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Re: question about "lambda" (fwd)
---------- Forwarded message ----------
Date: Fri, 24 Aug 2007 23:35:26 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: question about "lambda" (fwd)
Hi Matthew,
Well, the 12" diameter changes everything. Here is what you stated when
you sent me specs:
> primary coil is helical with 16 windings of 6AWG copper wire spaced
> .5in apart with 12ft diameter
So, I was thinking a 12 foot diameter coil, and given you were using a
4pF cap size, well, I figured you were doing something very different.
But, it seems just a typo, but it does change my perspective greatly.
BTW, for the probe, horizontal with the center of the toroid and between
3 to 6 feet away to start. Once you find your fundamental, then move the
probe as far away as possible but ensure you can make out the resonant
frequency peak well. The further away you get, the lower the amplitude
on the scope, and the lower the amplitude, the larger radius of the
peak. Try to keep a sharp peak without loading the coil with your probe
(that's the basic idea).
For the inductance you measured, your at about 755 turns on the sec with
22 awg. With the topload and primary in place, your fundamental resonant
frequency is 387 kHz (lower than your thought, eh?).
With the 15/60 (two 15/30's), a decent cap size to use is .0167uF.
That's much larger than your 4pF size which is way off base by a
magnitude or two). You could build a decent MMC using 2 strings of 18
caps per string (of the .015uF CD caps).
Using that value of cap (0.167uF), your primary needs to be near 9.26uH,
or 4.6 turns with your current 1/2" spacing. Javatc recommended 0.129
coupling ratio. Given that value, your primary position of coil
components should look something like this:
http://www.classictesla.com/temp/mb1.gif
For actual dimensions, see the Javatc data below:
Helical final positions don't quite look as good as this (the helical
often needs to be lowered), but your helical primary seems to have a
wide enough proximity (3.9 inches) that you are able to actually raise
the helical to a "nice looking vertical position". Pleasing to the eye!
Good job with that, it's not often I see a correct k value at this position.
Anyway, this is very near the positions of all components that would
work well. Your double 15/30 NST's can do much better in the Static
spark gap arena. Use 6 pipes of 1.25" diameter spaced at a total gap of
0.25". This equates to .05 inch per electrode (50 mils). I like to epoxy
a single pipe vertically inside a 4" tube and let it cure. Then epoxy in
place the second pipe and place a feeler gauge between the new pipe and
the first pipe allowing gravity to hold it down on the pvc and against
the feeler gauge while it cures. I do this same procedure with each pipe
which ensures a precise distance between each electrode. Add a decent
fan and you've got a "very" good static gap. You might expect 50" sparks
on this coil configuration, but because the primary surge impedance will
be low, there will be a little more losses, so maybe 45" would be realistic.
I've included below the Javatc consolidated output below for your
reference which shows my inputs and misc info.
Again, thanks for clarifying the primary.
Take care,
Bart
BTW, I just realized helical primary's can take a long time to run when
using the "desired coupling" feature in Javatc. I guess I'll have to
work on efficiency in that area to get the crunching time down to a
reasonable level.
--------------------------------------------------------------------------
J A V A T C v.11 - CONSOLIDATED OUTPUT
Friday, August 24, 2007 10:46:21 PM
Units = Inches
Ambient Temp = 68°F
----------------------------------------------------
Surrounding Inputs:
----------------------------------------------------
100 = Ground Plane Radius
100 = Wall Radius
150 = Ceiling Height
----------------------------------------------------
Secondary Coil Inputs:
----------------------------------------------------
Current Profile = G.PROFILE_LOADED
2 = Radius 1
2 = Radius 2
20 = Height 1
38 = Height 2
755 = Turns
22 = Wire Awg
----------------------------------------------------
Primary Coil Inputs:
----------------------------------------------------
6 = Radius 1
6 = Radius 2
19.415 = Height 1
22.513 = Height 2
4.6322 = Turns
6 = Wire Awg
0.0167 = Primary Cap (uF)
30 = Total Lead Length (lead wires from and to cap)
0.2 = Lead Diameter
----------------------------------------------------
Top Load Inputs:
----------------------------------------------------
Sphere #1: horz=8, vert=8, height=44, topload
----------------------------------------------------
Secondary Outputs:
----------------------------------------------------
387.15 kHz = Secondary Resonant Frequency
90 deg° = Angle of Secondary
18 inch = Length of Winding
41.9 inch = Turns Per Unit
-0.00151 inch = Space Between Turns (edge to edge)
790.6 ft = Length of Wire
4.5:1 = H/D Aspect Ratio
12.76 ohms = DC Resistance
26285 ohms = Forward Transfer Impedance
26061 ohms = Reactance at Resonance
1.54 lbs = Weight of Wire
10.714 mH = Les-Effective Series Inductance
9.962 mH = Lee-Equivalent Energy Inductance
11.576 mH = Ldc-Low Frequency Inductance
15.774 pF = Ces-Effective Shunt Capacitance
14.419 pF = Cee-Equivalent Energy Capacitance
25.265 pF = Cdc-Low Frequency Capacitance
4.31 mils = Skin Depth
9.573 pF = Topload Effective Capacitance
82.3 ohms = Effective AC Resistance
317 = Q
----------------------------------------------------
Primary Outputs:
----------------------------------------------------
387.17 kHz = Primary Resonant Frequency
0.01 % low = Percent Detuned
90 deg° = Angle of Primary
14.55 ft = Length of Wire
0.507 inch = Average spacing between turns (edge to edge)
3.906 inch = Proximity between coils
1.42 inch = Recommended proximity between coils
9.258 µH = Ldc-Low Frequency Inductance
0.0167 µF = Cap size needed with Primary L (reference)
0.861 µH = Lead Length Inductance
42.571 µH = Lm-Mutual Inductance
0.13 k = Coupling Coefficient
0.129 k = Recommended Coupling Coefficient
7.69 = Number of half cycles for energy transfer at K
9.83 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
----------------------------------------------------
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
3.76 [joules] = Primary Cap Energy
901 [peak amps] = Primary Instantaneous Current
43.4 [inch] = Spark Length (JF equation using Resonance Research Corp.
