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aug-94.txt



  Date: 07-30-94  16:27
  From: Don Kimberlin                               
    To: Richard Quick                               
  Subj: Tesla Coils
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...Nice sketch:

RQ>                  60Hz Line In
RQ>               |                |
RQ>               |                |
RQ>               +----UUUUUUUU----+
RQ>                ----------------    X1
RQ>               +UUUUUUUUUUUUUUUU+
RQ>               |       |        |
RQ>               |      -+-       |
RQ>               |     ///        |
RQ>               U||            ||U
RQ>          RFC1 U||            ||U  RFC2
RQ>               U||            ||U
RQ>               U||            ||U
RQ>               |                |
RQ>               |                |
RQ>               +------O  O------+
RQ>               |       G1       |
RQ>               |                |
RQ>              -+-               |
RQ>           C1 -+-               |
RQ>               |                |
RQ>               |         L2     |
RQ>               +UUUUUUUU--------+

RQ>           =+---UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU-----T T1
RQ>                      L1

...but where do you plug the microphone in? <smirkle>

 ! Origin: Borderline! BBS Concord,N.C. (704)792-9241  (1:379/37)
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  Date: 02 Aug 94  17:47:00
  From: Richard Quick                                
    To: Don Kimberlin                                
  Subj: Tesla Coils
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 -=> Sez Don Kimberlin to Richard Quick <=-
 DK> ...Nice sketch:
 DK> ...but where do you plug the microphone in? <smirkle>

     Human voice               T1
        \/                     
                               
     꼼컴쩡컴<--Diaphram             L2                         
       V   <--Valve         쳐컴컴컴}                         
                                   }                         
 袴袴鳩솬뷔賽                         }                         
Gas in^                               }                         
Gas out>                              }                         
                           A1         } L1  C1                  
         훤袴袴袴袴袴袴袴袴 >>>>       } {컴캑쳐컴쩡컴 < HF      
            Gas stream>                } {        o              
                                       } {     G1 o              
                                       } {컴컴컴컴좔컴 < HF      
                               쳐컴컴컴}                         
                                                                 
                       earth  拙                                 
                                                                  
The "gas under pressure" microphone was placed in the circuit
between the air capacity terminal (T1) and the ground. The
modulated air stream would in turn modulate the arc at A1. 
L2 is the Tesla secondary, L1 is the primary coil, C1 is the
primary capacitance, G1 refers to a high speed rotary break. 
The power supply for this particular circuit was a high 
frequency CW alternator.                                          
    
This was only the first of many successful voice modulation
transmitting devices used by Tesla in Colorado Springs and noted
in June of 1899 (he had multiplexing already patented). Before I
would take time to diagram his carbon microphone transmitters and
receivers I would suggest you see: COLORADO SPRINGS NOTES
1899-1900, Nickola Tesla, published by NOLIT, 1978 Beograd,
Yugoslavia, pp34-36... <smirkle> 

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  Date: 08-03-94  11:56
  From: Dave Halliday                               
    To: John Marsh Iv                               
  Subj: Tesla Coils
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JM|I tried following the discussion on tesla coils and even
  |downloaded a packet of messages someone created and I think I  
  |came in to the conversation too late.  Could some one explain  
  |to me the exact building of a tesla coil (like instructions),  
  |like I was stupid.  I know about electronics, but I haven't    
  |ever built a tesla coil and need some help, I know I need a    
  |HUGE capacitor, but what else?

Hi John - actually the value of the capacitor is pretty small -
it just has to be of a very very high working voltage - remember
that you are putting several tens of thousands of volts through
it...

Basically, what you are building is a resonant step-up
transformer.

Your primary circuit consists of a high-voltage source ( greater
than 10KV at about 30 Milliamps ) fed to your resonant circuit
through a spark-gap.

The spark-gap provides the intermittant interruption of the
high-voltage source that allows the coil to oscillate at a much
higher frequency than your incoming house current ( 300-600 KHZ
as opposed to 60 Hz ).

Your secondary coil is made to be resonant at the same high
frequency and it has two features - an incredibly solid ground on
the bottom end and some form of capacitive loading ( a ball or a
torroid "hat" ) on the top end.

For grounding, I am using three 10' long copper plumbing pipes
stuck into my yard at 5 foot intervals.  For the power I will be
running, this will be a marginal ground!

Anyway, re-read the posts, send $10 off to Richard Quick for his
video ( very well worth it! ) and start building! TTYL - Dave
 (206) 528-1941 (1:343/210.0)

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  Date: 08-04-94  11:36
  From: Don Kimberlin                               
    To: Richard Quick                               
  Subj: Tesla Coils
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RQ> -=> Sez Don Kimberlin to Richard Quick <=-
RQ> DK> ...Nice sketch:
RQ> DK> ...but where do you plug the microphone in? <smirkle>

RQ>     Human voice               T1
RQ>        \/                     
RQ>                               |
RQ>     #---+---#<--Diaphram      |       L2
RQ>     # | V   #<--Valve         +--------}
RQ>     # | |   #                 |        }
RQ> ----+-+#|####                 |        }
RQ>Gas in^  |                     |        }
RQ>Gas out> |                     |        }
RQ>         |                  A1 |        } L1  C1
RQ>         +------------------ >>>>       } {---++---+--- < HF
RQ>            Gas stream>        |        } {        o
RQ>                               |        } {     G1 o
RQ>                               |        } {--------+--- < HF
RQ>                               +--------}
RQ>                               |
RQ>                       earth  ===

RQ>The "gas under pressure" microphone was placed in the circuit
RQ>between the air capacity terminal (T1) and the ground. The
RQ>modulated air stream would in turn modulate the arc at A1.
....

...Sonofagun!  Old (young) Tesla had it all!  Interesting
situation occurs when trying to modulate extremely low
frequencies, however. Unless the ratio between the modulating
(speech) and modulated (radio) sigs is more than about 1:10, a
lot of problems with distorted speech occur.  Still, if the
technology had ever gotten to wide use, I'm sure he would have
worked that out.... (704)792-9241  (1:379/37)

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  Date: 07 Aug 94  22:31:52
  From: Richard Quick                                
    To: Don Kimberlin                                
  Subj: Tesla Coils
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 RQ> DK> ...Nice sketch:
 RQ> DK> ...but where do you plug the microphone in? <smirkle>
 
     Human voice               T1
        \/                     
                               
     꼼컴쩡컴<--Diaphram             L2                         
       V   <--Valve         쳐컴컴컴}                         
                                   }                         
 袴袴鳩솬뷔賽                         }                         
Gas in^                               }                         
Gas out>                              }                         
                           A1         } L1  C1                  
         훤袴袴袴袴袴袴袴袴 >>>>       } {컴캑쳐컴쩡컴 < HF      
            Gas stream>                } {        o              
                                       } {     G1 o              
                                       } {컴컴컴컴좔컴 < HF      
                               쳐컴컴컴}                         
                                                                 
                       earth  拙                                 
 
 RQ>The "gas under pressure" microphone was placed in the circuit
 RQ>between the air capacity terminal (T1) and the ground. The
 RQ>modulated air stream would in turn modulate the arc at A1.
 DK> ....

 DK> ...Sonofagun!  Old (young) Tesla had it all!  Interesting
 DK> situation occurs when trying to modulate extremely low
 DK> frequencies, however. Unless the ratio between the           
 DK> modulating (speech) and modulated (radio) sigs is more than  
 DK> about 1:10, a lot of problems with distorted speech occur.  

Tesla mentions this effect several times in the COLORADO SPRINGS
NOTES, both in reference to the circuit above, and in the carbon
microphone circuits. He stated that the oscillations of the coil
and the break rate on the gap had to be very rapid to reduce this
effect and produce the clearest speech at the receiver; so it
appears to me at any rate, that he was not only very aware of
this problem, but that he had gone far towards solving it.

 DK> Still, if the technology had ever gotten to wide use, I'm    
 DK> sure he would have worked that out...

