Tesla simulations vs. scope traces (fwd)
---------- Forwarded message ----------
Date: Sat, 20 Dec 1997 19:27:47 EST
From: Rscopper <Rscopper-at-aol-dot-com>
Subject: Tesla simulations vs. scope traces
I've been working with some PSPICE simulations again, and a few interesting
things have surfaced.
1) With a digital scope (500mhz) I captured some traces of my 8X6 coil
operating and ran the output through a FFT program at work. The scope was
triggering on a 4MHz ring-up , followed by a 100KHz sine wave.
2) WinTesla calculations predicted 91.1KHz secondary frequency.
3) A simple RLC PSPICE simulation AC analysis predicted 91.458KHz.
4) A distributed ladder network of series inductors simulating the bottom of
the coil equal to the total secondary inductance/2 then /4 ,/8, etc..with
capacitances to ground starting at the top equal to total secondary self-
C/2+Toroid-C then self-C/4,/8, etc...showed a 91.58KHz component for the
Inductor L7 at the top of the coil, and also 1,2,3,and 4MHz spikes for the
Inductor L1 at the bottom of the coil...simillar to the scope traces from the
5) A resistor between the top C of the secondary and the toroid-C (100ohm)
resulted in the removal of the higher frequency components in the AC analysis.
6) Both the scope traces and the PSPICE simulations showed the high frequency
components are of at least 3 to 1 greater magnitude than the approx 100KHz
component. I think this may be the secret of the magnifier. If you tuned the
extra coil such that it's res freq is equal to the L1 ring-up, you could get 3
times the output?????
I am building an extra coil for res at 4MHz to test this (without any coating
so I can add or remove windings for tuning.)
I can't do any more tests until I rebuild my RSG (The cold weather caused some
negative thermal expansion, and hence, a gap crash)
The high frequency component of the spectrum is based somewhat on how the
resistance is distributed along the other components, since my simulations and
the scope traces don't match as of yet, the correct distribution I have yet to
I will post images of the scope traces, PSPICE circuit, and PROBE output on my
web page http://members.aol-dot-com/rscopper/index.htm as I get them formatted.
R. Scott Coppersmith