factors)
----------------------------------------------------
Static Spark Gap Inputs:
----------------------------------------------------
6 = Number of Electrodes
1.25 [inch] = Electrode Diameter
0.25 [inch] = Total Gap Spacing
----------------------------------------------------
Static Spark Gap Outputs:
----------------------------------------------------
0.05 [inch] = Gap Spacing Between Each Electrode
21213 [peak volts] = Charging Voltage
19414 [peak volts] = Arc Voltage
34822 [volts] = Voltage Gradient at Electrode
77654 [volts/inch] = Arc Voltage per unit
91.5 [%] = Percent Cp Charged When Gap Fires
10.762 [ms] = Time To Arc Voltage
93 [BPS] = Breaks Per Second
3.15 [joules] = Effective Cap Energy
660685 [rms volts] = Terminal Voltage
292 [power] = Energy Across Gap
47.9 [inch] = Static Gap Spark Length (using energy equation)
Tesla list wrote:
>---------- Forwarded message ----------
>Date: Fri, 24 Aug 2007 15:58:39 -0500
>From: Matthew Boddicker <shmerpleton_town@xxxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: question about "lambda" (fwd)
>
>This is Matthew again,
>
>the primary coil is helical and 12 inches in diameter.
>
>So if I have a spherical top load, where do I hold the oscillascope probe?
>
>Thanks,
>Matthew Boddicker
>
>
>
>
>>From: "Tesla list" <tesla@xxxxxxxxxx>
>>To: tesla@xxxxxxxxxx
>>Subject: Re: question about "lambda" (fwd)
>>Date: Thu, 23 Aug 2007 20:04:26 -0600 (MDT)
>>
>>
>>---------- Forwarded message ----------
>>Date: Thu, 23 Aug 2007 18:36:49 -0700
>>From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
>>To: Tesla list <tesla@xxxxxxxxxx>
>>Subject: Re: question about "lambda" (fwd)
>>
>>Hi Matthew,
>>
>>Tesla list wrote:
>>
>>
>>
>>>This is exactly what I needed, thank you! So with the wavelength being
>>>
>>>
>>taken
>>
>>
>>>into consideration, where would be good spot for the primary coil to be?
>>>
>>>
>>I
>>
>>
>>>am currently using a helical primary, but hope to switch to a pancake
>>>primary soon.
>>>
>>>
>>>
>>>
>>First, the primary should be at the opposite end of the hv end.
>>Secondly, coupling will identify it's placement with a fixed geometry.
>>Whatever your current helical coil is, you'll need to get the coupling
>>to a usable level. If the helical is a wide as I think it is, your
>>coupling may actually be very low (can you confirm the primary diameter
>>again?). Often, when helical's are built, the secondary is adjusted
>>above it. This occurs because the coupling was too high and coil to coil
>>distance is the only thing that can fix that. But, if the helical is
>>made wide enough, then it can be raised higher and higher.
>>
>>
>>
>>>Also, is there any tips on using a oscillascope to find the frquency of
>>>
>>>
>>the
>>
>>
>>>secondary? I've tried it before, but the oscillascope wouldn't give a
>>>
>>>
>>clear
>>
>>
>>>reading. I though I heard somewhere that a signal generator could be used
>>>
>>>
>>in
>>
>>
>>>conjunction with a oscillascope somehow.
>>>
>>>
>>>
>>>
>>Yes, use a signal generator connecting the base of the secondary to the
>>generator output. You'll then be able to read the signal on the
>>oscilloscope. Place the scope probe horizontal with the toroid and about
>>1 coil length away with maybe a 4" piece of wire in the probe end to act
>>as an antenna. Adjust the signal generator frequency until you see
>>voltage amplitude rise. The point at which the amplitude is greatest is
>>the fundamental frequency. It's good to calc your fundamental first,
>>then adjust the generator below that frequency by some amount before you
>>start adjusting the generator. It's good to do this with everything in
>>position (primary and topload).
>>
>>Take care,
>>Bart
>>
>>
>>
>>
>>
>
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