I think it was worked out. So many people fail to realize that
Tesla designed and constructed not random inventions, but entire
working systems. By "working systems" I mean things like the
commercialized polyphase system in use today (and unchanged since
Tesla first handed the patents to Westinghouse machinists).

Tesla stated all the way up to the time of his death in 1943 that
his wireless system was far superior to any system in use. The
example above is drawn from his experimental work of 1899 and
prior, as are the carbon microphone systems I mentioned (and
provided references for). What I find particularly impressive:
his system required no sensitve detector (receiver - amplifier),
and no external power supply, for a person to hear human voice at
the receiving end (the transmitter being very powerful and
efficient at delivering energy). 

Tesla showed us fully developed triode vacuum tubes in 1891 in
his public lectures (drawings, photos, and lecture transcriptions
of the tubes exist). He was asked during his pending court case
in 1916 why such tubes were not employed by him in receiver/
amplifier circuits. He answered that in his "system" they were
not required: that no amplification was. He was clearly quite
familiar with the design, construction, and operation of these
tubes before Deforest; but did no further study with them because 
the knowledge and use of these tubes were not required for voice
transmission. 

Tesla frustrates me time and time again for what he clearly
documented but refused to employ/patent in some application;
others grabbed credit for much of what was his original work. 

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  Date: 08-07-94  14:30
  From: Mark Logsdon                               
    To: Richard Quick                              
  Subj: Tesla Coils 
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RQ> Quenching typically relies on one or more techniques. The 
RQ> most common method used is expending the arc out over a 
RQ> series of gaps. Gaps of this type are know as "series static
RQ> gaps". "Static" in this use refers to the fact that the gap
RQ> is not actively quenched. The plasma is formed in several 
RQ> locations, and the voltage at each gap is lowered as more 
RQ> electrodes are placed in series. Heat, hot ions, and voltage
RQ> are distributed. As the tank circuit loses energy to the 
RQ> secondary coil, the voltage and current in the tank circuit,
RQ> and likewise across the series of gaps, drops to the point
RQ> where the arc is no longer self sustaining. The arc breaks,
RQ> and the capacitors are allowed to recharge for the next 
RQ> pulse.                                           

Isn't this the technique employed on automotive ignition systems? 
I have found that there is the gap in the spark plug and a gap
inside the ignition module. 317-882-5575, 882-4471 (1:231/875)

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  Date: 09 Aug 94  20:47:59
  From: Richard Quick                                
    To: Mark Logsdon                                 
  Subj: Tesla Coils, gaps
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RQ> Quenching typically relies on one or more techniques. The 
RQ> most common method used is expending the arc out over a 
RQ> series of gaps. Gaps of this type are know as "series static
RQ> gaps".              

 ML> Isn't this the technique employed on automotive ignition     
 ML> systems?  I have found that there is the gap in the spark    
 ML> plug and a gap inside the ignition module.

While automotive ignition systems do bear some relation to Tesla
patented domain (the car distributor is a synchronous rotary
spark gap) there is really no need to quench an automotive
ignition. Automotive ignition circuits do not produce the high
current pulses and the associated high temperature plasmas
typical of the Tesla tank circuit - main system spark gap. 

Since the automotive ignitions are not producing high current
pulses, nor high temperature plasmas; my guess would be that 
the rotary break (distributor rotor and cap), and the points/
sensor, are more than sufficient by themselves to regulate the
timing and duration of the spark at the plug. The spark plug
gap is designed to ignite the fuel/air mixture in the combustion
chamber, a far cry from the gap function in a coil.

It is difficult perhaps to truly relate to the Tesla spark gap,
even on a very small coil, without having actually messed with
one. The main system spark gap in a Tesla coil is required to
handle peak powers of many killowatts (very small coil) and
megawatt, even gigawatt peak powers in medium and large coils.

The arc is very thick, bright blue/white in color, and UV rich.
Even on a tabletop coil system, the plasma channel formed when
the gap breaks down is going to be several millimeters in
diameter. On moderately powered coils, say 1.5 killowatts of
input power from a couple of 12 kv 60 ma neon sign xfrmrs, the
plasma channel formed at the main system spark gap is about as
thick as a pencil; this is not the quietly buzzing yellow/orange
arc of a Jacob's Ladder... We are talking about a brilliant blue/
white arc like that of a steel cutting flame. I guess I could add
here that unlike the soft squeeling of the oxy/steel cutting
flame, the pulsing nature of the arc across the spark gap on even
a moderate sized coil is loud enough to require hearing
protection and/or muffled enclosures; enclosures and shielding
being recommended anyway to prevent UV burns to the eyes and skin
as well as to allow ducting/ventilation for ozone and NOx gasses.
On larger coils the rotary gaps spray molten slag as they
vaporize the tungsten electrodes and suntan your retnas...

Can you understand the difference now? The typical automotive
ignition gives a cold, thin and spindly (threadlike), violet
colored spark at the gap. Ignition systems require no quenching.

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  Date: 08-07-94  01:58
  From: Alexander Schek                            
    To: All                                        
  Subj: What is Tesla?
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HI there !

I am new in electronics and I wonder what a "Tesla" is... any
help ? (562) 204 8361  (4:880/21)

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  Date: 10 Aug 94  16:30:38
  From: Richard Quick                                
    To: Alexander Schek                              
  Subj: Tesla?
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 -=> Sez Alexander Schek to All <=-

 AS> I am new in electronics and I wonder what a "Tesla" is...    
 AS> any help ?

Nickola Tesla was the Yugoslavian born American immigrant
(Midnight July 9-10, 1856 - 10:30 PM January 7, 1943) whose
inventions and patented domain include: 

Rotating magnetic field (alternating current induction motor), 
60 cycle polyphase power generation and transmission system
(modern power grid), radio (US Supreme court overturned Marconi &
Co. patents in his favor 1943), waveguide, synchronous rotary
spark gap (distributor), electron microscopy, RF transformers,
inductive and base fed resonate structures (Tesla Coil, flyback
transformer, wireless power transmission), co-inventor of X-Rays
(Roentgen credited him), mechanical and electrical oscillators.
The list goes on and on; the US Patent office issued him over 160
patents.

The "Tesla" is a unit of magnetic flux density in the SI and mksa
electromagnetic systems named after the great unsung inventor.

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  Date: 08-06-94  17:00
  From: Tim Knights                                 
    To: Don Kimberlin                               
  Subj: Re: Tesla Coils
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What the H-at--at--at- is a Tesla coil?   (1:2240/176)

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  Date: 10 Aug 94  16:05:13
  From: Richard Quick                                
    To: Tim Knights                                  
  Subj: RE: Tesla Coils
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 -=> Sez Tim Knights to Don Kimberlin <=-

 TK> What the H-at--at--at- is a Tesla coil?

> Imported from Archives 12/06/93

 JF> For those of us who are wanna bees, What's a tesla coil...?

A Tesla Coil is an air core, RF resonate, transformer. It is a
very efficient source of very high voltage RF energy. 

Basically you take a high voltage pulse discharging capacitor and
connect it to a large heavy coil. The cap is charged with a high
voltage power supply (neon sign xfrmr, potential xfrmr, or power
distribution xfrmr run backwards). The circuit consisting of the
cap and coil is excited by discharging the cap through a spark
gap. This way current of hundreds of amps at thousands of volts 
are made to oscillate through the coil. Frequency of oscillation
is dependant on the number of turns in the coil and the size of
the cap. This is the basis of the Tesla Tank circuit.

The secondary coil or "Tesla coil" is a hollow form wound with 
several hundred turns of wire in a single layer. This coil has a
natural RF resonate frequency based primarily on the length of
wire used in the winding. The tank circuit frequency is made to
match the secondary natural frequency by tuning: changing the
number of turns in the heavy primary coil or changing the value
of the pulse discharging capacitor. When the tank circuit freq-
uency is matched to the secondary frequency, and the coils are
placed in close proximity, energy is exchanged and transformed.

