Re: Newbie question

To: tesla-at-pupman-dot-com
Subject: Re: Newbie question
From: Tesla List <mod1-at-pupman-dot-com>
Date: Wed, 15 Oct 1997 13:59:30 -0600 (MDT)
Approved: mod1-at-poodle.pupman-dot-com

---------- Forwarded message ----------
Date: Wed, 15 Oct 1997 15:06:50 -0400
From: Alan Sharp <100624.504-at-compuserve-dot-com>
To: "INTERNET:tesla-at-pupman-dot-com" <tesla-at-pupman-dot-com>
Subject: Re: Newbie question

Aric
>
> 2.  Has anyone built a HV switching supply for a Tesla?  I'd like to
build
> a 15 kVDC supply using an off the shelf switching controller IC from
> National Semiconductor.  The tricky part will be the boost-transformer. 
I
> thought I'd use a U or toroid core of 77 type ferrite wound with a 1:125
> ratio.
<

Yes I have one working that gives a 12" spark.

The most common solid state designs follow Duane Byland.

A switching controler chip, power devices in a half bridge,
push pull, or full bridge configuration, driving a step
up transformer, driving an air wound magnifier coil.

The IRF740 is a useful mosfet on price/bang.
IGBT's generaly don't switch fast enough.

A step up transformer with a ratio of 1:125 will
probably breakdown - 15:1 or 20:1 transformers,
fed from 200V are difficult enough. But then I'm
using fairly compact E cores.

My advice would be to try the magnifier set up
and to start at modest power levels and build up
slowly.

If you do use a resistor to monitor primary
current levels make sure it is a low induction
type - not a wire wound.

Have fun,

Alan Sharp (UK)