Re: Mini OLTC is getting 9"

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

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Steve,

Wow cool!!

Same hot mean sparks as mine.  Interesting that you have so much control 
over BPS!  Does it make any difference??  With the OLTC being so highly 
controlled otherwise, you should be able to tell if say 120 bps is any 
better or worse than say 600 BPS...  That is a very old question that maybe 
you can study!

I have not gotten my OLTC written up this winter like I was sposta do (BAD 
me!!)...  I still have not run it off 240 either.  The big lab still does 
not have 240 available...

Wonderful to know that there are now two!!  I bet you don't miss the big 
transformers (not knowing how big your DC supply is).  So far the best 
things about OLTCs is not high voltage transformers and the circuits are 
conventional and relatively easy to play with.  Looks like we have to work 
on the spark length stuff.  I think your going to a smaller coil is a great 
idea.

I do note that for a given power we seem to be getting about the same type 
and length of streamers even though the frequency is 4X different.

http://hot-streamer-dot-com/temp/OLTC08-25-06.jpg

We don't know what all goes into making short or long streamers.  But new 
data is coming in ;-))

Cheers,

         Terry

At 11:39 PM 3/15/2003 +0000, you wrote:
>Hi guys,
>
>I just got my mini Off-Line Tesla Coil finished. Now that it has a proper 
>power supply, it runs at 1200bps and produces 9" hot arcs to ground. It's 
>been an interesting project and kind of ties in with what Dan "Captain 
>Corona" McCauley was saying about the SSTC hybrid thing. Current is free 
>but you pay for voltage etc.
>
>The OLTC is kind of crippled by being restricted to about 700V primary 
>voltage. You need a very large tank cap to get a reasonable bang size, so 
>you have to use a one-turn primary and also a secondary with low resonant 
>frequency, which means the secondary is physically large, so it has lots 
>of self-capacitance and therefore a low top voltage and poor streamer 
>growth. It also means the primary current is massive to the point that it 
>isn't free any more. My coil runs 900 amps peak and the IGBTs get pretty 
>hot as you would expect. They're probably about 60% efficient.
>
>I put some spark pics from the OLTC as well as a quicktime movie on my 
>website:
>
>http://www.scopeboy-dot-com/tesla/t3sparks.html
>
>Steve C.
>