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Step up transformer? Answered

 i need to step 90vac (ballasted) to 300v any help 

or if 9-18vac 2a is easier 


Then you need a 1:3.3 transformer with a sufficient current rating for your job.

have I missed something here??

Well the current dosent really matter the 90 pulls barely any current

how got no is is i had a 120 in 12v out and i put 120 in and the with the 12 out i hooked it to the secondary of a 12v coil just like the first one so

It seeps down to 12 then steps up to 90

The current you draw from the transformer WILL matter quite a lot - It is the key to the gauge of the wire and the number of turns you need.

transformer calculations can be found if you search round the web or look at ICENG's advice.

Winding your own is a long and tedious process that may or may not work in the end for all sorts of reasons.

We don't know what your trying to do in the end so it is hard to advise.

My feeling is that at the moment your electrical knowledge isn't good enough to be able to DIY a transformer that does what you want.

Dealing with mains electricity is dangerous as I am sure you know and connecting transformers back to back can lead to problems if your not sure what is happening.

For the moment I would shelve this project until your expertise gets better.


6 years ago

I'm no puppet toy maker, but on changing energy from 90 V to 300 V
are you asking DC or AC ?

What does 9- 18v 2a mean ?


Its 90vac and i need 300vac

the 9-18v 2a wass if it wass easier to step that up rather than 90vac ballasted

OK that is straight forward...  90 vac to 300 vac is a transformer away.

Any industrial standard 440 vac step down to 120 vac transformer is
very close to your need [1: 3.67] it will step up 90 vac to 330 vac.
Allied, Mouser maybe eBay has stock.

Then TRriad makes and stocks lots of transformers
or do you want to wind your own ?


I could wind my own

so its 1:3 how many wraps on the single

You have great ibles, so I know your skill set
You could wind a transformer.
  • You will need a E I iron core,
  • Two gauges of magnet wire,
  • An appropriate bobbin
  • Fish paper insulation,
  • A winding setup (I use a 16V drill and 1/4-20 screw + nut)
  • Several hundred turns for primary
  • And hundreds on the secondary coils,
  • Shellac or epoxy impregnation.
  1. Once you have an iron core you can start to design
  2. You have a turns ratio and try for a current output
  3. See if the windings will fit with a 60% beginner fill factor
  4. Purchase the reels of magnet wire for three winding tries
  5. Wind, Stack and Test
  6. Encapsulate
And you have a DIY Xfmr  : )


i don't have any ibles? im advanced at my electronics im 15 just turned and do lots and lots i don't post tho cuzz i don't have the patients to take pics off everything but don't take me wrong i do alot and and 1 to 3 so one hundred primary and 300 secondary

Sorry confused you with someone.

Not that easy.   Read my steps, lots of math and design and work.

First you need an iron core then figure wire then figure turns
I just know most line and higher Xfmrs are at least 200 turns.

You should buy a 440:120 transformer.


Would maby a hand wrapped flyback work so theirs fewer wraps

The primary yes but the secondary must withstand 20kv a very difficult insulation
situation i would not try winding myself.


Without a very well equipped workshop and high vacuum pumping gear, you can't make a magnetron.

+1 although the first Magnatrons were hand made this isn't something you can do easily.

The rest of your question makes little sense more information required like where do these figures come from.

I need to step 90vac to 300vac thats all i need the 90vac is ballasted so would 9-18vac be easier to step up