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Re: Ultra tiny coils!

Original poster: "Barton B. Anderson" <tesla111@xxxxxxxxxxxxx>

600 MHz!?
150 MHz?

Far too high. If this is the little 5x20mm coil, I'm getting about 20 MHz on the sec and 21 MHz on the pri. Only 5.8% detune which is normal. I noted the sec turns can't be correct (schematic showed 550T and coil page showed 350T). However, .07mm wire must be less than 300T for a 20mm length (without overlapping). I used 285T for calcs (should measure 20 ohms with DC meter or should count 142T per cm). It was interesting to note that when the turns were brought in to what I figure is closer to reality, both circuits were well in tune. The meter used is probably having difficulty with the measurements and this may be better modeled in a capable program.

Accuracy is uncertain, but due to the "tuned" results, it's close.

Courtesy of JAVATC.
The results below for anyone interested with specifics.

Take care,
Bart B.

ALL inputs are cm. ---------------------------------------------------- J A V A T C v.10 - CONSOLIDATED OUTPUT Tuesday, February 08, 2005 9:20:40 PM

Units = Centimeters
Surrounding Inputs:
261.62 = Ground Plane Radius
261.62 = Wall Radius
381 = Wall Height
261.62 = Ceiling Radius
381 = Ceiling Height
Secondary Coil Inputs:
Current Profile = G.PROFILE_LOADED
0.25 = Radius 1
0.25 = Radius 2
1 = Height 1 (1cm above groundplane)
3 = Height 2 (2cm + 1cm above groundplane)
285 = Turns
0.007 = Wire Diameter (cm)
Primary Coil Inputs:
0.35 = Radius 1
0.95 = Radius 2
1 = Height 1 (1cm above groundplane)
1 = Height 2 (1cm above groundplane)
4 = Turns
0.09 = Wire Diameter (cm)
0.00025 = Primary Cap (uF)
Top Load Object Inputs (dimensions & topload or ground connection):
Toroid #1: minor=0.45, major=1.3, height=3.3, topload
Secondary Outputs:
20144.81 [kHz] = Secondary Resonant Frequency
90 [deg°] = Angle of Secondary
2 [cm] = Length of Winding
142.5 = Turns Per cm
0.00018 [cm] = Space Between Turns (edge to edge)
39 [awg] = Recommended Wire Size
4.48 [meters] = Length of Wire
4 = H/D Aspect Ratio
20.06 [ohms] = DC Resistance
10778 [ohms] = Reactance at Resonance
10981 [ohms] = Forward Transfer Impedance
0.085 [mH] = Les-Effective Series Inductance
0.082 [mH] = Lee-Equivalent Energy Inductance
0.09 [mH] = Ldc-Low Frequency Inductance
0.733 [pF] = Ces-Effective Shunt Capacitance
0.68 [pF] = Cee-Equivalent Energy Capacitance
1.257 [pF] = Cdc-Low Frequency Capacitance
0.015 [mm] = Skin Depth
0.511 [pF] = Topload Effective Capacitance
Primary Outputs:
21385.64 [kHz] = Primary Resonant Frequency
5.8 [%] = Percent Detuned
0 [deg°] = Angle of Primary
16.34 [cm] = Length of Wire
0.06 [cm] = Average spacing between turns (edge to edge)
0.1 [cm] = Primary to Secondary Clearance
0.222 [uH] = Ldc-Low Frequency Inductance
0.653 [uH] = Lm-Mutual Inductance
0.147 [k] = Coupling Coefficient
6.8 = Number of half cycles for energy transfer at K
0.16 [uS] = Time for total energy transfer (ideal quench time)


Tesla list wrote:

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Derek,

Your super tiny coils are really cool!

You say 0.5pF at 140nH for the secondary. Ok, have been ill and have probably been taking too much cold "medicine" ;o) But:

if Fo = 1 / (2 x pi x SQRT(L x C)) = 1 / (2 x pi x SQRT(140e-9 x 500e-15)) = 601e6

I get an Fo frequency of 601MHz!!! That would put them far beyond any frequency I have every heard of for Tesla coils by about 10X!! Does that sound right for the Fo frequency?

What is the primary voltage and BPS rate ( just "roughly")? I should have plenty of power supplies in that range ;-))

I punched it into E-Tesla6 that does do 'mm' range stuff ;-) "Very" rough, but I did get Fo's in the 150MHz range!!

I would be surprised if ordinary poly caps work at all at that frequency... Might want to go to mica...

Very interesting stuff!!



At 05:41 PM 2/8/2005, you wrote:

>THOSE ARE SUPER COOL!!! Sell me one!!!!!!!!!!

Sorry, I'm not going to sell you one, that's FAR to easy.

I will of course give you any information you require to make one for

The Monopolar?? And Bipolar coils took me about 3 Hours to build each,
(excluding the 2KV PSU)

The Magnifier took me about twice as long, mostly trying to get it some
where in tune. I'm still not happy, but I've run out of small poly caps. So
it's the best I can do with what I have to hand.

The resonant peak of the non-magnifier coils is pretty wide, So tuning is
really easy once you are in the right ballpark. I didn't use any
calculations at all, I'm afraid that most of the TC design programs are a
long way out from reality with such small coils, probably due to stray
inductance and capacitance. When your topload is 0.5pF yes 500fF and your
primary is 140nH, exact measurement becomes tricky.

Have fun building them.. You wont upset the neighbours. You can run them on
your desk. You don't need an RF earth (any bigger than the SLA that powers
them). They cost very little to build and the only dangers are RF burns and
a nasty bite from a 1nF primary cap at about 2Kv

They are almost the perfect TC, if only they gave 10' sparks not 15mm sparks