Re: [TCML] Spark gap Resistance

[FutureT@xxxxxxx]

In a message dated 11/20/2007 9:17:59 P.M. US Eastern Standard Time,  
list@xxxxxxxxxxxxxxxxxxxxxxxxx writes:

>But is the spark gap "really" a loss.... IGBT can turn off whenever  you 
>want, though *IF* you could turn off the spark gap just as fast,  then what 
>would be the results then ?


Chris,
 
Yes, the spark gap is really a loss.  Even if the gap could turn  off
as fast as an IGBT, the spark gap would still have higher losses.
 
 
>Tight coupling is where you get this "double hump problem" I saw some  data 
>on this ( TCBA news maybe) it looksed to me like a lower coupling  would be 
>better, though the frequency range seemed to be a lot  narrow..
 
 
The double hump is not actually a problem.  Malcolm showed this  in
his excellent analysis a number of years ago.  



> Use as large of a dia secondary coil as practical,  typically around 10 to 
> 20 inch dia range, to obtain max. sec  potential.  This also helps keep the 
> res freq low while helps  the IGBTs switch more efficiently.  They are 
> rated at 75 kHz,  but operate more efficiently below 50 kHz.
>

>I read  (  in CSN I think) that resistance was more of a factor than 
>inductance  for getting long sparks. I do not think anyone even considers 
the  
>resisitance of the coils  and just goes for high inductance all  the time ?
 
Terry Fritz did a lot of simulations and other work a few years ago  in
which he looked at resistance losses in the primary and secondary.   

>I also have a second ponder ( getting off topic a little ) that  Tesla said 
>the large toroid is only there to counteract the large  inductance.. While I 
>gave up a few weeks ago trying to work that one  out, It sounds to me like 
>Tesla says use a small dia toroid, and get  the coil resistance down to 1 
ohm 
>or below. Maybe use a larger dia  tube to get the inductance as high as 
>possible... Though I think  resistance increases pretty much at the same 
rate 
>as inductnace  does... which makes it pointless and just forces the use of a 
>large  toroid for no reason.....
 
Large toroids are important for long sparks since they store charge  and
help the growth of sparks.  The effects of various toroid sizes are  well
known.  It's possible to get long sparks with a small toroid (or no  toroid)
by using tremendous power levels such as Bob Golka did in project  Tesla.
Needless to say it's not efficient.  
 
Yes, wide secondaries tend to be very efficient, and permit fewer
secondary turns and thicker wire to be used giving lower resistance  and
higher Q (lower losses).  
 
John


>Chris









**************************************Check out AOL's list of 2007's hottest 
products.
(http://money.aol.com/special/hot-products-2007?NCID=aoltop00030000000001)
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla