How to modify cell phone charger to power supply.

[atxuser]

Well, first thing I ll tell is I am not English, so please tolerate my English. Ok, the problem: I have a lot of cell phone chargers(for example Nokia) and dont know what with it. But I got very useful idea --- make from it DC supply. I mean make from 3,7 V phone charger 12V transformer. I heard it is possible, and I saw it is truth, but I forgot to ask how to make it(or more precisely how to modify phone charger) ;-) . I saw on that phone charger capacitor and some diods. Anybody knows how to make it? Please, tell me how, I will be thankful. Sorry for my bad English.

 

[seadolphine2000]

These phone chargers have "Step Down" transformers those step the 220V AC down to around 6V AC. Then, using rectifying diodes and potential dividers, you get the 3.7V DC
To reverse the process, you will need to step the ~6V AC up to 12V AC and then rectify this 12V AC to get the DC voltage you want.

It's much easier to make a power supply from scratch than to modify the cell phones chargers.

Hope this helps.

 

[zuisti]

A phone charger with a relatively high weight IS a simple power supply. It has a small tramsformer with a 230 or 120 v primer and a low voltage secunder coil usually between 4 and 8 v. It has a Graetz bridge (or 2-4 diodes) to rectifying, and a relatively big polarized electrolitic capacitor (100-1000 uF) for filtering.
So it can be used as-is for supplying other (DIY) electronic circuits, w/o any modifying, but may have an additional stabilizing circuit ...
It's impossible to make a 12v supply from a 3.7v Nokia charger (would have to be rewound the transformer...)

Remember the "lightweight" chargers are all switch mode power supplies, it is not an easy task to modify them (even if they can be taken apart : - ).