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Registered Member #50
Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324
So the first light of this coil was quite anti-climactic. The most I could squeeze out of it was about 5 or 6". This is the part I hate most about tesla coiling, he effort put into building and then the tuning frustration. I have a capacitor thats nicely matched to the transformer. So whats everyones first thing they do when tuning a coil? I have an oscilloscope but no frequency generator. Does anyone know an Easy DIY func. Generator? That might make it easier...
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
If you hate tuning the system and trying to find its optimal point by hit or miss evaluation, the other choice is to get the equipment you need to make measurements. Having an oscilloscope is important, and you can get a good old HP tube generator for pretty cheap, and you're set for the most part. I've spent a lot of money on gear for measurement and it hasn't been easy or cheap. Scope, generator and LCR meter are the essentials in this game if you want big sparks. If you want transfer functions, power, and analysis, you have to bite a pretty big bullet and get a DSO of some sort. I've even considered buying a Spectrum Analyzer kit for $300.
This is an expensive hobby, and if you can get away with manual tuning I'd be happy with that, otherwise you're in for some nasty sticker shock.
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
I wasn't very successful without an LCR meter either, but there are ways of manual tuning that are pretty fast, like choosing a turn then jumping 1 turn out and 1 turn in and seeing what does better.
Knowing your supply, capacitor, pri and sec. are the major keys, and that's where LCR meters excel. By use of the LCR meter, simulation, and careful testing, you'll be able to get some nice long arcs from that supply, close to 5 feet or more.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
I've never owned an LCR meter and have sparked my own height and then some. I found an analog scope and signal generator were about all I needed. Tesla coiling is a pretty cheap hobby, compared to motor racing or yachting.
Bart's JAVATC can probably tune your coil by computer calculation better than most test equipment.
You will have to figure it out (pretty easy) and measure things pretty carefully with a ruler. But once the input numbers are correct, the primary tuning and all outputs will be very accurate.
The program is pretty easily capable of calculating coil parameters better than most typical test equipment can measure!! It's also free, and just a mouse click away
Registered Member #50
Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324
Ok, so JavaTC newb here...I spent about an hour and measured everything pretty accurately...but when I told it to auto tune it said to check my primary parameters and to possibly change my capacitor value. So I'm going to post my inputs of the whole thing WARING: Its a lot. Any input on tuning etc. would be appreciated.
J A V A T C v.10 - CONSOLIDATED OUTPUT Monday, March 26, 2007 8:25:36 PM
-----------------------------------------
----------- Secondary Outputs: -----------------------------------------
----------- 830.98 kHz = Secondary Resonant Frequency 90 deg° = Angle of Secondary 48 cm = Length of Winding 9.87 cm = Turns Per Unit 0.55879 mm = Space Between Turns (edge to edge) 113.38 m = Length of Wire 6.3:1 = H/D Aspect Ratio 12.04 ohms = DC Resistance 12558 ohms = Forward Transfer Impedance 12445 ohms = Reactance at Resonance 0.164 kg = Weight of Wire 2.384 mH = Les-Effective Series Inductance 2.259 mH = Lee-Equivalent Energy Inductance 2.519 mH = Ldc-Low Frequency Inductance 15.39 pF = Ces-Effective Shunt Capacitance 14.325 pF = Cee-Equivalent Energy Capacitance 23.356 pF = Cdc-Low Frequency Capacitance 0.115 mm = Skin Depth 10.1 pF = Topload Effective Capacitance 45.3 ohms = Effective AC Resistance 275 = Q
-----------------------------------------------
----- Primary Outputs: -----------------------------------------
