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Re: Replacements for the neon


From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Tuesday, December 23, 1997 10:15 PM
To: 	Tesla List
Subject: 	Re: Replacements for the neon

Hi Bert, all,
              I have routinely wound flyback transformers and chokes
to produce around 20kV peak.  I do use PTFE as inter-layer insulation.
The trick is to coat each layer of wire after it is wound with a good 
quality air-drying electrical varnish before apply the next PTFE 
layer. The windings are *guaranteed* to slip if this is not done.
Crossed turns are a recipe for failure. A simple winding machine and 
hand guiding of the wire at the very least is mandatory. Also, each 
layer should several fewer turns than the previous one so that the 
top layer is shielded from the layers below it to some degree. There 
should also be sufficient creepage out the sides of the layers to
avoid flash-arounds.

FWIW,
Malcolm
 
> From:   Bert Pool[SMTP:bertpool-at-flash-dot-net]
> Sent:   Monday, December 22, 1997 8:42 PM
> To:     Tesla List
> Subject:    Re: Replacements for the neon
> 
> 
> >
> >From: Paul Anderson[SMTP:madhobbyist-at-geeky1.ebtech-dot-net]
> >Sent: Sunday, December 21, 1997 11:03 PM
> >To: tesla-at-pupman-dot-com
> >Subject: Replacements for the neon
> >
> >Finding a used neon sign transformer in my area is proving most
> difficult,
> >so I was thinking about winding my own transformer to replace the neon.
> >Any thoughts?  I was thinking a 200:1 turns ratio would be good...
> TTYL!
> >
> >
> >
> >---
> >Paul Anderson
> >Hacker, Mad Scientist, Machinist, Publisher, and Author
> [snip]
> 
> Paul, I wound a 2 kva transformer on a core from a big isolation
> transformer that I bought scrap.  I used 28 gauge wire for the
> secondary, and attempted to use teflon insulation between layers.  Do
> not do this!  Too soft, and too slippery.  The insulating sheets
> between each layer of wire need to be a stiff paper that will allow you
> to wind each layer perfectly flat.  Any winding defects such as
> crossovers, bumps, spaces, etc., will peopogate on through each
> following layer, just getting worse and worse.  It took hours and hours
> of hard hand labor.  I put it in oil.  I ran it.  It lasted fifteen
> seconds before it failed.  I will never attempt this again.  I know at
> least one other soul on the list *did * successfully wind a hv
> transformer and made it work.  Perhaps you will receive some positive
> info on construction - all the info I can supply is how *not* to build
> one <grin>.
> 
> Bert Pool
> TCBFW
> bertpool-at-flash-dot-net
> 
> 
> 
>