Hi DC,Streamer capacitance is not part of the top load object geometry. I tried to do this in the past (in various ways), but was unable to match a streamer load with the existing top load objects available. When it comes to streamer loading, this is where "tuning" a coil is in the hands of the experimenter. I run high on primary inductance myself. I suspect most do. Javatc will give you the tuning as based on everything except the streamers. For some coils, the effect is small and negligible. For moderately higher powered coils, the effect can be significant. Transformer power has everything to do with this.
There was a time (a year or two ago) that I realized Javatc was one step away from tuning the coil based on the predicted streamer lengths. But what hindered my ability to add this was the fact that Javatc's core LC engine is Geotc of which I do not have control of nor do I have the programming skills to build upon it. All top load objects are dimensioned center to the coil. What really needs to happen to incorporate this is to have the ability to insert a top load object (rod representing a streamer arc) that issues from edge of toroid out to some length as proposed by the system max power or whatever. I can make all that happen, but the the Geotc portion I can't.
I tried using the existing objects to accomplish this but I was never satisfied with the results. For example, half a streamer on both sides of a toroid is "not' linear to a single streamer on one side. Once I realized this, I knew I needed Paul Nicholson. I wrote an email to Paul for the implementation of this into Geotc, but at the time he wasn't getting my emails (lost in cyberspace I think). Paul also hates JavaScript more than I do (no, I don't think so!), so likely this can't be done unless I can figure a method to use existing objects. I have only at my disposal toroids, spheres, cylinders, and discs. All of these I can configure into a "rod" shape, however, they all implement out on both sides from the center of the coil and that is my problem. I couldn't find my happy spot and eventually got busy with other things never to resolve this situation. I still long to do it.
For now, tuning is a close ballpark (and closer for lower powered coils than larger powered coils which have longer spark lengths). But even this is not linear. Coil geometry is part of how much the streamers will affect tuning. Some very little, others more.
Thanks for asking this question DC! There are actually many of these type of issues very few even think about which I've already considered and tried. In the end, I have to ensure Javatc performs as needed, and in areas that I just can't control, I'm hindered to implement. I don't like to rely on theory for Javatc. For example, SecQ and Sec Rac. It's not theoretical output but a large number of various coil configurations (real coils) and top of the line measurements which enabled this output to become active. If it wasn't for the large number of empirical data which Malcolm Watts provided me, I would not have included it. But since Malcolm did give excellent top of the line measurement data, and because I was also able to include other coilers various measurements into the mix, the data was really excellent. I did have to perform some factors into the low hd coils (1:1, 1.5:1, etc.) to follow the curve, but this was needed. Q basic calculation was based on Fraga, Padros, and Chen "Practical Method and Calculation of AC Resistance of Long Solenoids", IEEE Transactions on Magnetics, Vol. 34, No. 1, January, 1998, pp. 205-212. They did not include low h/d coils. So, curve fitting was needed for those small h/d's. In the end, the measurement comparison to Javatc is graphed here:
http://www.classictesla.com/temp/RAC-Q2.gifIn the area of Q, Javatc did very well considering these were "measured" comparisons. Thus, I decided to include it into Javatc following evaluation. It certainly got you in the ballpark of Q, and even the low h/d areas did well. Thus, I was able to provide a somewhat decent prediction of Q for a decent range of coil h/d's. This has never been done before in any program, so it was a good enhancement for Javatc and the TCML. Not sure they all realize the work involved, but it's available now regardless.
I hope someday we can include spark loading. I'll keep working on it. Take care, Bart DC Cox wrote:
Which brings to mind a question. Bart --- do you account for streamer length in JAVATC, ie, do you add some topload capacitance to give the best pri configuration based on added streamer capacitance, or does it just do distributed capacitance and topload capacitance in the calc? Dr. Resonance On Tue, May 27, 2008 at 12:11 PM, b alex pettit jr <a_pettit_jr@xxxxxxxxx> wrote:Continuing with this project .... I just ran several tests measuring the F_res of this 4.5" dia x 21" 940 turn coil. I drove the primary ( without cap) via sig.gen and measured the coil's response on a freq.counter and scope. It was quite evident the coils F_ res was 268.98 KHz. Half Power points at 268.3 KHz and 269.5 KHz = a Q of 224 and well correlated to JAVATC's Q calc of 285. (The Primary and lower end of the Secondary were tied to my in-ground copper stakes) With slight tweaks in ground plane and adding a turn or two to the Sec parameters, JAVATC calculated a F_res = 268.86 KHz ( as close as I felt needed to match 268.98 KHz). The Rest of The Story: That F_res via JAVATC tunes the Primary at 6.797 turns, a HalfPower point at 6.777. With a 45" circumference of the Primary at turn 7, this equates to +- 3/4" from resonance to half power point frequencies. BUT, I added a 'StreamerLoad " wire of 36" , it detuned the F_res by 30 ( thirty ) Hz ! This changes the Primary tuning point to 7.751 turns ...a full turn ! How does one actually Tune a Tesla Coil ? I am considering a banjo type coil element equal to 1/3rd turn of the main primary to use for experimentation. Or, how precise IS the tuning of Pri to Sec ? I know that in lightly damped mechanical structures, the frequency of the excitation is extremely critical for full excitation. This is becoming a tail chasing dog senario... am sure also changes in coupling factor detune the system ... good news, multigap spark gap is working and streamers are exceeding 24 inches... Thanks, Alex P ******************************************************************** J A V A T C version 11.8 - CONSOLIDATED OUTPUT Tuesday, May 27, 2008 2:32:20 PM Units = Inches Ambient Temp = 68°F ---------------------------------------------------- Surrounding Inputs: ---------------------------------------------------- 38 = Ground Plane Radius 100 = Wall Radius 100 = Ceiling Height ---------------------------------------------------- Secondary Coil Inputs: ---------------------------------------------------- Current Profile = G.PROFILE_LOADED 2.26 = Radius 1 2.26 = Radius 2 2.3 = Height 1 23.3 = Height 2 943 = Turns 24 = Wire Awg ---------------------------------------------------- Primary Coil Inputs: ---------------------------------------------------- 4.25 = Radius 1 7.647 = Radius 2 3.3 = Height 1 3.3 = Height 2 6.793 = Turns 0.25 = Wire Diameter 0.0187 = Primary Cap (uF) 0 = Total Lead Length 0 = Lead Diameter ---------------------------------------------------- Top Load Inputs: ---------------------------------------------------- Toroid #1: minor=3, major=12, height=30, topload ---------------------------------------------------- Secondary Outputs: ---------------------------------------------------- 268.86 kHz = Secondary Resonant Frequency 90 deg° = Angle of Secondary 21 inch = Length of Winding 44.9 inch = Turns Per Unit 0.00217 inch = Space Between Turns (edge to edge) 1115.9 ft = Length of Wire 4.65:1 = H/D Aspect Ratio 28.4093 Ohms = DC Resistance 30794 Ohms = Reactance at Resonance 1.36 lbs = Weight of Wire 18.229 mH = Les-Effective Series Inductance 20.096 mH = Lee-Equivalent Energy Inductance 19.905 mH = Ldc-Low Frequency Inductance 19.223 pF = Ces-Effective Shunt Capacitance 17.437 pF = Cee-Equivalent Energy Capacitance 32.248 pF = Cdc-Low Frequency Capacitance 5.61 mils = Skin Depth 11.652 pF = Topload Effective Capacitance 108.1284 Ohms = Effective AC Resistance 285 = Q _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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