RF voltages in the megavolts can be achieved with very high
efficiency. The tank circuit literally converts line current into
a series of rapid pulse dicharges with peak powers typically in
the megawatt range. A simple coil setup is capable of producing
what to the eye are continous spark discharges several feet in
length, or longer. 

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  Date: 08-08-94  15:56
  From: Terry Smith                               
    To: Don Kimberlin                              
  Subj: Tesla Coils
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RQ>              -+-               |
RQ>           C1 -+-               |
RQ>               |                |
RQ>               |         L2     |
RQ>               +UUUUUUUU--------+

RQ>           =+---UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU-----T T1
RQ>            
         L1

 DK> ...but where do you plug the microphone in? <smirkle>

Dunno, but doesn't T1 go to the late night announcer's seat?   

<g> Terry  (203)732-0575 BBS (1:141/1275)

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  Date: 08-08-94  15:25
  From: Terry Smith                                
    To: Richard Quick                              
  Subj: Tesla Coils
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RQ>        PC1     X1       RFC 1A       RFC 2A
RQ> --------+------+|+------UUUUU---+----UUUUU---> TO TESLA TANK
RQ>        -+-     )|(              |
RQ>        -+-     )|(              |
RQ>         |      )|(              O
RQ>    .+---+      )|(        .+----o SAFETY GAP
RQ>         |      )|(              O
RQ>        -+-     )|(              |
RQ>        -+-     )|(              |
RQ> --------+------+|+------UUUUU---+-----UUUUU---> TO TESLA TANK
RQ>        PC2              RFC 1B        RFC 2B

 RQ> "Protective Capacitors PC1 and PC2 are not critical and can  
 RQ> be rated in the vicinity of .5 to 2 microfarads. Use a       
 RQ> voltage

One little point of safety, which should be pointed out to the
folks with limited electronics safety knowledge, is that PC1 and
PC2 would have to be NO HIGHER than 0.1 uFd, in order to meet a
5mA ground current leakage standard. The circuit and values of
PC1 & PC2 shown above could be lethal if the building ground
connection were marginal or missing.  

Obviously that would decrease filtering effectiveness.  A 120 V
isolation xfmr, or additional stages to add both filtering and
safety related line isolation, as you later described, would be
possible solutions ot that problem.  BTW, I have seen foolish and
inattentive engineering of power supplies for broadcast equipment
from one reputable and fairly quality oriented manufacter, which
caused 6 and 12 mA of ground leakage with power on and off, due
to similar low cost but irresponsible RF filter cap size choices. 

 RQ> rating as high as possible. The usual 400-600 volt           
 RQ> capacitors will not withstand kickbacks for very long. I     
 RQ> prefer capacitors with ratings of from 2500 to 5000 (or      
 RQ> higher) volts"

What are "the usual"?  Orange drop or block type small leaded
film or mica caps?  I would think that current ratings (which
would be related to ESR, and filter effectiveness) might be more
important than voltage rating, so long as no less than 400-600
volt rated caps were used.  At 450 kHz, the Xc of the range of
caps we're discussing would be 0.1 to 3 ohms, which makes me
wonder if "voltage rating" isn't being substituted for physically
larger cap with higher thermal and current limits?  Such overall
higher rated caps should be more effective as RF filters due to
the same lowered ESR which results from other design parameters
being increased.  

Do you know if smaller cap failures are from voltage punch
through, or if it's really from cooking due to a 3-5 amp
repetitive surge current demand, which small inexpensive caps
can't handle?  

BTW, I'll be Freq'ing your archive tonight.  I'm curious about
what resonant circuits you might have brewed.  Thanks for making
it available! Terry  (203)732-0575 BBS (1:141/1275)

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  Date: 11 Aug 94  17:01:49
  From: Richard Quick                                
    To: Terry Smith                                  
  Subj: Tesla Coils
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       PC1     X1       RFC 1A       RFC 2A
컴컴컴컴쩡컴컴커붚컴컴컴程程粘컴쩡컴쿤程程컴> TO TESLA TANK
       컨     )(              
       컫     )(              
              )(              O
grn曹컴캑      )(    grnd曹컴컴o SAFETY GAP
              )(              O
       컨     )(              
       컫     )(              
컴컴컴컴좔컴컴켸봉컴컴컴UUUUU컴컨컴컴훃UUUU컴> TO TESLA TANK
       PC2              RFC 1B        RFC 2B

 
RQ> "Protective Capacitors PC1 and PC2 are not critical and can
RQ> be rated in the vicinity of .5 to 2 microfarads." 

 TS> ...PC1 and PC2 would have to be NO HIGHER than 0.1 uFd, in   
 TS> order to meet a 5mA ground current leakage standard.  The    
 TS> circuit and values of PC1 & PC2 shown above could be lethal  
 TS> if the building ground connection were marginal or missing. 

Good point, though yours is a worse case scenario. There were
already several reasons why I did not like the circuit above, 
you just added another reason to the list.
  
 TS> Obviously that would decrease filtering effectiveness. A     
 TS> 120 V isolation xfmr, or additional stages to add both       
 TS> filtering and safety related line isolation, as you later    
 TS> described, would be possible solutions ot that problem. 

My improvements on Harry's circuit above work pretty well, and I
have always loved isolation xfrmrs as an additional safety/RF/
spike/surge measure. I am considering the addition of a pair of
back to back pole pigs in my low voltage feed lines for just this
purpose.

 RQ> "Use a voltage rating as high as possible. The usual        
 RQ> 400-600 volt capacitors will not withstand kickbacks for     
 RQ> very long. I prefer capacitors with ratings from 2500 to  
 RQ> 5000 (or higher) volts"

 TS> What are "the usual"?  Orange drop or block type small       
 TS> leaded film or mica caps?  

Again, I am quoting Harry Goldman above, but generally speaking
the "PC" caps used in Harry's circuit are the typical "can" type
caps used in capacitive start motors. I have seen a lot of these
used (and NO they are not filter caps) simply because they are
cheap; surplus caps with a rating of .1 uf -at- 400 vac are locally
available for around $0.25...

 TS> I would think that current ratings (which would be related
 TS> to ESR, and filter effectiveness) might be more important    
 TS> than voltage rating, so long as no less than 400-600 volt    
 TS> rated caps were used.  At 450 kHz, the Xc of the range of    
 TS> caps we're discussing would be 0.1 to 3 ohms, which makes me 
 TS> wonder if "voltage rating" isn't being substituted for       
 TS> physically larger cap with higher thermal and current        
 TS> limits?  

Very possible. 

 TS> Such overall higher rated caps should be more effective as   
 TS> RF filters due to the same lowered ESR which results from    
 TS> other design parameters being increased.

Good point.
   
 TS> Do you know if smaller cap failures are from voltage punch   
 TS> through, or if it's really from cooking due to a 3-5 amp     
 TS> repetitive surge current demand, which small inexpensive     
 TS> caps can't handle?  

I don't know. You could ask Harry Goldman (I have posted his
SNAIL address should you choose to correspond), as he recommended
the above circuit (recently too); I have never used it. But in my
experience voltage punch through has only occurred as a result of
a typical coiling type "incident" where there was no doubt as to
the cause (run away oscillator, direct strike to low voltage feed
lines, xfrmr breakdown, etc..). Perhaps this is what he was
referring to when he said the lower voltage caps don't last very
long. On the other hand a repeated 3-5 amp surge current demand
on the filter implies something else is wrong... perhaps he is
not properly grounded or choke/filtered at the RF side of the
xfmr???  Like I said... I don't know, but I would not recommend
the above circuit.

 TS> BTW, I'll be Freq'ing your archive tonight.  I'm curious     
 TS> about what resonant circuits you might have brewed.  Thanks  
 TS> for making it available!   

Thank you for the intelligent and progressive input. The
TESLA?.ZIP file is not as complete as I would like to see it, but
I feel it is a worthwhile contribution. Please make it available
locally after you grab it. Your input in this thread has been
included in it's entirety in the file, and has been appreciated.

