Tesla's "COIL FOR ELECTRO-MAGNETS".

[MileHigh]

Quoting Farmhand about this thread from an EF thread:

http://www.energeticforum.com/renewable-energy/14165-solenoid-electromagnet.html#post233920

Please just ignore the posts by Synchro and Milehigh, they are extremists.

Farmhand's comment about my postings in this thread is pure junk trash talk.  My comments in this thread are sincere and real and they should not be ignored.  They are not extremest at all.  The guy has some issues.

Here is what I think the claims are saying. If the voltage is too low, then the distance between the capacitor "plates" is too great for the capacity to be effectively used.
ie. If the conductors have insulation 5 mm thick then using 1 volt won't utilize the capacity very well and the capacity will not then contribute to the lowering of the resonance frequency. Kinda like trying to use 1 volt with a HV parallel plate air capacitor with 10 mm spacing between the plates, it won't work very well.

It makes sense to me.

Farmhand's comments in fact make no sense at all.  Trying to draw a relationship between the capacitor voltage and the separation between the wire conductors (a.k.a. "plates") makes no sense at all.  There is no real relationship between the voltage and the separation, it's just a speculation that is completely off base.  The notion that "low voltage won't 'use' the capacity and the the capacity won't contribute to the lowering of the resonance frequency" is dead wrong.  The effect of the capacitance on the coil is completely independent of the voltage.

Kinda like trying to use 1 volt with a HV parallel plate air capacitor with 10 mm spacing between the plates, it won't work very well.

The above statement by Farmhand is a completely nonsensical statement.  Again, the idea that putting only one volt across a high-voltage capacitor "won't work very well" is ridiculous, it will work just fine.

What's also very clear in reading the EF thread called "The Solenoid/Electromagnet" is that there are indeed many misconceptions about the Tesla coil and people simply want to believe that the coil has some fantastical properties just because Tesla's name is attached to it.  A thread like this one on OU is worth reading and thinking about.  This reflex among Tesla enthusiasts that says, "whatever Tesla did must be fantastic and amazing and ahead of its time" is clearly the wrong way of going about things.  You should not prejudge something to be great.  Rather, do the investigation yourself with an open mind without preconceiving anything ahead of time.

MileHigh

[sparks]

   I agree that alot if not all public information regarding Tesla's work are limited to his development of alternators-transformers and development of the dynamic capacitor.   By this imagine that you are able to dump a thousand horsepower into something.  That would be the work of a thousand horses for an hour.  This device fits in a suitcase.   You then transport the briefcase to your car.   There the oscillations are damped and you get your thousand horsepower hours out as you drive around town.  The Steven Marks device is very similar to the Tesla dynamic capacitor.   It is a dynamic capacitor.  It needs to be charged.   It's energy density makes solid hydrogen density about as dense as a cup of water at room temperature. 

[MileHigh]

More responses to Farmhand in the EF thread called "The Solenoid/Electromagnet."

The self capacitance is related to the voltage applied in Tesla's coil for
Electro-Magnets due to the reasons I outlined about the capacitor plate
separation. Some people who claim to be quite smart tried to deny that.
But it is true and it fits conventional knowledge and is logical.

Again, this is wrong.  The self-capacitance is related to the geometry of the coil and the permittivity of the dielectric insulation between the windings.  It is not related to the voltage applied.  The voltage applied will determine how much energy can be stored in the capacitance.  This is not to be confused with capacitance and inductance interacting at a given frequency to cancel each other out.  This cancellation effect will take place independent of the applied voltage.

So to properly tune a Coil for electro-magnets, the voltage to be used is also
a consideration. A coil wound for effect at 100 Khz using 10 000 volts will not
work the same if 10 volts is used due to the capacitor plate separation
(thickness of insulation or distance between turns) causing the secured self
capacitance to be less.

One more time, Farmhand is wrong.  If you excite the coil with a 100 KHz, 10,000 Vrms signal to get the self-cancellation effect, then you can excite the same coil with a 100 KHz, 10 Vrms signal and you will get exactly the same self-cancellation effect.

When he says, "due to the capacitor plate separation (thickness of insulation or distance between turns) causing the secured self capacitance to be less," he is wrong again.   We know that the capacitor plate separation is a constant.  Therefore the self-capacitance will be a constant.   The self-capacitance does not change with voltage like Farmhand seems to be suggesting.

Anybody that doubts me can look up capacitance and see how a basic capacitor is constructed with two metal plates separated by a certain distance with the separation filled with a dielectric material with a certain permittivity.  You will not find any voltage variable that comes into play to determine the capacitance.  Don't get thrown off in your understanding of the basic building blocks of electronics because this has the potential to corrupt all of your subsequent learning.

