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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...
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
<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>
I want 2amps
Can i use a 1000uf capacitor
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>He told in the instructable. Please carefully read the circuit diagram :)</p>
<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>
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>use boost converter. </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>
<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>
<p>Just use 7805 voltage regulator. It gives 5v output and max of 1.5Amps.</p>
<p>I need to convert 115volt AC 12volt 4AMP <br>for a refrigerator water dispenser</p>
<p>how to identfy the primary and secondary winding</p>
<p>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).</p>
<p>I agree.<br>A universal rule for the NatSemi 78xx is that with the model number &amp; batch # / datecode facing toward you, every so often IGO and play with linear regulators.</p>

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