----------- 790.21 kHz = Primary Resonant Frequency 4.91 % = Percent Detuned 0 deg° = Angle of Primary 61.2 cm = Length of Wire 0.9 cm = Average spacing between turns (edge to edge) 5.19 cm = Primary to Secondary Clearance 0.429 µH = Ldc-Low Frequency Inductance 0.01611 µF = Cap size needed with Primary L (reference) 2.277 µH = Lead Length Inductance 3.641 µH = Lm-Mutual Inductance 0.111 k = Coupling Coefficient 9.01 = Number of half cycles for energy transfer at K 5.66 µs = Time for total energy transfer (ideal quench time)
-------------------------------------------
--------- Transformer Inputs: ------------------------------------------
---------- 120 [volts] = Transformer Rated Input Voltage 15000 [volts] = Transformer Rated Output Voltage 60 [mA] = Transformer Rated Output Current 60 [Hz] = Mains Frequency 120 [volts] = Transformer Applied Voltage 0 [amps] = Transformer Ballast Current 0 [ohms] = Measured Primary Resistance 0 [ohms] = Measured Secondary Resistance
--------------------------------------
-------------- Transformer Outputs: -----------------------------------------
----------- 900 [volt*amps] = Rated Transformer VA 250000 [ohms] = Transformer Impedence 15000 [rms volts] = Effective Output Voltage 7.5 [rms amps] = Effective Transformer Primary Current 0.06 [rms amps] = Effective Transformer Secondary Current 900 [volt*amps] = Effective Input VA 0.0106 [uF] = Resonant Cap Size 0.0159 [uF] = Static gap LTR Cap Size 0.0277 [uF] = SRSG LTR Cap Size 166 [uF] = Power Factor Cap Size 21213 [peak volts] = Voltage Across Cap 75000 [peak volts] = Recommended Cap Voltage Rating 3.38 [joules] = Primary Cap Energy 3972.6 [peak amps] = Primary Instantaneous Current 110.1 [cm] = Spark Length (JF equation using Resonance Research Corp. factors)
----------------------------------------
------------ Rotary Spark Gap Inputs: ------------------------------------------
---------- 0 = Number of Stationary Gaps 0 = Number of Rotating Electrodes 0 [rpm] = Disc RPM 0 = Rotating Electrode Diameter 0 = Stationary Electrode Diameter 0 = Rotating Path Diameter
----------------------------------------
------------ Rotary Spark Gap Outputs: -----------------------------------------
----------- = Presentations Per Revolution [BPS] = Breaks Per Second [kmh] = Rotational Speed [ms] = RSG Firing Rate [ms] = Time for Capacitor to Fully Charge = Time Constant at Gap Conduction [ms] = Electrode Mechanical Dwell Time [%] = Percent Cp Charged When Gap Fires [peak volts] = Effective Cap Voltage [joules] = Effective Cap Energy [peak volts] = Terminal Voltage [power] = Energy Across Gap [cm] = RSG Spark Length (using energy equation)
---------------------------------------
------------- Static Spark Gap Inputs: ------------------------------------------
---------- 2 = Number of Electrodes 0.3 [cm] = Electrode Diameter 1.3 [cm] = Total Gap Spacing
-----------------------------------------
----------- Static Spark Gap Outputs: -----------------------------------------
----------- 1.3 [cm] = Gap Spacing Between Each Electrode 21213 [peak volts] = Charging Voltage 20766 [peak volts] = Arc Voltage 31948 [volts] = Voltage Gradient at Electrode 15974 [volts/cm] = Arc Voltage per unit 97.9 [%] = Percent Cp Charged When Gap Fires 9.217 [ms] = Time To Arc Voltage 108 [BPS] = Breaks Per Second 3.23 [joules] = Effective Cap Energy 671982 [peak volts] = Terminal Voltage 351 [power] = Energy Across Gap 129.7 [cm] = Static Gap Spark Length (using energy equation)
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Your resonant frequency is too high, so with the capacitor chosen to draw optimum power from the transformer, you only have about one primary turn. I guess you wound the secondary with too heavy a gauge of wire, or on too small a diameter of tube.
Registered Member #50
Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324
Well both wire gauges on the Larger Coil/smaller coil are the same. For my first Calculations I used teslacad then I used JavaTC. I'm not exactly sure of the wire gauge... So I'm measuring with some rough calipers. Just to clear up any possible misunderstanding, This is all measured in CENTIMETERS. Should I try the bigger coil? I think the wire gauge is about 25 or 26 gauge. I don't know how I'd figure that out....
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Coil decision
