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circuits.txt



CIRCUIT TEXT to go with CIRCUIT.GIF

Most people who run coils begin with 120 volts -at- 60 cycles. 
If this is the case with your anticipated power feed, then one of
your two feed lines will be a neutral wire (zero voltage), and a
slight circuit modification will be required. THIS CIRCUIT
SCHEMATIC IMPLIES 240 VOLT OPERATION THROUGHOUT, WHERE BOTH 60
CYCLE FEED LINES ARE HOT, AND, A HIGH VOLTAGE STEP UP TRANSFORMER
THAT DOES NOT HAVE A GROUNDED CENTER TAP. Those who start out
using 120 volt line feeds usually end up switching over to 240
volt operation in a hurry: the amperage requirements of Tesla
Coil power supplies makes 240 volt operation very desirable.  

However this ZIP package includes the specific instructions
required for safe, RF supressed operation when using 120 volt
feed lines, and/or, neon sign (grounded center tap) step up
transformers. Alternate wiring diagrams for these, and other,
modifications are provided in the following suppliments:
CHOKE.GIF & CHOKE.TXT, CHOKE1.GIF & CHOKE1.TXT, CHOKE1A.GIF &
CHOKE1A.TXT. When and where these alternate wiring diagrams are 
employed they will be referenced.    
---------------------------------------------------------------

Starting with the upper left hand corner of CIRCUIT.GIF, the 60
cycle line feed provides power to the circuit. These line feeds
are labled 60 Hz in the CIRCUIT.GIF schematic.
 
CP1 refers to Circuit Protection devices. This is a fuse, circuit
breaker, or fusable link. The current rating of the Circuit
Protection device is dependant upon the current rating of the
step up transformer (X1). I allow a 150 - 200% margin over the
transformer input current rating when using the plate value of
unmodified neon sign transformer(s) {transformer = xfmr or
xfrmr}. The text files in this packet contain precise
instructions for modifing neon sign xfmrs for high efficiency
Tesla power supplies. When using modified neons or other types of
step up xfmrs, then I allow a 35 - 50% margin over the plate
rated input current of X1.

SW1 refers to the power control switch(s). In the old days a
knife blade switch was common, but I prefer a remotely operated
power relay/contactor. When the sparks are flying I am hesitant
to grab hold of live switch: I like a remote operated relay with
a step down transformer and a low voltage switch. The choice is
yours...

Line Filter: These are pretty much self explanatory; except that
I run them in reverse. We are trying to prevent the RF generated 
from the apparatus from entering into the house wiring, not the
other way around, which is how these filters are designed. These
filters are generally marked on the case, just put the "LINE"
side facing towards the coil, the "LOAD" side faces the 60 cycle
breaker box. NOTE: alternate filter schematics are given and
described/debated in CHOKE.GIF and CHOKE.TXT in this packet.

VX1  This is a Variable Xfrmr, Variable Transformer, Powerstat,
Variac, Autotransformer, Autoxfrmr, etc.... Some type of
variable transformer used to control the input voltage to X1. The
current rating on the variable transformer should be matched to
the value of the Circuit Protection device.

Line Filter: see above.

X1  High voltage step up transformer. Typical types include Neon
Sign Xfrmrs, Potential Xfrmrs, Plate Xfrmrs, Pole Pigs (pole type
power distribution type xfrmrs). This is where circuit modifica-
tions may have to be made to the general diagram in CIRCUIT.GIF.
If you plan on using a neon sign xfrmr for X1, then plan on
modifing BC1 according to the layout given in CHOKE1A.GIF and
CHOKE1A.TXT. Precise values and layouts to protect neons and the
60 cycle line supply are given in these documents. Plate type,
pole type, or potential type xfmrs are protected according to the
layout given in CIRCUIT.GIF and CHOKE1.GIF, CHOKE1.TXT.

BC1 is the protective Bypass Capacitor. See the CHOKE documents
refered to in the above paragraph depending on transformer type.

RFC1, RFC2 are Radio Frequency Chokes: Values and construction
details are given in CHOKE.TXT, CHOKE1.TXT and CHOKE1A.TXT.

G1 is the main system spark gap. Please refer to AIRBLST.GIF &
AIRBLST.TXT or CYLNDR.GIF & CYLNDR.TXT for detailed construction
specifications and diagrams of these components.

C1 is the High voltage, plastic film, pulse rated, Tesla
capacitor. Refer to CAP.TXT for construction details of this
component. The general text files from OCT-93.TXT or NOV??-93.TXT
contain additional detailed information on these capacitors. See
TESLA.TXT for commercial sources of Tesla Capacitance.