This is evidenced by the way Radio coils are spaced to reduce self capacitance.

The above is a comment that does not make any sense.  The self-capacitance in radio coils will be ignored, assuming that we are looking at the example of an early 20th century AM radio.  The coils in an AM radio are all paired with capacitors or variable capacitors to make LC resonators.  The manufacturers of the coils for use in radios and the designers of radios were never concerned about the insignificant self-capacitance of their coils.  They were designing LC resonators for radios using external capacitors and the self-capacitance of the coils was never even considered.   This is another example of this phenomenon of reading too much into the patent like I have already stated.

For what it's worth, radio coils are normally spaced in a way to avoid mutual coupling between coils.  So it's the form of the external magnetic field outside the coil and possible undesirable mutual coupling and not the self-capacitance that is the prime consideration for the spacing and placement of coils inside an AM radio.

People can dispute whatever they like but time will tell all truths.

You sure as hell are right about that one.

Don't listen to the extremists. They avoid the valid points and dwell on, "it has
no uses so the patent is pointless", or, "this coil makes free energy".

I am not an extremist, I am a practical realist.  Nor am I ignoring any valid points.  Right now the patent is next to pointless.  If you want an LC resonator you pick a coil and a capacitor to make your resonator, you don't need to investigate a self-resonating coil.  A resonator designed with separate L and C components will be more stable and superior to relying on a coil's self-capacitance.  Beyond that, nobody has offered up a practical application for this "series bifilar" coil and the question was posed by me on this forum more than a month ago.

You want even better advice?  Don't listen to people that you have some doubts about.  If you are not getting the right feeling or something doesn't seem quite right, then do the research for yourself if you are capable.   Trust your instincts and be honest with yourself about your ability to make these kinds of technical judgement calls.  Another possibility is to bootstrap yourself up the learning curve.   Or perhaps consulting with people that you do have a good feeling about and believe that they are competent with respect to the subject matter at hand would be another way to go.

MileHigh

[MileHigh]

More comments on Farmhand's posting on EF:

.S. The effect of the "cancelling of the effects of the self inductance" is a
reactance thing, but it is not limited to AC excitement, the coil can be excited
with DC pulses at the correct frequency or alternating positive and negative
DC pulses (less than 50% duty or less than a Square wave AC). What the
patent does not relate to is Uninterrupted DC, uninterrupted DC after some
initial time only faces the DC resistance of the coil anyway, so no need for a
special coil, unless Pulsed DC is used or AC or alternating DC pulses.

If a coil is pulsed with DC pulses at a random frequency the coil will exhibit
reactance and the reactance can be cancelled if the excitement of the coil is
done at the correct frequency for the effect to manifest.

It's Tesla, 101. Using resonance effects.

When Farmhand says, "but it is not limited to AC excitement, the coil can be excited with DC pulses at the correct frequency" he is dead wrong.  For starters, "DC pulses" are actually AC from a circuit perspective.  You cannot equate an AC sine wave at a given frequency to a DC pulse train at the same frequency.  The coil will not react the same way to the two waveforms, even though they ostensibly are at the same frequency.  A square wave can be broken down into a series of separate frequencies, each one a sine wave.  The coil will react differently to each separate frequency and you get the final response from the coil by adding up all of the individual responses.  All of the sine waves with the exception of the fundamental frequency sine wave will result in some form of reactive response from the coil.

I just described the frequency-domain analysis.  The entire analysis for how the coil will react to a square wave pulse train can also be done in the time domain.

It turns out that "Tesla 101" is a little bit more complicated than some people think.  Note also that "Tesla 101" kind of has a feeling that somebody is trying to teach you something.   Please refer to my comments at the end of my previous posting about that issue.

MileHigh

[sparks]

   I would think that Tesla was having trouble with developing high voltage capacitors so he used the capacitance of the coil itself.  The coil is just a tank but the components are not discrete.  This would save on resistive and inductive losses in any shunts between discrete components.  If you take two sheets of aluminum with a seperator between same.  coil them up and drop them in some oil you have an oil filled capacitor.  You also have a bifilar wound coil.  You have mutual inductance as I would imagine electrons would be moving within the capacitor and give rise to magnetic field flux changes that would cause eddy currents in the foil.  All sorts of changes in the resonant frequency of the tank as the rlc values drift all over the place.  The necessity to monitor all the major components for values and adjust for changes in same.   Meanwhile the tesla bifilar wound tank suffered from few of these problems if any.