TSSP and JHCTES

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "John H. Couture by way of Terry Fritz <teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>


All -

The basic classical Tesla coil parameter is the resonant frequency (Fres).
This frequency is easily determined using graphs or computer programs. The
simplest problem is finding the Fres of the secondary coil without a
secondary terminal (topload). The TSSP Virtual Secondary Database includes a
graph of this type. The graph is for the resonant frequency vs the h/d of
the secondary coil. The graph includes a series of curves for different wire
sizes and "sr" values.

The graph gives the coiler the basic resonant frequency for his secondary
coil without a secondary terminal. This will be the basic resonant frequency
including both the primary and secondary circuits of any Tesla coil the
coiler designs that is using this particular secondary coil.

The information shown on this graph can also be easily found with the JHCTES
Ver 3.3 computer program. The basic equation is

      Fres = 1/(6.283 sqrt(LsCs))
Fres  = Basic resonant frequency
Ls    = Sec coil inductance - from Wheeler equation
Cself = Sec coil self capacity - from Medhurst equation

The 3 secondary coil JHCTES inputs are
     Secondary Radius
     Secondary turns
     Secondary turns per inch

The above will give the coiler the basic resonant frequency of the secondary
coil without a secondary terminal and with no surrounding effects that would
affect the frequency. When a secondary terminal is added the basic Fres
changes by an amount that can be estimated using Terry's E-Tesla program.
Terry's program determines the new Fres using the new secondary terminal and
also the effects of the surroundings. This new Fres can then be used to find
the effective secondary terminal capacitance using the JHCTES program. the
JHCTES sec term is adjusted until the Fres appears in the outputs.

The above procedure will give the coiler a close approximation to the true
Fres for his new TC. To find a more accurate Fres the coiler should use
Bart's JAVATC program. After the TC is built and the coil properly tested
for the Fres the JAVATC program and the test frequencies should be the same.
This procedure will give the coiler a better check for his TC parameters
than has ever been available in the past.

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Example for the TSSP graph -
Given - Sec coil winding length = 80 cm = 31.5"
         Sec coil h/d = 4     # 24 AWG (.0201")
         sr = .0201/.02273 = .884
         1/44 TPI = .02273
The TSSP graph shows the Fres = about 150 Khz

Example for the JHCTES -
Inputs - Secondary only - Ignore other inputs -
     Sec coil rad      = 3.937" (10 cm) - (31.5/4/2)
     Sec turns         = 1386 (31.5 x 44)
     Turns per Ins     = 44 - (.884/.0201)
     Sec hgt above Pri = 0
     Sec Term pf       = 0

Outputs - Fres = 149.5 Khz   Sec Ind (Ls) = 85.15 mh
           Sec Cself = 13.31 pf  h/d = 4.00

We now have 5 checks for the resonant frequency of a Tesla coil without a
topload (secondary terminal) and 3 with a topload.

    1. TSSP Graph
    2. JHCTES program
    3. E-Tesla program
    4. JAVATC program
    5. Test

Notice that the Fres of the secondary coil without the secondary terminal
should be the same for all of the 5 check methods. If one of the methods
differs from the other 4 (that are equal) that one method is incorrect.

The JHCTES Ver 3.3 TC computer program can be found at

    http:\\www.mgte-dot-com

Click on Tesla, then JHCTES, then at bottom of Book page.
This is an on-line program. Don't forget to click "Calculate" after you make
changes.

John Couture

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