L1 is the Tesla Tank primary coil. Construction details and
theory are extensively covered in the general text files (see the
OCT-93.TXT or NOV??-93.TXT)

L2 is the Tesla Secondary Coil. Construction details and theory
are covered extensively in the general text files. Specific
construction details for 200 KHz and 450 KHz coils are given in
the general texts included in this packet.

T1 is the discharge Terminal. Spheres have been traditonally
recommended, but TOROID discharge terminals give the last word in
Tesla coil performance. Again... The general text files give
complete descriptions and construction guides.

It should be noted that the RF GRND (Radio Frequency Ground) is a
dedicated Tesla ground: The core of X1 and all grounded compon-
ents on the coil side of X1; are grounded to a heavy, dedicated,
Rf grounding system. The general text files cover RF grounding
extensively. 

Other coil notes: In the event that X1 is not internally current
regulated (neons are internally regulated, the other types are
not) then some type of current limiting should be added (in
series) to the primary of X1 to prevent "brownouts" and
"blackouts" when you throw the switch. Pole types transformers in
particular are dangerous without some type of current limiting.
Details are given in the general text files included in this
packet.

Tesla Tank configurations (C1 - L1 - G1) are varied, and need not
conform with the layout given in CIRCUIT.GIF; see the layouts in
TANK.GIF, TANK1.GIF, & TANK2.GIF for the common variations. There
are no related text files for these GIFs, the variations being
pretty much self explanatory. The layout given in CIRCUIT.GIF
tends to be less brutal on X1 during operation.

END CIRCUIT TEXT_
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CHOKE.TXT TO GO WITH CHOKE.GIF

This is a radio frequency (RF) and high voltage spike and
kickback protection circuit. It protects your power control
cabinet, and the low voltage 60 cycle house wiring. This circuit
is recommended for the low voltage side of all types of step up
transformers, regardless of taps, grounds, etc. on the windings.

X1 is the step up transformer. The center core is grounded to the
dedicated RF ground that also grounds the safety gap and the
base wire of the Tesla secondary.

RFC 1A and RFC 1B are about 5-10 turns of heavy insulated wire
(sufficient to carry the current requirments of X1) on a large
iron powder or wire ring toroid core. I use 4-6 diameter iron
powder toroids and heavy cable to wind these chokes.

"Protective Capacitors PC1 and PC2 are not critical and can be
rated in the vicinity of .5 to 2 microfarads. Use a voltage
rating as high as possible. The usual 400-600 volt capacitors
will not withstand kickbacks for very long. 1 KV rating or more 
should work fine."

In place of this circuit, a large heavy duty commercial EMI/RFI 
line filter may be placed here. These filters offer the
convienience of good efficiency in a compact unit. Where current
throughputs are high I use several in parallel. Quality
commercial line filters employ iron powder chokes, as well as the
"PC" capacitors of the circuit at the top of this post. The Line
Filters I use also have RF choke coils in the ground path; the
ground wire can be run reversed (it is neutral) and can be used
to trap stray RF, preventing ground path contamination to the 60
cycle breaker box. I use a minimum of two independent grounds.

컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴
  Date: 08-08-94  15:25
  From: Terry Smith                                
    To: Richard Quick                              
  Subj: Tesla Coils
컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴
       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. 


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)

컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴
  Date: 11 Aug 94  17:01:49
  From: Richard Quick                                
    To: Terry Smith                                  
  Subj: Tesla Coils
컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴
       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 of 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.
 
END CHOKE TEXT_
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CHOKE1.TXT TO GO WITH CHOKE1.GIF

This is a radio frequency (RF) and high voltage spike and
kickback protection circuit. It protects your power supply (high
voltage step up xfrmr) and low voltage house wiring.

X1 is the step up transformer. The center CORE is grounded to the
dedicated RF ground that also grounds SG1 (safety gap) and the
base wire of the Tesla secondary.

BC1 is a Bypass Capacitor. I use high voltage barium titanate
doorknobs, with stacks of four or more in series. A typical
rating for a single cap would be .003 microfarad -at- 30 KVDC, and
using four of these caps in series I get .0007 microfarads at 120
KVDC. Since the AC rating is about half the DC rating on these
type capacitors, figure a series stack of four will withstand a
kickback of 50-60 KVAC in this use.