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  Date: 08-11-94  22:24
  From: Mark Logsdon                              
    To: Richard Quick                             
  Subj: Tesla Coils, Gaps
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RQ> ML> systems?  I have found that there is the gap in the spark
RQ> ML> plug and a gap inside the ignition module.                
       
RQ> While automotive ignition systems do bear some relation to
RQ> Tesla patented domain (the car distributor is a synchronous
RQ> rotary spark gap) there is really no need to quench an 
RQ> automotive ignition. Automotive ignition circuits do not 
RQ> produce the high current pulses and the associated high 
RQ> temperature plasmas typical of the Tesla tank circuit - main
RQ> system spark gap.             

OK, I confess:  I was really speaking of gas turbine ignition
systems, which are much higher in energy than that of an
automobile.

RQ> Can you understand the difference now? The typical automotive
RQ> ignition gives a cold, thin and spindly (threadlike), violet
RQ> colored spark at the gap. Ignition systems require no 
RQ> quenching.

An automotive spark makes a "tick tick" sound, but a gas turbine
igniter goes "snap snap."  Maybe that would indicate a need for
quenching.  What do you think?   317-882-4471 (1:231/875)

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  Date: 12 Aug 94  18:11:09
  From: Richard Quick                                
    To: Mark Logsdon                                 
  Subj: Tesla Coils, Gaps
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Mark was wondering if ignition systems required quenching...

 ML> I have found that there is the gap in the spark
 ML> plug and a gap inside the ignition module.                   
    
 RQ> While automotive ignition systems do bear some relation to   
 RQ> Tesla patented domain,, there is really no need to quench an 
 RQ> automotive ignition. Automotive ignition circuits do not     
 RQ> produce the high current pulses and the associated high      
 RQ> temperature plasmas typical of the Tesla spark gap.          
  
 ML> OK, I confess:  I was really speaking of gas turbine         
 ML> ignition systems, which are much higher in energy than that  
 ML> of an automobile.

Much higher.....  Humm..., how much is "much higher"?   
Are we talking an order of magnitude higher? 

Small tabletop Tesla coils have tank circuit currents that start
around 9000 volts at 10 amps. That is a peak power of a measley
90,000 watts, or nearly 1/10th of a megawatt. 
 
 RQ> Can you understand the difference now? The typical           
 RQ> automotive ignition gives a cold, thin and spindly           
 RQ> (threadlike), violet colored spark at the gap. Ignition      
 RQ> systems require no quenching.

 ML> An automotive spark makes a "tick tick" sound, but a gas     
 ML> turbine igniter goes "snap snap."  Maybe that would indicate 
 ML> a need for quenching.  What do you think?

I have no experience at all with turbine ignitions, but I do have
some experience with automotive ignitions, oil burner ignitions, 
and gas ignitions (like a stove or furnace). In all of the
electrical ignition systems I have seen, peak powers of 250 watts
are considered high; more than enough to go "snap snap".

On the other hand a commercial plasma cutter rated at 20,000
watts weighing around 250 lbs. with a three phase input (65 amp
breaker on each phase), is still running peak powers 4.5 times
smaller than a measley tabletop Tesla coil with a single 9000
volt 30 milliamp power supply (8 lbs, 270 watts).

How you might wonder can I get away with such a statement and not
get flamed here? Peak powers of 90,000 watts from a 270 watt neon
sign xfmr???? More than four times the peak power delivered by
the commercial three phase plasma cutter???? 

In Tesla coiling I stress the need for quality high voltage,
plastic film, oil covered, pulse discharging capacitance. This is
the key. Charged with a neon sign xfrmr or other high voltage
power supply, it is pulse discharged to deliver these enormous
peak powers. With a neon sign xfmr the capacitor value is usually
set to fully charge in one half of a cycle: 60 cycle = 120 full
charges (in one second) or ~120th of a second to cycle the
capacitor once. The pulse discharge of this capacitor on the
other hand only takes a few microseconds, thus the peak powers
are amplified to enormous porportions without violating any
conservation of energy (thermodynamics) laws.

What controls this? The spark gap. It MUST quench in order to
deliver these peak powers. A spark gap that does not quench will
cause the arc at the gap to "hang"; peak powers (and tank circuit
efficiency) drop off dramatically.

At the same time a gap that quenches well makes it own work: the
faster the quench time, the shorter the pulse duration, and the
greater the peak power :|: the greater the peak power, the hotter
the arc, the thicker the plasma channel, the more electrode
abalation, the harder to quench (longer pulse duration)...
Vicious cycle, Catch 22, whatever you want to call it.

My example of peak power relationships grows to even enormous
porportions if we increase the current and voltage input into the
Tesla Tank circuit, and increase the capacitor size accordingly.
My figures show that on my really "hot" tank circuit: primary
coil = 100 foot length of 1/2" soft copper water pipe, capacitor
size .05 uf (rated at 90 kvac pulse), input power = 20,000 volts
-at- .5 amp = 10,000 watts rms (half of the plasma cutter). The peak
power at the spark gap easily exceeds 10 megawatts with a tank
current of over 500 amps. Now I am running 50% of the input power
of the commercial plasma cutter, but my peak powers as handled by
the spark gap are rivaling what most communities draw... The
difference is RMS power vs peak power; but at the spark gap in
the Tesla Tank circuit it is a reality (and at the discharge
terminal of the coil system as well). 

So are you telling me that the turbine ignition systems you are
familiar with are running peak powers (or rms powers) over a few
killowatts and require some arc quenching? Do you see any high
voltage pulse rated capacitance used to amplify the peak powers
in the ignition circuit to deliver a hotter arc? If not... there
is no requirement to design a discharge or gap system to quench.  

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  Date: 08-11-94  17:03
  From: Don Kimberlin                              
    To: Richard Quick                              
  Subj: Tesla Coils
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RQ> RQ> DK> ...Nice sketch:
RQ> RQ> DK> ...but where do you plug the microphone in? <smirkle>

RQ>     Human voice               T1
RQ>        \/                     
RQ>                               |
RQ>     #---+---#<--Diaphram      |       L2
RQ>     # | V   #<--Valve         +--------}
RQ>     # | |   #                 |        }
RQ> ----+-+#|####                 |        }
RQ>Gas in^  |                     |        }
RQ>Gas out> |                     |        }
RQ>         |                  A1 |        } L1  C1
RQ>         +------------------ >>>>       } {---++---+--- < HF
RQ>            Gas stream>        |        } {        o
RQ>                               |        } {     G1 o
RQ>                               |        } {--------+--- < HF
RQ>                               +--------}
RQ>                               |
RQ>                       earth  ===

RQ>The "gas under pressure" microphone was placed in the circuit
RQ>between the air capacity terminal (T1) and the ground. The
RQ>modulated air stream would in turn modulate the arc at A1.
DK> ....

DK> ...Sonofagun!  Old (young) Tesla had it all!  Interesting
DK> situation occurs when trying to modulate extremely low
DK> frequencies, however. Unless the ratio between the
DK> modulating (speech) and modulated (radio) sigs is more than
DK> about 1:10, a lot of problems with distorted speech occur.

RQ>Tesla mentions this effect several times in the COLORADO
RQ>SPRINGS NOTES, both in reference to the circuit above, and in
RQ>the carbon microphone circuits. He stated that the oscil-
RQ>lations of the coil and the break rate on the gap had to be
RQ>very rapid to reduce this effect and produce the clearest 
RQ>speech at the receiver; so it appears to me at any rate, that
RQ>he was not only very aware of this problem, but that he had
RQ>gone far towards solving it. ...

...Seems like he ran up against the problem, then, and recognized
it...

[...]

RQ>Tesla stated all the way up to the time of his death in 1943
RQ>that his wireless system was far superior to any system in
RQ>use. The example above is drawn from his experimental work of
RQ>1899 and prior, as are the carbon microphone systems I
RQ>mentioned (and provided references for). ...

