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TESLA COIL DESIGNS...

 * Original msg to: Cwolins-at-orion.it.luc.edu
 * Carbons sent to: usa-tesla-at-usa-dot-net
                    usa-tesla-at-usa-dot-net

Quoting Mattthew <cwolins-at-orion.it.luc.edu>:

> Hello Richard,

> This is Matthew Klueppel Again. You sent me close to a hundred
> pages about the construction of Tesla coils.  I have read all 
> of this information and found it to be extremely useful.  I 
> appreciate your quick response to my needs. After evaluating 
> the information I based my first medium powered coil using the
> following coil parameters,processes, and hardware.

> Equiptment:     15kV 60mA Neon Transformer 
> Multi-Port Spark Gap 
> Air Compressor (for air blasts to spark gap if necc.)

You won't need an air compressor unless you want to build a set
of air-blast gaps. For starters you can get by with two of the
cylinder static gaps. These plans are located in the 
nic.funet.ni  FTP site in the file SPARGAP.ZIP 

> Homemade Capacitor:     15,000KV * 1.414 * 2 = 42,400 Minimum
> Peak-to=Peak Voltage 4 layers of 6 mil poly , Aluminum Roof
> Flashing 1kV * 6 * 4 = 24kv per cap. 
> 3 capacitors in series = 24KV * 3 = 72KV protection 
> A little overkill is always good for caps. I will series and 
> parallel combo these to get the required capacitance. The cap 
> will be filled with mineral oil and vacuumed twice to remove 
> air (NEED HELP CALCULATING MAX CAPACITANCE FOR THIS XFMR)

This transformer will match pretty well with a .01 microFarad
capacitor.

> Primary Coil of 1/4" Thin Wall Copper Tubing, 15 - 18 Turns on
> a 30 degree conical form w/ 1/4" spacing between turns. First 
> turn starts 1/2" beyond the outside secondary coil form.

I would allow 1-1/2 inches of space beteen the two coils at the
closest point.

> Secondary Coil  6 7/8" O.D. by 24" Length Plastic Tubing 
> It's not pvc. I got this tubing from a military surplus.  Its 
> 3/16" wall thickness is a very soft plastic I am not sure what
> type of plastic this is. But I am going to give it a shot.
> About 900 turns of #22 AWG Magnetic Enabled Wire        

This sounds fine. I would make a wild guess and say you may have
a polyethylene tube. You should test a tiny portion of the
proposed coil form and make sure you can find some adhesive to
hold the end caps on and mount the RF ground plate. You may be
able to heat weld this plastic, but it is very tricky...

> Terminal Capacitance    Toroid, Aluminum Soldered Stove Pipe 
> Tubing or a metal tubing connected at both ends with inner sup
> port

No problems here.

> Spark Gap, Not really sure how many points to use with a
> spark gap (Hoping for some Help HERE!!!)

First off, you don't want any points. You want smooth surfaces
that are either flat or curved. The actual number of gaps used
depends on the voltage and the distance between electrodes. You
should find that 8 - 10, .030 inch gaps in series, will work very
well. Get that file SPARKGAP.ZIP from the  nic.funet.fi  site.

> Question and Comments: Please comment on these.

> 1. About neon sign transformer effiecency. You said "Power 
> Factor Correction (PFC) across the line " Where are these 
> capacitors placed in the circuit.

These capacitors are placed across the line on the primary side
of the neon transformer.

> Are they used on all neons. 

Some neons are already power factor corrected by the factory. The
PFC capacitor is imbedded in the potting on these transformers.

> My xfmr draws 8.25A -at- 120V This is 990VA with an output of 
> 900VA.  About 90VA are lost due to heat and or flux.  

This transformer is already power factor corrected.

> What are "SHUNTING PLATES" used for?    

These are an integral part of the built in current limiting used
in the core of neon sign transformers. The shunting plates
literally shunt magnetic energy away from the secondary high-
voltage windings. This shunting effect limits the output of the
transformer.

> So...  Do I need to do anything to my transformer to use 
> it effectively or can I run as is.  

This transformer can be used as is with the appropriate circuit
protection components (bypass, safety gap, RF choke).

> RF & High Voltage Spike & KickBack Protection Circuit. I have a
> shemactic which I obtained from the tesla group ftp.

    X1                                           

   ||O--------------------------------nnnnnnnn--TO-TANK-CIRCUIT->
   ||O            |             |        RF1
   ||O         ------- BC1      |                                
--O||O         -------          |
  O||O            |             *
  O||O--GRND------|-----GRND----* SG                             
  O||O            |             * 
--O||O         -------          |
   ||O         ------- BC2      |                              
   ||O            |             |        RF2                 
   ||O--------------------------------uuuuuuuu--TO-TANK-CIRCUIT->

Where:

        X1 = Is the step up xfmr with grounded center tap
      GRND = Dedicated RF Ground 
       BC1 = Bypass Capacitance
       BC2 = Bypass Capacitance
        SG = Safety Gap w/grounded center post
       RF1 = Radio Frequency Choke
       RF2 = Radio Frequency Choke

> Does this look OK?  Can you comment on these values?

Generally I don't like using more than .001 MFD (maximum) of
bypass capacitance between any HV buss and ground, or directly
across the HV buss. This is one instance where a little less
capacitance is really a lot better than a little more. 

The RF chokes need to have a value around 4 - 6 miliHenries.

> Can you please explain where ALL of the grounds throughout the 
> system are connected and interconnected etc.  Ex.  WHich 
> grounds are connected and which are separated.

I recommend using to separate and distinct grounds when working
with Tesla systems. The 60 cycle ground is code for most
locations. Use this to ground your power cabinet, variac housing,
RF filter housing, relays, control xfmr cores, etc.. From your
power controls/cabinet you bring hot wires only to the primary of
the step-up transformer. Now 120V coilers will bring a neutral
wire out to the primary on the step-up, but it will be isolated.

The core of the step-up xfmr, safety gaps, base of the secondary
coil, objects such as strike shields, gap fan and motor housings,
etc., are all grounded to the dedicated RF ground.

> RF Ground I have a large ground source which can be connected 
> about 20 Feet Away. I will used some type of heavy copper
> bar.  

Wide flat strap will make better use of the conductor. Use a VOM
to make sure there is no direct connection between your RF ground
and the 60 cycle ground.

> After Hooking up all of these componets for safety ETC... I 
> assume these extra components will affect the tank freq. Please
> comment on any correction factors which will needed to be 
> taken.

Any effects will be neglible if you place your RF kickback and
filter components back away from the tank circuit. Tune for best
spark.

You asked for a wiring diagram that showed the RF grounding
points: look at the diagram above. The GRND is all RF ground. The
base of the secondary coil is also grounded to this point. 

Richard Quick


... If all else fails... Throw another megavolt across it!
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