Re: Efficient Tesla Coil

 -=> Quoting Nikola Tesla Aka Chip At to Tesla List <=-

 NTAC> TAC> Message-ID: <9502141530.AA22073-at-grendel.objinc-dot-com>
 NTAC> Newsgroups: tesla.list

 NTAC> From richard.quick-at-slug-dot-org Tue Feb 14 01:15 MST 1995
 >Received: from uustar.starnet-dot-net by csn-dot-net with SMTP id AA05760
 NTAC> (5.65c/IDA-1.4.4 for <tesla-at-grendel.objinc-dot-com>); Mon, 13 Feb 1995
 NTAC> 18:22:15 -0700
 NTAC> From: richard.quick-at-slug-dot-org (Richard Quick)
 NTAC> Subject: Efficient Tesla Coil
 NTAC> Date: Mon, 13 Feb 1995 23:51:00 GMT
 NTAC> To: tesla-at-grendel.objinc-dot-com
 Dan> The secondary will be topped with a 20" across,
 Dan> 4" cross-section, toroid. The toroid serves several
 Dan> functions. First, the toroid protects the secondary
 Dan> windings. (How does that work again?) Second, the
 Dan> toroid acts as a capacitance at the resonant frequency,
 Dan> overriding the secondary's internal capacitance, allowing
 Dan> more current flow. Third, the toroid inhibits discharge
 Dan> from the secondary, allowing power to build to high levels  
 Dan> before sparking occurs. Finally, the toroid acts as an      
 Dan> electron (charge-wave) accelerator by not allowing slow-    
 Dan> down of the electrons (charge-wave) as they leave the       
 Dan> flux-propulsion area :) The toroid then is acting as a huge 
 Dan> attraction-potential, which aids resonance, as relative     
 Dan> speeds are maintained as constants, (if not actual          
 Dan> accelerations.)

 NTAC> I will let Mark Graalman respond to this, he definately had a
 NTAC> better hand on this. Mark care to comment?
 MG> A 20"x4" torus sounds pretty good for this power level. Yes the torus
 protects the top winding by stopping the corona that would occur there if
 no terminal capacitance were used. As I said before there is a SMALL amount
 of capacitance between each turn in the secondary and this prevents corona
 from developing "inside" the coil, I.E. between the windings. The top turn
 of the coil has no turn above it to shield it for corona and thats were the
 terminal comes into play as far as stopping the corona at the top winding.
 But if the terminal is too high, there will come a point where this 
 protection won't occur and corona will return to some extent.

 The terminal acts as ADDTIONAL capacitance to the secondary and if you've
 noticed, the output of a Tesla coil is "hungary" for capacitance, I.E. if
 you throw a wrench or other metal object passed a running coil the
 discharge will strike the object even though its not connected to ground,
 this is because it is addtional capacitance. The toroid acts to store the
 energy in the secondary system rather than the capacitance of the secondary
 coil itself. I have found in my work that the MINIMUM size for a terminal
 capacitance is what ever size when added to the secondary would cause the
 coils frequency to drop to .707 of the freqency the coil resonanted at 
 before the terminal was added provided enough input power is used. This
 is the point were the terminal capacitance is EQUAL to the distributed/
 stray capacitance within the secondary coil itself. I've found again, if
 enough input power is used, the BEST amount of terminal capacitance is
 the amount that would cause ACTUAL 1/4 wave resonance in the secondary
 winding, I.E. a coil wound with 1800 feet of wire may resonant at around
 230 to 250 Khz.with no terminal on top, but the WIRE in the secondary
 is a physical 1/4 wave at about 130 Khz. If a terminal is added to this
 coil that would result is ACTUAL 1/4 wave resonance in the secondary or
 in this case about 130 Khz, I believe at this point, ALL internal 
 capacitance of the secondary windings has been absorbed by the terminal
 and then the secondary system can be treated in a lumped constant format.
 This is the size of toroid I run in my system and it results in only ONE
 discharge comming off the secondary thats VERY THICK, LOUD, and LONG and
 it actually looks like its "pouring" off the terminal. Also at this point
 the amount of power the secondary coil can tolerate is considerable.

                                Mark Graalman

... Alias, Mark the spark
___ Blue Wave/QWK v2.12