...My BIG question:  What records exist describing his *speaking*
on what could be called "radio waves?"  The world credits
Reginald Fessenden with it on December 24, 1906, and if I can
correct that, I'd want to.

RQ> What I find particularly impressive:
RQ> his system required no sensitve detector (receiver - 
RQ> amplifier), and no external power supply, for a person to 
RQ> hear human voice at the receiving end (the transmitter being
RQ> very powerful and efficient at delivering energy).

RQ> Tesla showed us fully developed triode vacuum tubes in 1891
RQ> in his public lectures (drawings, photos, and lecture 
RQ> transcriptions of the tubes exist). He was asked during his
RQ> pending court case in 1916 why such tubes were not employed
RQ> by him in receiver/amplifier circuits. He answered that in
RQ> his "system" they were not required: that no amplification
RQ> was. He was clearly quite familiar with the design, 
RQ> construction, and operation of these tubes before Deforest;
RQ> but did no further study with them because the knowledge and
RQ> use of these tubes were not required for voice transmission.

...I'm not so certain that was a function as much of Tesla's
technology as it would be that the waves Tesla produced are what
we would call "low frequency radio."  At that point in time, all
the big old powerful hogs of spark and alternator transmitters on
low frequency delivered very powerful signals.  Before the world
had more sensitive vacuum tubes, a range of far less sensitive
detectors with names like "coherer" and such were used by
everyone.  It wasn't till after vacuum tubes came around that
people discovered higher frequencies could also be made useful...
they were actually considered useless until the 1920's...and it
wasn't until the 1930's that "shortwave radio" really came into
vogue...the "lowfers" were still in pretty wide use. In fact,
a number are still there today, in several sorts of
applications...

RQ>Tesla frustrates me time and time again for what he clearly
RQ>documented but refused to employ/patent in some application;
RQ>others grabbed credit for much of what was his original work.

...There is no doubt about that.  Any pointers you have to that
first speech on electromagnetic waves by Tesla are appreciated!
(704)792-9241  (1:379/37)
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  Date: 16 Aug 94  11:09:34
  From: Richard Quick                                
    To: Don Kimberlin                                
  Subj: Tesla Coils
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 DK> ...My BIG question:  What records exist describing his       
 DK> *speaking* on what could be called "radio waves?"  The world 
 DK> credits Reginald Fessenden with it on December 24, 1906, and 
 DK> if I can correct that, I'd want to.

Tesla addressed the Franklin Institute in Philadelphia in
February 1893, and the lecture was repeated to the National
Electric Light Association in my hometown, St. Louis, in March
1893. The two lectures employed all of the equipment and elements
of Tesla's radio patents. He operated a spark gap transmitter
and wireless receiver. A large Geissler tube was substituted for
the spark gap in the reciever circuit, and it glowed brightly
when the transmitter was energized. To my knowledge this was the
first time radio was publically demonstrated and all four of the
key tuned circuits were discussed.

 RQ> Tesla showed us fully developed triode vacuum tubes in 1891  
 RQ> in his public lectures (drawings, photos, and lecture        
 RQ> transcriptions of the tubes exist). He was asked during his  
 RQ> pending court case in 1916 why such tubes were not employed  
 RQ> by him in receiver/amplifier circuits. He answered that in   
 RQ> his "system" they were not required: that no amplification   
 RQ> was. 

 DK> ...I'm not so certain that was a function as much of Tesla's
 DK> technology as it would be that the waves Tesla produced are  
 DK> what we would call "low frequency radio."  At that point in  
 DK> time, all the big old powerful hogs of spark and alternator  
 DK> transmitters on low frequency delivered very powerful        
 DK> signals.  Before the world had more sensitive vacuum tubes,  
 DK> a range of far less sensitive detectors with names like      
 DK> "coherer" and such were used by everyone.  It wasn't till    
 DK> after vacuum tubes came around that people discovered higher 
 DK> frequencies could also be made useful... they were actually  
 DK> considered useless until the 1920's...and it wasn't until    
 DK> the 1930's that "shortwave radio" really came into vogue     

Good point, but I think I can also see another perspective. I am
familiar with coherers and other "sensitive devices" used by
early radio pioneers. The range limits of a damped wave
transmitter and the poor quality receiving circuits drove many
early spark gap xmitters to enormous peak powers to get out. Maj.
Edwin H. Armstrong did most of the receiver work that brought
higher frequencies into use, with his development of the
regenerative (or feedback) amplifier circuit, and later the
superhet "beat-note" circuit which forms the basis of most modern
radio and radar reception.

But this still does not account for Tesla's oft repeated
statements that all such systems (from the early low freq spark
xmitters - to modern high freq telcom) are inherently wasteful
and inefficient. Tesla layed it on the line, saying that radio
(regardless of freq) is highly inefficient when looking at the
power broadcast vs. the power received. He stated that radio is
only 10% efficient at best. He compared commercial radio
transmission efficiencies to commercial electrical power
transmission (over 90% efficient to the consumer/receiver).

Yet another way: an omni-directional radio transmitter/antenna is
like setting a candle or bulb on top of a tower. Energy is
radiated all around. If you want to focus and direct the radiated
energy, then the antenna can be modified... for a flame or a lamp
you would put a parabolic refector behind it. But the laws of
radiation mean that the strength of the signal drops off in a
relation to the square of the distance. The energy is disbursed
rapidly, and most of it is lost. To receive a tiny fraction of
the signal at any distance requires some equipment: with the lamp
or flame you would use a lens first, at longer distances you
would use photon amplification. Radio relies on larger, more
powerful and sophisticated, receivers and amplifiers.

What is the efficiency of transmitting alternating currents       
through a wire compared to the efficiency of radiating systems? 
Tesla said that by conduction into the ground and upper
atmosphere he could deliver not only intelligible signal, but
useable power. He realized early on the inefficiency of radiated
signal systems, and focused on a system that employed wireless
conductors instead. 
 
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  Date: 08-12-94  21:37
  From: Jonathan Luthje                           
    To: Alexander Schek                            
  Subj: What is Tesla?
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Gday Alexander,
       if you are referring to a Tesla coil, it is basically a
device which pumps out a whole lot of voltage (via either a
Walton-Cockcroft voltage multiplier, or a transforming coil in a
tower (hence the name Tesla COIL)), and can make some interesting
lightening fX.

The ones i have seen range from a (small) 250kV up to a whopping
2.5MV (Mega-volts), the later of which reqiures a faraday sheild
to keep it "in tow". . . .

any other questions. . . .just direct them here!
Cheers Jon, (13 lines) (3:640/215)
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  Date: 16 Aug 94  12:12:10
  From: Richard Quick                                
    To: Jonathan Luthje                              
  Subj: What is Tesla Coil?
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 -=> Sez Jonathan Luthje to Alexander Schek <=-

 JL> The ones i have seen range from a (small) 250kV up to a      
 JL> whopping 2.5MV (Mega-volts), the later of which reqiures a   
 JL> faraday sheild to keep it "in tow". . . . 

 JL> any other questions. . . .just direct them here!

Sure, what do you recommend as a good spark gap design for the
Tesla Tank circuit?

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  Date: 08-12-94  23:30
  From: Don Kimberlin                              
    To: Terry Smith                                
  Subj: Tesla Coils
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RQ>              -+-               |
RQ>           C1 -+-               |
RQ>               |                |
RQ>               |         L2     |
RQ>               +UUUUUUUU--------+

RQ>           =+---UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU-----T T1
RQ>            L1

TS> DK> ...but where do you plug the microphone in? <smirkle>

TS>Dunno, but doesn't T1 go to the late night announcer's seat?   
TS><g>

...Do you reckon even *that* would keep them awake?  I can
remember plenty of times at 3 AM when those flourescent lights
just hurt my eyes so bad...I think I'll just close my eyes and
rest them for a few mom....zzzzzzzzzz....<bbbbbbbbrrringggg!>
Oh, wow!  What's that?  Darn!  No program audio alarm!  Wow!
look at that automation over there, all the tapes going thwup,
thwup, thwup where they ran right out.  Quick! Grab a music tape
and get it onto one of those drives fast!  (Happens every time!)
(704)792-9241  (1:379/37)

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  Date: 08-11-94  17:05
  From: Don Kimberlin                               
    To: Richard Quick                               
  Subj: Re: Tesla Coils
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TK>What the H-at--at--at- is a Tesla coil?

