From: "Terrell W. Fritz"
Date: Sat, 21 Oct 2000 21:40:29 -0600
Subject: [TSSP] NSVPI - Latter Results
Hi All, All the data is in, and my new probe seems to be totally successful!!! Some details... I found that the windings on my space wound coil are imperfect a bit. Some sections had more or less turns than others. The windings loosened during a dry spell once and the winder is not perfect. This caused a little jumping in the numbers. I was worried that it was the probe but the numbers repeat extremely well so I blame the windings not being the exact same number in every section. As seen in the photos, the coil is on a rather quickly made ground plane. It is split so as to avoid the shorted turn effect. I measured the Q of my coil using the Q=Fo/BW formula and based that on the measured RMS input current. The Q was 59.25 (146.34 / (147.61-145.14)). With an input voltage of 0.6606 RMS, I would expect the top voltage to be: 0.6606 x 1.414 x 59.25 = 55.35 volts. The sum I measured is 69.72 volts. Now for the exciting data! The profile is pictured at: http://63.225.104.49/TeslaCoils/Misc/PaulNich/ProfilerPics/TheProfile.gif The excel file is at: http://63.225.104.49/TeslaCoils/Misc/PaulNich/ProfilerPics/Profiler.xls The same data in text format is at: http://63.225.104.49/TeslaCoils/Misc/PaulNich/ProfilerPics/ProfileData.txt The picture of the profile in the first link says it all... An exact match of what Paul's program predicts!! Here is the tabular data: Section Voltage Voltage+Vdiode Summation (peak) 1 1.48 1.6 1.6 2 2 2.12 3.72 3 2.38 2.5 6.22 4 2.54 2.66 8.88 5 2.76 2.88 11.76 6 2.7 2.82 14.58 7 3 3.12 17.7 8 2.8 2.92 20.62 9 3.02 3.14 23.76 10 2.92 3.04 26.8 11 2.88 3 29.8 12 2.84 2.96 32.76 13 2.8 2.92 35.68 14 2.72 2.84 38.52 15 2.74 2.86 41.38 16 2.66 2.78 44.16 17 2.4 2.52 46.68 18 2.4 2.52 49.2 19 2.3 2.42 51.62 20 2.24 2.36 53.98 21 2.12 2.24 56.22 22 1.98 2.1 58.32 23 1.78 1.9 60.22 24 1.7 1.82 62.04 25 1.64 1.76 63.8 26 1.42 1.54 65.34 27 1.32 1.44 66.78 28 1.06 1.18 67.96 29 0.92 1.04 69 30 0.6 0.72 69.72 Enough for now... Cheers, Terry Previous post ---------------------------------------------------------------------------- ------- Hi All, Here are the early raw results of the voltage profiling experiment. One inch sections of the coil were numbered 1,2,...30 with the base section being 1. The secondary was scratched at every inch to gain electrical contact. The profiler had to be held by a tripod since there was no way it could be held by hand. I had to position it, get away for a moment, pull the probe out and take the reading. I tested the probe in the forward and reverse directions and the reading were the same. I retested a single section three times and the reading were extremely consistent. I had to check continuity with a voltmeter when the probe was place to insure the delicate contact was made. I then shorted the cap to insure it was at zero voltage before the reading. very delicate and tedious but fairly tolerable. The coil was driven by a <1 ohm Z signal generator but a 49.8 ohm surface mount resistor was put inline for current sensing. Thus, the generator had a 50 ohm impedance. The frequency was 146.45 kHz. The voltage drop across the resistor was 46.5mV ACrms The generator puts out 0.7071 VACrms, or 1 volt peak, or 2 volts P-P. It is a MAX038 Chip device. The multimeter is an HP34401. The scope is a Tektronix B210. Reading the voltage of the cap with the fancy digital storage scope was child's play. It was consitant and deadly accurate. At these low voltages, the cap should have not drifted at all. >From the above, The input voltage was 0.6606 VACrms at 0.9337mA at 146.45kHz. Exciting pictures of the mess can be found at: http://63.225.104.49/TeslaCoils/Misc/PaulNich/ProfilerPics/ At the moment I have tested sections 22 to 30 and the numbers are as follows. Section 30 is the top. These numbers need the diode drop added still. That number seems to be 0.12 volts. Position Peak Voltage (Vdc) 30 0.60 29 0.92 28 1.06 27 1.32 26 1.42 25 1.64 24 1.70 1.68 1.68 (Repeated 3 times) 23 1.78 22 1.98 1.96 (reversed probe) At this point it was supper time and my knees started to give out. If there are any bumps around 27,26,25, those were the very first readings and things were "uncontrolled" a bit... I have only taken the data and typed it up here so I have not really looked thoughtfully at the numbers yet. I assume they make sense (hope hope). I do note that the steel ruler theory seems to be in serious trouble =:o) I hope to get the rest of the points tonight if the old body can do it. All seems to go very well and the readings seem very good but it is hard work! This is all minutes fresh so forgive any obvious errors. Comments and suggestions or always welcome. Cheers, Terry
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.