-electronics.org/PSU/images/78xx-protection-diode.jpg</p>
<p>Can you give me a schematic and materials for 12V input voltage with an output 5V and 2A ..thank you in advance..</p>
<p>BUT you should reduce the transformer output to 7.5 volts.</p><p>otherwise you create too much heat reducing the input voltage</p>

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