SET TESLA_QUESTION_DEFLECTION.SYS /on

...over to you, Richard Quick!

...We have the benefit of a real student of Tesla here in
Richard, so let's let him give you that lecture!  (704)792-9241
(1:379/37)
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  Date: 08-15-94  13:28
  From: Mark Logsdon                                
    To: Richard Quick                               
  Subj: Tesla Coils, Gaps
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ML> OK, I confess:  I was really speaking of gas turbine
ML> ignition systems, which are much higher in energy than that
ML> of an automobile.

RQ> Much higher.....  Humm..., how much is "much higher"?
RQ> Are we talking an order of magnitude higher?

A gas turbine has two things working against its starting:  high
pressure ratios, e.g., compression ratios around 15:1, and more
importantly, extremely high air flow.  It therefore requires a
hot spark.  The spark is measured in energy rather than power.  A
typical spark from a turbine ignition system is around three
Joules of energy.


RQ> So are you telling me that the turbine ignition systems you
RQ> are familiar with are running peak powers (or rms powers) 
RQ> over a few killowatts and require some arc quenching? 

All I can say is that there is a spark gap in series with the
igniter plug. 317-882-4471 (1:231/875)

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  Date: 17 Aug 94  12:00:42
  From: Richard Quick                                
    To: Mark Logsdon                                 
  Subj: Tesla Coils, Gaps
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 -=> Sez Mark Logsdon to Richard Quick <=-

 ML> OK, I confess:  I was really speaking of gas turbine
 ML> ignition systems, which are much higher in energy... 

 RQ> Are we talking an order of magnitude higher?

 ML> A gas turbine has two things working against its starting:   
 ML> high pressure ratios, e.g., compression ratios around 15:1,  
 ML> and more importantly, extremely high air flow.  It therefore 
 ML> requires a hot spark....  

 ML> ...there is a spark gap in series with the igniter plug.

Gotcha, and, being the curious type, I checked into this a bit
more.

It appears that the spark gap in the module is employed to
achieve a higher voltage - higher energy (read hotter) spark at
the igniter plug.

If you saved the original post I sent on spark gap technology,
you will see where I discussed, in addition to quenching, another
aspect of gap design having to do with field shape vs. breakdown
voltage. A single spark gap has a very strong electrostatic field
between the gaps which builds as the voltage rises. By adding a
second gap to the system this field strength is greatly reduced.

#1) B+ 컴컴컴컴컴컴컴컴컴컴o o컴컴띱 grnd

#2) B+ 컴컴컴훟 o컴컴컴컴컴o o컴컴띱 grnd

In line section #1, with a single gap between the B+ and the
ground, a very strong electrostatic field is established at the
gap. This gap breaks down with a much lower voltage. To achieve
performance, the gap must be set very wide; too wide for pratical
use with a high energy igniter plug such as we are discussing.

Line section #2 on the other hand, has an insulated section
isolated between two gaps. This section has little or no voltage
impressed upon it by the B+. The breakdown voltage of line
section #2 is much higher than line section #1, EVEN IF THE TOTAL
GAP DISTANCE IN LINE #1 IS AS MUCH AS EIGHT TIMES GREATER THAN 
LINE #2.

That is your answer. It has nothing to do with quenching, it has
everything to do with breakdown voltage.

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  Date: 08-16-94  00:55
  From: Andre Dault                                  
    To: All                                         
  Subj: Building a Capacitor
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Hello there people...   All this talk of Tesla coils is right in
time.. I'm in the middle of building a Telsa Lightning Generator
(tesla coil) But I need some capacitors (big ones) I need .003 -
.005 uF from 15,000 - 25,000 WVDC.. If anyone knows a combination
of capacitors or how I could build one....  It would be greatly
appreciated. Andre Dault  (705) 969-5213 (1:224/90)

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  Date: 21 Aug 94  19:55:41
  From: Richard Quick                                
    To: Andre Dault                                  
  Subj: Tesla coil, cap, 1/2
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 -=> Sez Andre Dault to All <=-

 AD> Hello there people... All this talk of Tesla coils is right  
 AD> in time.. I'm in the middle of building a Telsa Lightning    
 AD> Generator (tesla coil) But I need some capacitors (big ones) 
 AD> I need .003 - .005 uF from  15,000 - 25,000 WVDC.. If anyone 
 AD> knows a combination of capacitors or how I could build       
 AD> one....  It would be greatly appreciated.

... OK, By Request...

The High Voltage, Pulse Discharge,  CAPACITOR, 

Many high voltage projects require a high voltage pulse discharge
capacitor. Whether your project is a laser, Tesla coil, rail gun,
high power taser, or particle accelerator, you will most likely
need a high voltage rated pulse discharging capacitor in your
device somewhere.

Commercial units are expensive. Manufacturers of these units do
not stock them. Each and every unit is built to order. "Off the
shelf" units do not offer the performance required for most high
voltage projects. Off the shelf capacitors get hot, have high
loss to output ratios, and/or will break down in spark excited
tank circuits. Some types are potential explosion hazards.

You can build your own capacitors for these projects from
polyethylene plastic and aluminum flashing.

The following instructions are for a pulse discharging capacitor
with a .02 uf at 35-40 kvdc rating. The unit is rated for work in
spark excited tank circuits with up to 15 kvac rms inputs, 12
kvac is the recommended maximum rms voltage rating, and they will
run all day pulse discharging 10 kvac without getting warm. This
is an ideal unit for small Tesla coils, and may be run in series/
parallel combinations for Tesla coils from desktop size up to 4
kva megavolt coils. The material cost is around $100.00 per unit
as opposed to $150 - $300 for a similar commercial capacitor.

Materials for this unit are as follows:

Three yards of low density, 60 mil, polyethylene plastic.

One ten inch by twelve inch sheet of 1/4" plexiglas. 

One fifty foot roll of 14 inch wide aluminum flashing. 

Eighteen inches of 1 inch schedule 40 pvc pipe. 

Twenty inches of 6 inch PVC DRAIN PIPE. DO NOT USE SCHEDULE 40!

One: six inch pvc DRAIN PIPE END CAP. 

Two: end caps for the 1 inch schedule 40 pvc pipe. The end caps
must have flat bottoms (not rounded) or you will need to cut
them.
 
One gallon of pure U.S.P. Mineral Oil. 

Two: 1/4 x 20 brass machine screws and four nuts.

Two: #8 Pan Head Machine screws with washers and nuts. Screws
should be equal to or less than 3/8ths of an inch long.

Loctite thread fastener (medium strength)

Six or eight: 12" long nylon wire ties

PVC cement (medium body, clear, works best)

PrepSol (Dupont paint store) or U.S.P. alcohol

Four inch stack or clean newspaper or BUTCHERS PAPER

Lint free wipes or good quality paper towels. Don't use the cheap
stuff.
-----------------------------------------------------------------
             BUILDING THE CAPACITOR TANK

Start out by cutting the PVC drain cap in half. You want to cut a
ring 1-1/2" high off of the end cap. The bottom of the end cap
should be saved intact with a 1-1/2" high side wall. 

Lay the ring cut from the 6" PVC drain cap on the sheet of 1/4"
plexi and scribe a circle. Cut the circle out and glue it to the
ring with PVC cement. This forms the clear, see through, lid for
the capacitor tank. When the PVC cement has dried, drill two
holes through the plexi for terminals. The holes should be on
opposite sides of the lid. A small hole is drilled dead center
for venting.

Cut some strips of plexiglas, 3/4" wide by 2" long, out of the
scrap material.

