A Simple Power Supply.

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Introduction: A Simple Power Supply.


OK, I had this plug-in charger going spare. I'd bought it to replace a lost power-supply for a car DVD player, but it wasn't up to the job.

Time to give it a new lease of life.

Step 1: Oh, It's *so* Hard to Make...

I lopped off the useless jacks, split the wire, stripped the end and soldered on the crocodile clips.

It was nearly as quick as it took to type this step.

Step 2: The Interesting Bit.

OK, so I have a cheap power supply (the charger cost me £2.99), so what?

Ah, because I can choose the voltage! It's a bit hard to see in the photo, but there's a sliding selector for anything from 0V (why??) to 12V, and a little recessed switch to swap the polarity as well.

One "problem", the voltage on the scale is wrong - a voltmeter across the crocs reads about 50% higher than the number on the scale. The working voltage is actually 4.5V - 17V.

It's not just a toy, it's been used in anger, to test the bread-board circuit for the version of Minty Beating Valentines Heart I'm part way through (https://www.instructables.com/id/EG7BX7AVJ7EXCFLX7K/ - I'm just looking for a suitable box to land a dragonfly on).

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You are wrong about the volts out.The voltage will drop when you load some charge in.These supplies normally are not stabilised.

Good idea. You also might want to make one leg of the "wire split" a bit shorter than the other to help keep the two clips from accidentally coming together when not clipped onto whatever you are powering up.

Good thought (although the little green sparks are fun...)

Yeah,but a breaker trip is also annoying when you make sparks:-)

Question, I have a fan from a computer, can I use a the above adaptor to convert into an AC fan? What would the necessary output requirements be on each? Thanks in advance.

Yes, you can (I do). I did nothing to the fan except rip it out of a dead PC.

Just check that you aren't massively over-powering the fan (although I think most PC fans are 12V).

Excuse my ignorance, but how would I know if I am "over powering it"? What should the ideal output be on the plug converter be? Thanks in advance, I need to use something like this for a fan in a bathroom.

Read the fan, see what it says it needs, and read the power supply (wall wart) to see what it puts out. You may be wasting your time, though - a single PC fan will not be able to ventilate a bathroom well enough to prevent condensation or mildew.

Actually one of my wall wart transformers says it puts out 12volts DC but it really puts out closer to 18?? (without a load on it)

As others have pointed out, a lot of these are not regulated properly, and they only give the correct voltage through a load.