Re: [TCML] Re:Pros and cons

[futuret@xxxxxxx]

 I see.  I wasn't really following this thread.  I agree the resonant frequency is
important for VTTC's but somehow I can't imagine a frequency below 50kHz
causing insulation problems.  Has that problem been demonstrated in a 
VTTC?  Certainly if too-thin wire is used, that might cause a problem.
A 50kHz VTTC should be constructed physically large with a large
substantial toroid perhaps, to help keep the frequency low, and to permit
adequate insulation.  A 50kHz VTTC would probably tend to be a rather
powerful VTTC in keeping with the physical size.  

For whatever reason, I tend to obtain fuzzy looking sparks at the lower
VTTC frequencies below 200kHz or so.  Fuzzy sparks may not be as
long as the more sword-like or spike-like sparks, which are more likely
to appear between 200 to 400kHz or so.     

Regards,
John

 

 

-----Original Message-----
From: Dex Dexter <dexterlabs@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tue, Dec 15, 2009 3:24 pm
Subject: Re: [TCML] Re:Pros and cons


But,the question here isn't how long arcs can tesla transformer
(of any type) generate for optimum BPS rates and fixed powers.
The question is rather how long arcs tesla transformers can generate
given  output voltages and resonant frequencies!
I asked the question before for aprox 100 kV output and nobody knew
to answer (except Dr.R who suggested lenghts around 4 ft).

At least I found the material relevant for VTTCs below 100 kV and 500 kHz. 

See here:
http://i567.photobucket.com/albums/ss118/dexdex666/p124-125.jpg
http://i567.photobucket.com/albums/ss118/dexdex666/hfgaps.jpg

Do you see why is operating frequency important for VTTCs?
I guess the most "voltage efficient"  VTTC frequncy is between 200 kHz and 400 
kHz.
In VTTC coiling higher frequencies (>500 kHz) are not desirable 
becouse the coil parts start to consume more power (overall efficiency drops)
,and frequencies below 50 kHz develop too high output  voltages causing coil
insulation problems.

For SGTCs or DRSSTCs I have got no clue except the resonant frequency is
less important.

Dex     

       
--- futuret@xxxxxxx wrote:

From: futuret@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: Re: [TCML] Re:Pros and cons
Date: Tue, 15 Dec 2009 14:16:08 -0500


 Steve, Dex,

I'm thinking that a coil which has a rather small bang size for the physical 
size
and toroid size, may need a higher break rate for best results, just to bring it
into the sweet spot.  At low break rates, the spark may be barely breaking
out, and barely coalescing, etc.  I do think that large coils tend to be 
somewhat
more efficient in general.  It would be interesting to greatly increase the bang
size of Greg's coil, and then see what breakrate is best, and if the spark
length still grows well with increases of breakrate.  The toroid size is a 
factor
in these issues too.  Once the spark length reaches 3 or 4 times the toroid
diameter, the sparks have a much harder time growing longer.  With a small
bang size, a higher breakrate is needed to grow the spark to 3 or 4 times
the toroid diameter.  At that point the spark length is maxing out pretty 
much anyway, based on toroid size.  Much of what we see regarding
the performance of coils at various breakrates may have a lot to do with
the toroid diameter.  For example if the bang size of Greg's coil was 
greatly increased, then his coil would probably give long sparks at a
much lower breakrate.  Then if the breakrate was increased, the sparks
might not grow very much.  However if a much larger toroid was installed,
then the spark length would again increase more as the breakrate was
increased.  It's a matter of matching the input power to the toroid size
basically (within some acceptable range of breakrates).  In a totally
optimized system, a lower breakrate around 120 to 150 bps is probably
still best.... at least that's my guess.   

Regards,
John

 

 


 
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