Tesla's "COIL FOR ELECTRO-MAGNETS".

[conradelektro]

I made new tests with the monofilar and bifilar pan cake coils.

A new video http://youtu.be/spQ9yLdb7v4 (measuring self resonance frequency with a "two turn exciter coil", about the same results as in the first video, see the attached circuit diagram of the measurement)


Then I made a "pick up coil test" with my vertical magnet spinner (see the attached photo). I showed the vertical spinner here

http://www.overunity.com/13852/self-accelerating-reed-switch-magnet-spinner/msg379520/#msg379520
http://www.overunity.com/13852/self-accelerating-reed-switch-magnet-spinner/msg379723/#msg379723
http://www.overunity.com/13852/self-accelerating-reed-switch-magnet-spinner/msg379943/#msg379943 (final drive circuit)

Remember the vertical magnet spinner has very little torque (strength) and therefore can be slowed down quite easily with a "pick up coil".

Both pan cake coils were put at exactly 18 mm distance from the spinning magnet (always only one coil in place) and the output over a 1 Ohm resistor was measured with the oscilloscope (true RMS) and the slow down of the magnet spinner was noted.

Both coils gave the same results (vertical magnet spinner was run with 15V from the lab power supply and always drew the same Amperage):

- Output over 1 Ohm resistor (at 18 mm distance from spinning magnet) was 34,4 mV (true RMS)
- Slowdown of spinning magnet: from about ~30 Hz to ~25 Hz (~1800 rpm to ~1500 rpm).

The magnet spinner was always run for several minutes to let it settle at the final speed.


Concerning the magnetic field produced by the two pancake coils:

Both coils did not produce a measurable magnetic field at 1 Watt or 10 Watt (compass and hall sensor A1101 http://www.allegromicro.com/Products/Magnetic-Digital-Position-Sensor-ICs/Hall-Effect-Unipolar-Switches/A1101-2-3-4-6.aspx). The coils soon became hot. Therefore, any meaningful "magnetic field test" has to wait till I move on to solenoid type coils with many turns of wire.


Concerning synchro1: it would be best if synchro1 stops posting in this thread, I certainly will not react to any of his posts. He has outdone himself and he annoys me very much.

Greetings, Conrad

[Bob Smith]

Here's the "Old Scientist" tuning a bifilar coil LC tank with a variable air capacitor:

http://www.youtube.com/watch?v=2CcxJogghxY

He concludes that a bifilar coil has strong harmonics but is not influenced in the same way a standard or parallel LC tank circuit would be, due to the "resonance between the capacitor and the self capacitance of the coil".


In other words, the virtual LCC tank resonance of the bifilar tank is not as easily influenced by interference like a standard LC tank, and more stable!

Yes, isn't this why the swbf coil is part of Tesla's Magnifying Transmitter? ie., there won't be reactive losses with a secondary.
Following your thread with interest, Synchro.
Bob

[synchro1]

@Conradelektro,

Quote from Conradelelktro:

"Concerning synchro1: it would be best if synchro1 stops posting in this thread, I certainly will not react to any of his posts. He has outdone himself and he annoys me very much".

Response from Synchro1:

Tut-Tut! Hurrrumph!

[MileHigh]

Hi Conrad,

I looked at your new clip.  There is one cautionary note I want to mention.  The axis of your exciter coil and the axis of your main coil are at 90 degrees to each other.  We know that with this coil-to-coil geometry you are minimizing the interaction between the two coils because the magnetic lines of force from one coil will not interact with the wire turns of the other coil.  Of course the reality is that there will still be a weak interaction, and this weak interaction is still enough to excite the coil under test to observe the resonance frequency.  I don't want to prejudge you, you may have done this intentionally.  If you did not do this intentionally then note that you always have to try to visualize how the magnetic field from one coil interacts with the magnetic field from another coil when you are planning to do a test or build something.  Geometry is of prime importance and it can never be overlooked when you work with coils that are magnetically coupled to each other.

This issue is one of my pet peeves.  I have seen people that have been experimenting for years that are seemingly oblivious or ignorant of this issue.  This is a basic concept that must be understood by all experimenters working with coils and magnetic fields.  Skycollection is one of the experimenters that comes to mind for this issue.  I have seen several clips made by him with coils in physical arrangements that don't make any sense.  I don't care about being the "bad guy" when it comes to stating this.  If you don't speak up and correct each other and encourage each other to learn, then there is no progress and ongoing collective ignorance.  This issue is very similar to people adding magnets to magnetically bias some kind of transformer circuit.  In the vast majority of cases it makes no sense at all and actually degrades the performance of the transformer circuit.

MileHigh

[synchro1]

@Conradelektro,


You have to place the bifilar coil over an iron plate to get it to work as an electromagnet.