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Can I make a step up transformer out of a step down one, and f I can how? Answered



Best Answer 8 years ago

It will work to just reverse the transformer as others have suggested and I also have done before. HOWEVER, i dont recommend putting 110 volts into a 12voltAC reversed transformer and expecting to get a couple thousand volts or a thousand volts out! It will just likely fry the transformer or you will get hurt. If you place 12 volts AC into it ... you will get 110AC out. It will likely not be as efficient. be carefull out there.

.  Thanks. My warning about specs didn't make it very clear that voltage is a very important spec. You have to stay within the rated voltage or you run the risk of punching through the insulation. Ya ain't gonna get kV out of a wall wart.

Yes you can but it depends on how high the voltage is you want from it.
A step down transformer is built to deal with low voltage output, say 700 volts or less, give or take a couple hundred volts.

Its housing or lack of it leaves a step down transformer full of high voltage leaks due to sparking. If high enough, these high voltage sparks short the circuit within the transformer leaving you with hardly any output at all if you're lucky.
Step up transformers are built with high voltage output in mind so are carefully constructed, well sealed and insulated against internal high voltage sparking (why they are generally more expensive).

If this is the type of high voltage you are after but still insist on using a step-down transformer all you'll need is time and patience.
Dismantle your step-down transformer carefully and rewind the new secondary coil (originally the input coil when used in voltage step down configuration) only this time taking care to space out coil turns more and well insulate the ends exiting the transformer. Admittedly this process can be quite tedious but if faced with no other choice is one way to go about it.

* High voltage shocks are painful and in a few cases can kill so tread with great care.

Don't listen to the other dudes. If you reverse a mains-transformer with mains it will break. What do you want to do, how much step-up do you need and from what?


.  hmmmm  I've reversed at least three xformers over the years without problems.

I did one. And didn't do it again.


Lemonie's right. WITHIN LIMITS a transformer is "reversible" - on paper. The PRACTICAL side of things is such that saturation effects in the iron of the core WILL make it go

. Turn it around. Ie, make the input the output and vice versa. Double-check power and current ratings and make sure you stay within specs.