where can a step up/step down transformer be used?

I want to know, I am just curious where a combined transformer would be used.

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iceng3 years ago
So, you know what a step-down transformer does.

Line AC to 12 VAC
It steps a higher AC voltage down to a lower AC voltage.

But if you turn the transformer around and feed it 12 VAC
it will provide Line AC as the output.

The same transformer is now a step-up.
It steps a lower AC voltage up to a higher AC voltage.

Here is how I apply this for an instant isolation transformer.
My TV Cable caused sparks to jump from the in house signal amplifier
connector to my hand and disrupting the TV screen every few minutes.

Buying two Radio Shack 12VAC transformers and wiring the 12V of one
to the 12V of the other makes an instant isolation transformer.

Hook one primary to the line and the other to the signal amplifier and
the incoming TV Cable potential is prevented from disrupting my
signal amplifier and the screen is stable all day !


nerd7473 (author)  iceng3 years ago
yeah i knew that about step up and step down transformers but I have only heard of an isolation transformer
iceng nerd74733 years ago
Happy to introduce you to something new,

Isolation transformers are 1:1 used primarily to make
industrial instrumentation across power phases between buildings
direct to line circuits or old appliances  safe to touch
while standing barefoot on a wet concrete slab ! :-)

You said "i knew that about step up and step down"
That suggests you ask questions that you know the answer to beforehand,
which is a lawyer's SOP.... 
nerd7473 (author)  iceng3 years ago
yeah maybe I should have researched instead of ask this question on instructbles
What parameters would this transformer have?

If it could take a 110VAC input and offer a 220VAC output on one end and a 12VAC output on the other end could have a number of applications. If the input offers enough voltage you can run a 220VAC air conditioner on the high side and with some added circuits you could run any 12VDC device or add a voltage regulator and drop the power to 5V and power any of your USB based devices.

It all depends on what your needs are and if it will fit your needs. Thats half the fun of electrical engineering. Taking a set of goals and finding the correct components and putting together the right circuit to meat those goals.
nerd7473 (author)  mpilchfamily3 years ago
is there a formula for calculating how much energy my output is by using the voltage and number of winds?
nerd7473 (author)  mpilchfamily3 years ago
ok those are good examples