Tesla's "COIL FOR ELECTRO-MAGNETS".

[conradelektro]

I want to reproduce the experiment which Itsu shows in his video http://www.youtube.com/watch?v=syxL4f2OsPg (resonance with magnet spinner, speed up under load).

Luckily I found an old "Bedini coil" in one of my boxes with stuff from past experiments. (See the attached photo.)

The coil is bifilar (one wire 0.2 mm the other 0.3 mm diameter magnet wire, in series) and has many turns. If I do a calculation with this calculator http://www.66pacific.com/calculators/coil_calc.aspx I get about 3200 turns (I have forgotten the number of turns).

The coil parameters (measured with a 4 turn exciter coil and my function generator plus scope as I have learned with the pan cake coils, impedance was measured with my LCR meter and calculated from "parallel LC circuit" resonance tests):

DC resistance about 97 OHm
length 52 mm
diameter 38 mm
core 10 mm (hole in core only 7 mm)

air core
measured impedance:  at 100 Hz    --> 168 mH
                                     at 1 KHz      --> 176 mH
                                     at 10 KHz    -->   46 mH
self resonance at 4600 Hz
self capacitance            with assumed 170 mH   --> 7 nF
                                     (with assumed   44 mH   --> 26 nF)
experimental impedance:          810 Hz resonance with 0.22 µF cap     --> 172 mH
                                               390 Hz resonance with 0.986 µF cap   --> 169 mH
                                               120 Hz resonance with 10.08 µF cap   --> 174 mH
steel bolt as core
measured impedance:  at 100 Hz         --> 520 mH
                                    at 1 KHz         --> 320 mH
                                    at 10 KHz       -->   44 mH
self resonance at 4000 Hz
self capacitance            with assumed  520 mH   --> 3 nF
                                   (with assumed   44 mH   --> 35 nF)
experimental impedance:          520 Hz resonance with 0.224 µF cap --> 418 mH
                                               225 Hz resonance with 0.986 µF cap   --> 507 mH
                                                 70 Hz resonance with 10.08 µF cap   --> 512 mH

And if you look at the resonance frequency of an LC circuit with this coil and a 10 µF capacitor, one sees that it would resonate at 120 Hz (air core) or 70 Hz (steel bolt core).

I can realise these speeds (7200 rpm and 4200 rpm) with my new "12 DC motor ring magnet spinner" to recreate the resonance condition Itsu is showing (LC circuit resonating at 70 Hz or 120 Hz: coil + 10 µF cap).

The new magnet spinner is almost finished with a professional coupling (and this coil is ready, also the 10 µF cap). But I will not have time till Monday to do any experiments.

In the meantime, what do the experts think? Can it be done like this, should I try this and what are the difficulties and pitfalls?

I do not have a matching monofilar coil. The "speed up under load test" would then only be with this big fat bifilar coil.

Greetings, Conrad

[synchro1]

@Conradelektro,

Now your experiments are regaining interest and relevency. Let me just point out that multiple output coils split the output along with the acceleration effect! This is the bane of the Thane Heins generator. Nevertheless, it's a mistake to hide from the effect and pretend it's meaningless! I believe you'll return to the "Synchro Coil" research with renewed insights. It would be very simple to slip a stack of coupled radial magnets into the coil core, in place of that metal bolt, after you're through licking your wounds sufficiently.

[MileHigh]

Conrad:

It looks like you have all of the pieces to set up some great tests.

You notice how the measured inductance drops down a lot at 10 KHz.  I am not sure why and I am a bit surprised, especially for the air core.  So you should avoid your testing at the 10 KHz self-resonant frequency and stick to lower frequencies.

Looking forward to seeing the new magnet spinner configuration.

I do not have a matching monofilar coil. The "speed up under load test" would then only be with this big fat bifilar coil.

The good news is that if you use just one of the wires in your coil (the thicker wire) you will have a comparable, but not identical coil.  The geometry will be the same, but the inductance will measure about 1/4 the series bifilar version.   So you can still observe how that monofilar coil responds to it's own resonant condition and it will be comparable with the bifilar with the understanding that the inductance and resonant frequency has changed.  You just have to dial up the correct angular frequency on your magnet spinner.

