Re: Simulation of a conventional Tesla coil

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

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

Hi Ken,

I have been catching up on your recent posts.  I was not able to follow in 
real time but I just went through them.

I think the URL for the SiMetrix program is:

http://www.catena.uk-dot-com/Pages/download.html

One little correction, the coil's top terminal voltage (Probe1 NODE) should 
be taken on the other side of the 220k resistor instead of between the 
resistor and 5pF cap.  Probably does not make much difference.

Another thing that is maybe real important is the spark gap loss.  I 
normally put the spark gap resistance at 2 to 3 ohms.  That looses a LOT of 
power but I think it is realistic.  The spark gap loss may have been a 
serious problem in you single/double turn Marx coil configuration.  The 
loss in all those gaps may damp the coil's resonance into oblivion.  But I 
am not sure about say 4000 amp gaps and what the losses are then, but I bet 
they are high.

One reason that I thought the OLTC could work in the first place is that 
these big IGBTs can switch the currents with very low loss.  Far less loss 
than any spark gap.  I and Steve report that our IGBTs only get a little 
warm so the losses are far less than if there were a spark gap there.  If 
spark a spark gap were used on my OLTC, the loss (like 2 ohms) would 
completely kill the resonance since the loop impedance now is only 0.10 ohms!

Neat that you are having so much fun with the simulators!  It really is 
cool and a great help to be able to "test" things with a computer.  It is 
also fun to try "faults" like a cap suddenly shorting or the streamer 
hitting the primary (that does not do much ;-)).

Cheers,

         Terry

At 02:47 PM 5/17/2003 -0700, you wrote:
>Still playing with Newbury Tech's SIMetrix, and pleased with my notion
>for using their "transformer" backward, I've come up with
>http://hot-streamer-dot-com/temp/conv-tc.sxsch,
>http://hot-streamer-dot-com/temp/conv-tc.sxsch.pdf and
>http://hot-streamer-dot-com/temp/conv-tc-grph.pdf.  Newbies & others alike
>might want to go to www.newburytech-dot-com and download a free version of
>SIMetrix.  You can then put the .sxsch file into its Work folder, run it,
>and play with it yourselves.  Generate 500,000 volts with the click of a
>mouse-button!
>
>If you have the cash, buy SIMetrix; I believe it's about $1000.  If I
>were gainfully using it, I would.
>
>You can view the schematic and the first few cycles of primary current
>and output voltage from the pdf files using Acrobat.
>
>This may be old-hat to spark-gap regulars but since I've been
>(masochistically) into solid-state, I've perhaps missed it.
>
>SIMetrix is so much easier to fathom than MicroSim's kludge that I can't
>believe it.  It also now incorporates another simulation program
>(licensed from someone else) which I haven't tried out.
>
>Ken Herrick