Glue one of the 1" PVC end caps to the inside center of the 6"
PVC drain cap section. Glue at least four of the plexiglas strips
around the 1" end cap. The strips are placed so that they are
flush with the 1" PVC end cap. They should form a "star" pattern
radiating out from the center to form a shelf, 3/4" high, for the
capacitor roll to sit on. This shelf prevents the roll from
resting on the very bottom of the tank, and allows cool oil to
circulate. It is important that there is sufficient room between
the edges of this shelf and the side wall of the 6" drain cap to
allow the 20" section of 6" PVC drain pipe to seat all the way to
the bottom of the end cap. 

When the end cap assembly is dried, glue and seat the 6" PVC
drain pipe in place. Use plenty of PVC cement to prevent leaks.

Once the end cap is firmly seated in the 6" PVC pipe, then cement
the 18" length of 1" PVC pipe down into the center ring. This
pipe saves oil, as well as providing a center post for the
capacitor roll. Glue the second 1" PVC end cap onto the top of
the 1" pipe to seal it. Let the PVC cement dry thoroughly, then
wash the tank out with strong detergent, and allow to dry.
This completes the capacitor tank construction.
-----------------------------------------------------------------
                THE CAPACITOR ROLL
The capacitor roll is made from the polyethylene sheet and the
aluminum flashing. It is important that all of these materials
are absolutely clean and free from defects.Clean and vacuum up a
work area large enough to lay all of your
plates and dielectric out. If things are dusty you may want to
mop. When the work area is clean; lay down fresh newspaper, or
even better, butcher paper, over the entire work area. You will
need a long, hard, smooth, flat surface to roll your capacitor up
on. A clean, paper covered concrete floor works well, as does a
couple of paper covered buffet or serving tables. 
... Continued in next post

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  Date: 21 Aug 94  19:56:52
  From: Richard Quick                                
    To: Andre Dault                                  
  Subj: Tesla Coil, cap, 2/2
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... Continued from previous post

Cut the poly sheet lengthwise into three equal strips. The
standard material width for this sheet is 48 inches. You will get
three 16" wide strips from the sheet, though only two strips will
be required to make one capacitor roll. The strips must be washed
and wiped on both sides with PrepSol or alcohol and lint free
wipes or high quality paper towels. Then they must be wiped dry.
Static may become a problem here, and the dielectric may collect
dust. A ground strap run to a water pipe may be wired to a copper
or brass brush. The plates and dielectric may be swiped lightly
to ground out static, but do not scratch the material.

Cut two lengths of aluminum flashing 102" long. The flashing must
be six inches shorter than the polyethylene strips. The material
is already two inches narrower. Use a good pair of heavy duty
scissors to cut the aluminum. The strips of flashing (plates)
must have the corners well rounded, and have all sharp edges
smoothed. Trim the corners off with the scissors, then sand all
edges you cut it #150 emery cloth. Drill a hole, 1/2" from one
end of each flashing strip for the terminal mount. Inspect your
plate. It should have no dents, sharp points, "ruffles" along the
edges, etc. Many flaws can be carefully worked out.

The aluminum capacitor plates must be washed and dried. Fill a
five gallon bucket with very hot water and a good squirt of
liquid detergent. Roll the plate up and "dip, swish, and swirl"
until all the sanding grit, manufacturing oil, and dirt wash off.
Rinse the plate well and stand it on its edges on clean newspaper
until it is dried. Don't worry if the plates oxidize a little.

Lay out your meticulously clean plates and dielectric sheets.

Lay one strip of plastic dielectric down first. Then lay a plate
on top and center it. The plate is centered so that there is a
one inch border of dielectric plastic evenly along the long
sides. Line up the end of the plate with the terminal hole flush
(even) with one END of the plastic. The far end of the plate will
be six inches short of flush with the bottom dielectric sheet. 

Lay a second sheet of plastic on top so that it is exactly lined
up the bottom strip of plastic.

Lay the last plate down on the stack and center it. The plate is
centered so that there is a one inch border of dielectric plastic
evenly on both of the long sides. Now, the first plate you laid
will have the terminal end flush with one end of the bottom di-
electric, it makes no difference which end; line up the second
plate so that the terminal end is flush with the end of the
second dielectric sheet, but it must be at the opposite end from
the bottom plate terminal.

Cut two 1" strips of aluminum flashing 14" long. Tape them
together into a 1" strap. Round it and sand it. Then untape it
and wipe or wash the strips. Reassemble and punch a hole in each
end. One hole for a 1/4" or larger screw (tank terminal), the
other for the #8 pan head machine screw (plate terminal). Using a
#8 pan head machine screw, mount this strap into the terminal
hole on the top plate. Use a flat washer, a tiny drop of loctite
thread fastener, and then a nut. Snug the connection down firmly.

This strap serves as a high current lead from the plate to the
terminal mount on the capacitor lid. Make sure that it is the
smooth pan head of the screw pressing into the plastic capacitor
dielectric as the capacitor is rolled up; not the sharp screw
shaft. Do not allow the sharp threaded end to press into the
capacitor. It is a good idea to have a couple of spare patches of
60 or 30 mil plastic to place under the pressure points of the
terminal connector screws. This will help prevent breakdown.

Starting from the terminal end of the top plate on the stack, the
end with the terminal strap already mounted, roll the capacitor
up as tightly as possible. Make sure that the top plate does not
curl around to touch back on itself on the first turn. A strip of
extra plastic here can be helpful. If the first turn of the roll
looks poor, then unroll, line everything up, and try again.

When the capacitor is tightly rolled, do not loosen your grip.
Have an assistant put two wire ties together and slip them over
the roll. When the wire ties are cinched, you may loosen up.

As you rolled the capacitor up, the first plate in the stack
worked its way out of the roll a few inches. This plate should
present you with a terminal hole to mount a second 1x14" strap of
aluminum to complete the second high current lead.

Mount the second lead, making sure the smooth screw head is
against the capacitor, not the sharp threaded end. You will have
one lead coming up from inside the roll, and the other coming up
from the outside. Put at least three wire tie strips around the
roll. Two 12" wire ties connected together will give enough
circumference.

Set the capacitor roll into the tank. Fill with one gallon of
mineral oil. The roll must be covered by at least a quarter inch
of oil to suppress corona and prevent flashover. Note that the
oil soaks into the roll. The level will drop after filling, and
may drop again after use. Check on it occasionally until the
capacitor is fully broken in, a period of about six months.

Connect the leads from the capacitor roll to the tank lid. For
the tank lid terminals use at least 1/4 inch brass machine screws
and tighten down well. The head of the machine screw should be
inside the lid, the first nut on top will hold the connection
tight, the second nut is removable for connection to your
circuit. Do not seal or glue the lid in place.

Do not apply the full rated voltage to these units until they
have set for at least three days, and the oil has had a chance to
soak in to the roll. It is best to start them out at about half
voltage, or less, and run them for short periods for the first
few days on a smaller coil. These units run on the ragged edge of
their voltage ratings, yet they are quite serviceable. On larger
coils it is best to put these units in series/parallel to back
them up against kickback.

Because the material width of the polyethylene is 48", you get
three 16" strips of dielectric from cutting a length. You will
have one strip left over. Because of this, it is perhaps better
to plan on building at least two units at a time. This makes more
efficient use of material, but more so for the use of time. Once
a temporary "clean room" has been established it makes sense to
use it to fullest advantage. 

The effort in building a first class cap is worth the extra time
and expense to do it right. The unit will last longer, withstand
more abuse, and give you more capacitance if it is well con-
structed. Once this effort is expended, and the unit is in
service, don't blow it. Rather than risk the investment you
should build more caps, "backing up" your existing caps and
increasing power by adding caps as you go. 

