winding your own transformer

From:  Tabbal [SMTP:bigboss-at-inquo-dot-net]
Sent:  Monday, January 26, 1998 4:00 AM
To:  Tesla List
Subject:  Re: winding your own transformer

> I've had quite a bit of experience with transformers.  I've worked with
> tesla coils for about 18 yrs. now and have been a High Voltage, High

A question for the Transformer experts out there... Why do we center-tap
them? I just haven't been able to figgure out what this does. 

Also, I have a project I'm looking at that calls for the following custom

4 turns, center-tapper primary, 16 turns, center-tapped secondary; 5-mil
copper foil wound on a Ferroxcube ETD-34 core.

So, the center-tap question applies here, but do they want the actual
windings to be copper foil? Seems like an odd matterial to use for a
Transformer. I assume it must be insulated by me with paper or something.
Would Polyethelene work? It's for lower voltages, should peak at about

If it is to be wound with foil, the tap could just be a wire soldered on
at the middle of the winding, right?