Re: Very HV transformers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Peter Terren" <pterren1-at-iinet-dot-net.au> 

I was given my dental x-ray transformer free (actually, he in turn paid
AUD$1 for it on eBay). It is a 60 kV 50Hz 240VAC unit measuring only about 5
inches long. It has no shunts and can take a huge amount of power under oil.
A lot more powerful than an NST.


I have used a voltage doubler with a diode (290 x IN4007) plus 4 Mica caps
to give 0.015uF at 80kV. This gives about 100kv when run at about 200V in.
The sparks are 5 inches plus and are fairly quiet and hazy as I limit peak
current with a 100k resistor and an inductor. It causes resistor arcover at
about 80kV on my homemade HV meter.

Sadly I think I have overvolted the transformer  :( (but not before I got
the pics) ;D



I have not seen a mains transformer that can deliver a spark greater than
its length albeit through a doubler.



I also have a 100kV mobile x-ray transformer from an x ray repair place that
was doing a cleanout and cost perhaps AUD$100. So far I've not taken it
apart to rewire it to bypass the klystron switching.



I'm not aware of anyone using them for TC work and they would pose
particular problems with the spark gap and quenching and the cap would need
a much higher voltage rating.



Details on my site in the HV section.



Cheers

Peter (Tesla Downunder)
http://tesladownunder.iinet-dot-net.au




 > Original poster: pepperman-at-softhome-dot-net
 >
 > I've seen several people mention getting various HV transformers
 > that come from unusual sources (e.g. from X-ray machines).  How
 > do you manage to get ahold of these (I'm especially wondering who
 > you ask), and how much do you usually pay for them--or do you
 > somehow scavenge them?  Also, how do you use transformers
 > with such incredibly high voltage for Tesla work, if you do?  (I
 > remember a mention of a 90 kV transformer at one point!)
 >
 > Michael Johnson