Re: Vacuum tubes (and Cheesehead Teslathon)

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Hi John,

I agree with you - the Cheesehead Teslathon was really GREAT! Thanks, to 
D.C. Cox for hosting the first of what, hopefully, will become a 
tradition... hopefully in September when it's a bit warmer... :^)
There were well over 50 coilers and their spouses in attendance. Lots of 
Tesla coils, a rail gun (with a successful first full power firing), and 
even a machine that fused sand into fulgurites using high current high 
voltage.

John, the tube that came out of the welder was most likely a thyratron 
(the vacuum tube equivalent of modern day SCR's or thyristors). 
Thyratrons are gas filled "triodes" that are designed to control AC 
power going to a timed/pulsed welder. Various gases are used in 
thyratrons, including hydrogen/deuterium, xenon, or mercury vapor. The 
type of thyratrons you saw were most likely slow, high current mercury 
vapor thyratrons, used to control AC power into the welder.

Larger welding systems used higher power tubes called ignitrons. 
Ignitrons use a pool of mercury as the cathode, a massive graphite 
anode, and a dense mercury vapor arc discharge (triggered by a high 
current pulse into an igniter electrode) to control large amounts of 
power. They were also used as high current rectifiers for high current 
DC welders. Unfortunately, neither type of tube is useful in modern day 
Tesla Coiling.

Best regards,

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
"Electromagically" (TM) Shrunken Coins!
http://www.teslamania-dot-com

Tesla list wrote:
> Original poster: "John Richardson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jprich-at-up-dot-net>
> 
> Hi Guys,
>  
> Well, Resonance Research's Teslathon was a huge success.  Lots of awesome
> stuff, and a good time for all.
>  
> I was highly impressed by Steve Wards VTTC, and it's given me the bug to
build
> one.  I'm not all that knowledgeable with electronics, but I have a question
> that I'm hoping someone can help me with:
>  
> In an old welding shop one day, and one of the guys was holding the largest
> tube that I had ever seen.  I seem remember that he said it was out of an old
> DC welder, or maybe it was from some huge antique battery charger.  Is anyone
> familiar with one of these, and would it have any practical application in
> building a VTTC?  It seems that everyone is worried about overdriving their
> plates, and common sense would dictate that a rectifying tube of this type
> would be nearly indestructible.  Am I dreaming, or is it possible that
this has
> some relevance?
>  
> Thanks,
>  
> John Richardson
> 
> 
> 
>