# Re: Power Transformer Basics

```Greg,
I have built my own transformer for tesla coil use.  I have
information and equations on my web page about it.
http://members.aol-dot-com/tesla00/o_index.htm  For a multiple
layer iron I used A(in^2) = 74 / frequencey(Hz) * (volts per turn).
So far my transformer has worked great.  Its rated at 29kv 300
ma, but I think I can push it to 400ma or more.  I will find out :).
Its iron lamination size is 1/64 or 64?  I know that there is 64
layers of iron per inch?

The KVA per cross-sectional square inch of core doesn't
really matter.  Its just how much heat the transformer can
dissipate.  About the regulation.  I didn't worry about it.
Since we are building our transformers for most possible
power, smallest, and cheapest the efficiency of the
transformer doesn't really matter.  I built my transformer
with a total turn insulation of 360 mils of polyethylene.
Insulation to the core is 240 mils of polyethylene.  With
center tap grounded to the core.  I built it this way to
protect against spikes/interference from my tesla coil.

Just trying to help. :¬)
Erik Schulz

>> When designing a homebrew HV power transformer for
>> use as a Tesla coil power supply, what is a suitable
>> value of VA per cross-sectional square inch of core?
>> Also, how many turns per volt per square inch of core?
>> I'm assuming 60Hz operation, and "transformer iron"
>> core material.  I'm also ignoring regulation.  How does
>> "tight" -vs- poor regulation affect the above ratios?
>> Does a tightly regulated transformer require more turns
>> per volt, or less?

```