RFC 1A and RFC 1B are about 15-20 turns (minimum) of insulated
wire on a large iron powder core. I use 2" diameter iron powder
toroids to wind these chokes.

This circuit is not recommened for neon sign transformers unless
the value of BC1 is divided in two, and the center of the
capacitor stack is grounded with the xfrmr core. (SEE CHOKE1A)


  ------
  |      |      X1                    RFC 1A
컴|컴컴컴|컴컴커붚컴컴컴쩡컴컴컴컫컴컴程程粘컴> TO TESLA TANK
  |      |     )(              
  |      |     )(              
  |      |     )( BC1 컨       O
  | LF1  쳐.  )(     컫       o컴. SAFETY GAP
  |      |     )(              O
  |      |     )(              
  |      |     )(              
컴|컴컴컴|컴컴켸봉컴컴컴좔컴컴컴컨컴컴훃UUUU컴> TO TESLA TANK
  |      |                            RFC 1B
  ------     賈
               grnd

LF1 is a commercial heavy duty line filter wired in reverse.
Where current throughputs are high I use several in parallel.
Quality commercial line filters employ iron powder chokes, as
well as the "PC" capacitors of the circuit at the top of this
post. The Line Filters I use also have RF choke coils in the
ground path; the ground wire can be run reversed (it is neutral)
and can be used to trap stray RF, preventing ground path
contamination to the 60 cycle breaker box. I should note that I
use a minimum of two independent grounds. The core of X1, and
everything to the right of X1 in this diagram, is grounded
separately to a heavy, dedicated, RF ground. This heavy RF ground
is also used to ground the base of the Tesla secondary.

Note that the core of X1 is grounded. 

BC1 is a Bypass Capacitor. I use high voltage barium titanate
doorknobs, with stacks of four or more in series. A typical
rating for a single cap would be .003 microfarad -at- 30 KVDC, and
using four of these caps in series I get .0007 microfarads at 120
KVDC. Since the AC rating is about half the DC rating on these
type capacitors, figure a series stack of four will withstand a
kickback of 50-60 KVAC in this use.

Where center tap ground type xfrmrs are used for X1 (such as neon
sign cores) BC1 must be divided into two units, and the center of
the stack must be grounded with the xfrmr core (see the arrange-
ment of PC1 and PC2 in the top most diagram). Use no more than
.001 or so microfarads per side, as too large a bypass capaci-
tance will create an oscillating current in the high voltage
windings on your step up xfrmr that will cause the xfrmr to fail.

RFC 1A and RFC 1B are about 15-20 turns (minimum) of insulated
wire on a large iron powder core. I use 2" diameter iron powder
toroids to wind these chokes.

END CHOKE1.TXT_
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CHOKE1A.TXT TO GO WITH CHOKE1A.GIF

This is a radio frequency (RF) and high voltage spike and
kickback protection circuit. It protects the step up transformer 
(X1) where the high voltage winding has a grounded center tap
(like the typical neon sign transformer). It also protects the 
low voltage supply side of the circuit (house wiring).

X1 is the step up transformer. The core and center tap are
both grounded to the dedicated RF ground that also grounds SG1
(safety gap) and the base wire of the Tesla secondary (L2).

BC1 and BC2 are Bypass Capacitors. I use high voltage, barium
titanate, doorknobs; using typically a stack of three or more in
series. A typical rating for a single capacitor of this type 
would be .003 microfarad -at- 30 KVDC; and using three of these caps
in series I get .001 microfarads at 90 KVDC. Since the AC rating
is about half the DC rating on these type capacitors, figure a
series stack of three will withstand a kickback of 45-50 KVAC
from the Tesla Tank in this use. Since the centers of these
stacks are grounded there is extra (two times) safety margin.

Note that the values of BC1 & BC2 must be kept below .001 micro-
farads in each stack, and that the center of the stack must be
grounded. Failure to observe these specifications will allow
parasitic oscillations to set up in the high voltage windings of
the step up transformer. These parasitic oscillations are high in
current, and will cause the step up transformer to fail.

RFC 1A and RFC 1B are about 15-20 turns (minimum) of insulated
wire on a large iron powder core. I use heavy 2" diameter iron
powder toroids to wind these chokes.

This circuit is recommened for neon sign transformers, or any
type transformer, where the center taps of the step up windings 
are grounded to the core. The Bypass Capacitance is divided in
two, and the center of the capacitor stack is grounded with the
xfrmr core. (SEE: CHOKE1 for other type xfmrs)

END CHOKE1A.TXT_
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