Have fun!

MileHigh

[conradelektro]

You notice how the measured inductance drops down a lot at 10 KHz.  I am not sure why and I am a bit surprised, especially for the air core.  So you should avoid your testing at the 10 KHz self-resonant frequency and stick to lower frequencies.

The good news is that if you use just one of the wires in your coil (the thicker wire) you will have a comparable, but not identical coil.  The geometry will be the same, but the inductance will measure about 1/4 the series bifilar version.   So you can still observe how that monofilar coil responds to it's own resonant condition and it will be comparable with the bifilar with the understanding that the inductance and resonant frequency has changed.  You just have to dial up the correct angular frequency on your magnet spinner.

@MileHigh:

I just measured the inductance of one wire of my big Bedini coil,

it is 42 mH (air core) and 132 mH (steel bolt core) same for both wires.

Great, you predicted the 1/4 inductance.

Inductance of one wire also drops at higher frequencies:

air core: 43 mH at 1 KHz and 11 mH at 10 KHz

steel core: 80 mH at 1 KHz and 10 mH at 10 KHz.


This calculator at http://www.1728.org/resfreq.htm then computes a resonance frequency of 138 Hz with a 10 µF cap (steel bolt core). And I hope that I can also do 138 Hz (8280 rpm).

But I will not be able to do 248 Hz (14880 rpm) with one wire air core.


The possible tests I envision (10 µF in LC circuit):

70 Hz --- bifilar, steel bolt core

120 Hz --- bifilar, air core

138 Hz -- monofilar (half coil), steel bolt core

248 Hz -- monofilar (half coil), air core not possible


My new magnet spinner should do up to 150 Hz (about 10.000 rpm). The 12 V motor should do up to 12300 rpm at 18 Volt (even 14800 with little load), but I expect some vibrations, why I do not dare to hope for more than 10.000 rpm).

Self resonance is at 4600 Hz (bifilar air core) and 4000 Hz (bifilar steel bolt core). I did not yet measure self resonance for one wire (half coil).

I did impedance measurements at 10 KHz (one of the settings of my LCR-meter) several times and also the LC-circuit resonance tests with several capacitors showed that the impedance drops rapidly with frequencies higher than 1 KHz. But I will only need the very low frequencies (70 Hz to 132 Hz).

Is it correct that high impedance coils do strange things at high frequencies (specially beyond their self resonance frequency)? 10 KHz (where the LCR-meter shows low impedance) is twice the self resonance frequency, the coil should do funny things?

Greetings, Conrad

[synchro1]

@Conradelektro,

Quote from Conradelektro,

"I want to reproduce the experiment which Itsu shows".

Itsu is running multiple magnets on a high speed precision VCR bearing! Your bipolar rpm has to multiply by the number of Itsu's rotor magnets to equal the same frequency!

How come your so smart know it all OU educator "Milehigh" can't tell you that!

Try the bearingless tube spinner on a ball bearing, with your original relay sensor circuit, placed on a concave cosmetic mirror. Don't be afraid of shattering the tube magnet at 25k. There's no hazard at that slow a speed. We get upwards of 300k before we encounter those kinds of problems. You can always put a PVC coupling around the setup, like I do, for extra precaution! Pay close attention to this: DLE=(Delayed Lenz Effect)

Quote from JLN:

"In the case of the generators, the increase of the turn rate is produced by the DLE when the devices are loaded above a "critical minimum frequency". Below the critical minimum frequency the DLE coil will produce deceleration as per any conventional Lenz generator coil. Coil frequency dictates coil impedance which is a critical factor in producing generator DLE and on-load system acceleration".

I call JLN's "critical minimum frequency" the "Lenz acceleration threshold speed".

JLN is motoring his bipolar spinner at 500 hertz which translates as 30,000 rpm. for his "Lenz delay test". Don't be disappointed if you get merely a slowing down effect at 10,000 rpm with a diametric!

Study JLN's DLE-Test-18 before you proceed:

http://jnaudin.free.fr/dlenz/DLE19en.htm