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Re: DRSSTC Tuning Paper (Rough Draft)

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Dan,

I ran numbers with Javatc on your data (thanks for sending). By referencing your data here and your write up, aspects were easy enough to retrieve. I went through and ran the uncoupled pri and sec numbers then the coupled numbers.

Pri (uncoupled):
Dan       159.9 kHz   9.2uH   5.5 turns
Javatc    159.6 kHz   9.2uH   5.5 turns

Sec (uncoupled):
Dan 288 kHz 39mH (the measurement seems high. Maybe someone else can verify?).
Javatc    330 kHz   37.6mH

Sec + toroid (uncoupled):
Dan       198 kHz
Javatc    200 kHz

Pri, Sec, + toroid (coupled):
Dan       not indicated (only upper and lower resonant modes)
Javatc    198 kHz

I don't see anything wrong here. If the coil was autotuned (and adjusted to keep top of primary even with bottom secondary turn) Javatc would end up at 4.2 turns (and Javatc would be right). Dan has shown in his paper that his coil favors a detuning high on inductance of about 19% (Dan showed as operating nearer the lower resonant mode). I have detuned coils high on inductance up to 13% on occasion for best operation and they were sparkgap coils. Typically, 5 to 8 % seems to be the norm there.

What Dan has found through his measurements is that arc loading detunes the system. By detuning the primary, the "loaded" system will pull towards resonance as the arc length is reached (versus falling away from resonance which is what can happen if the system is tuned without spark loading in mind). This is not new, but there may be more loading for a given arc length on a DRSSTC vs a sparkgap coil? I guess that is what I'll be looking out for on these systems. Neat stuff!

Take care,

Tesla list wrote:
Original poster: "Mccauley, Daniel H" <mailto:daniel.h.mccauley@xxxxxxxx><daniel.h.mccauley@xxxxxxxx>

Here are the coil specifications:

Toroid:  13" x 4"
Secondary:  4.5" x 12" winding length
Secondary Wire:  30 AWG
Primary Coil:  Approx. 5.75 to 6.00 turns of 0.25" tubing (0.20 spacing)
Primary Capacitor:  0.108uF

Secondary Coil 1st turn is approximately equal to the top turn of
primary coil.  Spacing between toroid and top turn of secondary is about
2 inches.

Hope this helps.


thanks for the information. JAVATC uses raw geometry to calculate the
resonant frequency, coupling factor, recommended tuning point etc. So
it would be easier if I had some of the coil specs. However, I can
input some guesses until the electrical parameters match what you have

I assume the Cprimary is 0.108uF.

----- Original Message -----
From: <mailto:tesla@xxxxxxxxxx>Tesla list
To: <mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx
Sent: Thursday, June 29, 2006 3:52 PM
Subject: RE: DRSSTC Tuning Paper (Rough Draft)

Original poster: "Mccauley, Daniel H"


The actual tuning point is shown in the paper.  This equates to 9.2uH of
primary  inductance.

Lsec= 39mH
Coupling = .14 (for 9.2uH tuning point)
Cpri = 0.108uH
Csec(total) = 17.5pF
Rsec = 150