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  Date: 22 Aug 94  16:52:40
  From: Richard Quick                                
    To: Andre Dault                                  
  Subj: Tesla Coils
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 -=> Sez Andre Dault to All <=-

 AD> Hello there people... All this talk of Tesla coils is right  
 AD> in time.. I'm in the middle of building a Telsa Lightning    
 AD> Generator (tesla coil) But I need some capacitors (big ones) 
 AD> I need .003 - .005 uF from  15,000 - 25,000 WVDC.. If anyone 
 AD> knows a combination of capacitors or how I could build       
 AD> one....  It would be greatly appreciated.

I hope you find the information I posted on construction of high-
voltage pulse discharging capacitors helpful.

Would you mind posting some additional information on your
project? Could you post some specs on the secondary coil
(dimensions, wire size, # of turns etc.). Where did you come up
with the design/plans? Is this to be a spark gap tank circuit? (I
assume yes because of your capacitor specifications).

We would all appreciate hearing more about it, and if you need
specific assistance with any aspect of this project please do not
hesitate to ask, I have more than a few coils under my belt.

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  Date: 08-19-94  23:50
  From: Don Kimberlin                              
    To: Richard Quick                              
  Subj: Tesla Coils
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DK> ...My BIG question:  What records exist describing his
DK> *speaking* on what could be called "radio waves?"  The world
DK> credits Reginald Fessenden with it on December 24, 1906, and
DK> if I can correct that, I'd want to.

RQ>Tesla addressed the Franklin Institute in Philadelphia in
RQ>February 1893, and the lecture was repeated to the National
RQ>Electric Light Association in my hometown, St. Louis, in March
RQ>1893. The two lectures employed all of the equipment and
RQ>elements of Tesla's radio patents.  ....

...Thanks for that point.  We have a FAQ under continuous
revision over in Fido's BROADCAST echo, and I'll sure make
certain we don't understate Tesla's involvement in the
development of what evolved into "radio."

RQ>.... The range limits of a damped wave
RQ>transmitter and the poor quality receiving circuits drove many
RQ>early spark gap xmitters to enormous peak powers ...

...But, as you so often note, not the sort of peaks Tesla worked
to achieve.  I have several really old books here, in which the
people of the spark transmitter era make much of the "decrement"
of their "tuning," essentially the waveshape of their output.  I
note one mention of some form of regulation in which one's
"decrement" was not to exceed a numeric value of 0.2, unless
deliberately detuning in order to create intentional interference
to transmit a distress call.   Since I came along after the spark
era, I never sat down to read with understanding what they were
doing, however it seems they were approaching some of Tesla's
notions.  And, as we both know, what "radio" evolved into
followed a path of sine wave generators in later years, with
pulse generation becoming a byway...

RQ>... Tesla laid it on the line, saying that radio
RQ>(regardless of freq) is highly inefficient when looking at the
RQ>power broadcast vs. the power received. He stated that radio
RQ>is only 10% efficient at best. He compared commercial radio
RQ>transmission efficiencies to commercial electrical power
RQ>transmission (over 90% efficient to the consumer/receiver).

...No doubt about that, due to scattering in most applications,
just to blanket an area with a signal.  The amount of power
received at any one receiver is an infinitesimal portion of that
transmitted...

RQ>What is the efficiency of transmitting alternating currents
RQ>through a wire compared to the efficieny of radiating systems?
RQ>Tesla said that by conduction into the ground and upper
RQ>atmosphere he could deliver not only intelligible signal, but
RQ>useable power. He realized early on the inefficiency of
RQ>radiated signal systems, and focused on a system that employed
RQ>wireless conductors instead. ....

...What "conductors?"  I can see the earth, of course, as one
conductor.  There is a "waveguide theory" particularly applicable
to low frequency radio, where essentially the earth and the
ionosphere form the walls of a "waveguide" around the earth.
Would those be the "conductors" Tesla was alluding to?
 (704)792-9241  (1:379/37.0)
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 Date: 28 Aug 94  23:48:46
  From: Richard Quick                                
    To: Don Kimberlin                                
  Subj: Tesla Coils
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 -=> Sez Don Kimberlin to Richard Quick <=-

 DK> ...Thanks for that point.  We have a FAQ under continuous
 DK> revision over in Fido's BROADCAST echo, and I'll sure make
 DK> certain we don't understate Tesla's involvement in the
 DK> development of what evolved into "radio."

Very kind, and accurate, of you!
 
 RQ>What is the efficiency of transmitting alternating currents
 RQ>through a wire compared to the efficieny of radiating         
 RQ>systems? Tesla said that by conduction into the ground and    
 RQ>upper atmosphere he could deliver not only intelligible       
 RQ>signal, but useable power. He realized early on the           
 RQ>inefficiency of radiated signal systems, and focused on a     
 RQ>system that employed wireless conductors instead. ....

 DK> ...What "conductors?"  I can see the earth, of course, as    
 DK> one conductor.  There is a "waveguide theory" particularly   
 DK> applicable to low frequency radio, where essentially the     
 DK> earth and the ionosphere form the walls of a "waveguide"     
 DK> around the earth. Would those be the "conductors" Tesla was  
 DK> alluding to?

Yes, more or less. Tesla saw the earth as a good conductor when
he tuned to specific earth resonate frequencies below 30,000 Hz.
He stated he could detect natural electrical standing waves in
the ground, and when he tuned his coils to these natural
frequencies, he was able to increase the amplitude of these
standing waves. This is the ground connection of his system.

For the air terminal, Tesla opened an ionized and conductive
channel to the stratosphere. I believe he used a combination of
X-Rays and hard UV produced by his single terminal bulbs which
were mounted on the air terminal of the transmitter station. The 
high-voltage RF current from the air terminal was passed by this
conductive channel directly into the rarified upper atmosphere
where it would conduct freely around the globe.

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  Date: 08-18-94  10:42
  From: Bruce Kingsbury                            
    To: Jonathan Luthje                             
  Subj: What is Tesla?
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JL> if you are referring to a Tesla coil, it is basically
JL> a device which pumps out a whole lot of voltage (via either
JL> a Walton-Cockcroft voltage multiplier, or a transforming
JL> coil in a tower (hence the name Tesla COIL)), and can make
JL> some interesting lightening fX.

You forgot to mention "at high frequency". DC or 60Hz at that
kind of voltage behaves in a much less spectacular manner.

JL> any other questions. . . .just direct them here!

Any other questions would best be directed to Richard Quick, he
seems to be quite an authority on the subject of Tesla coils and
well informed on Tesla's life in general.
 _,,/|
 \o o'
 =_~_= 64-7 847-5513 * (3:774/1150)
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  Date: 08-21-94  16:43
  From: Stan Phillips                              
    To: Andre Dault                                 
  Subj: Building a Capacitor
컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴
AD> I'm in the middle of building a Telsa Lightning Generator 
AD> (tesla coil) But I need some capacitors (big ones) I need 
AD> .003 - .005 uF from 15,000 - 25,000 WVDC.

Television recievers use the Picture tube as the high voltage
filter capacitor. A metal coating on the inside of the glass
(alluminum) and graphite (Aquadag) on the outside.  The actual
capacitance depends on the size of the tube.  While I have never
seen them used just as a high voltage capacitor, there is no
reason why an old picture tube could not be used this way and
they do operate at 20-30 Kv.                   (1:229/15)

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  Date: 29 Aug 94  18:16:17
  From: Richard Quick                                
    To: Bruce Kingsbury                              
  Subj: Tesla?
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JL> if you are referring to a Tesla coil, it is basically
JL> a device which pumps out a whole lot of voltage (via either
JL> a Walton-Cockcroft voltage multiplier, or a transforming
JL> coil in a tower (hence the name Tesla COIL)), and can make
JL> some interesting lightening fX.

BK| You forgot to mention "at high frequency". DC or 60Hz at that
BK| kind of voltage behaves in a much less spectacular manner.

JL> any other questions. . . .just direct them here!

BK| Any other questions would best be directed to Richard Quick,
BK| he seems to be quite an authority on the subject of Tesla 
BK| coils and well informed on Tesla's life in general.

Thanks for the complement and the vote of confidence Bruce!