Re: DIY HV transformer

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Christoph,

On 12 Jul 2005, at 12:00, Tesla list wrote:

> Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>
>
> Hello everyone.
>
> As you may have noticed during the last few days, I had some trouble
> with my 6-mot-stack, which finally lead to a failure mode that makes
> diagnosis very difficult, so I wanted to try something else: Wind my
> own transformer: first pictures of the winding process can be seen
> here: http://www.luebke-lands.de/tesla19.html along with some basic
> specs.
>
> The transformer is intended to be run unter oil, but another problem
> arises:
>
> The core material I am winding this transformer on, is the core of my
> former ballast coil, which means I no longer have one. Now, can I
> incooperate some shunts or airgap to limit the current so that I don't
> have to build another ballast coil? The core is basicaly rectangular,
> with each of the coils on one leg left and right... Maybe someone has
> an idea here. Maybe even with shunts, that can be moved by means of
> some mechanism while the transformer is still under oil....
>
> I'm thankfull for any suggestions.

If the primary and secondary are on separate leads you may need no
ballast at all. The proximity of the windings to one another dictates
the degree of leakage inductance present. I have used such
transformers in the past no problem at all. The unknown is the amount
of leakage inductance and the Cp size with which the transformer will
resonate at Fmains. I'd try it ungapped with a Jacob's Ladder first.
The worse you can do is pop a circuit breaker.

Malcolm