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### Author Topic: The bifilar pancake coil at its resonant frequency  (Read 580495 times)

#### nelsonrochaa

• Hero Member
• Posts: 653
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1050 on: April 19, 2017, 05:07:17 PM »
@nelsonrochaa,

Thanks for the clarification. Consider this:

"Ørsted discovered the connection between magnetism and electric current when a magnetic field produced by a current-carrying copper bar deflected a magnetised needle during a lecture demonstration".

"In the CGS system, the unit of the H-field is the oersted and the unit of the B‑field is the gauss. In the SI system, the unit ampere per meter (A/m), which is equivalent to newton/weber, is used for the H‑field and the unit of tesla is used for the B‑field".

"H is measured in units of amperes per meter (symbol: A⋅m−1 or A/m) in the SI. B is measured in teslas (symbol: T)".

This is what you need to understand: The H field is an electrical equivalent and the B field a magnetic one.

Hi synchro1,
I just try show you that are some type of misunderstood between you and TK in relation to that theme of definition of what is  W and Wh
nothing more . what TK refers is what is agreed and write in actual conventional laws.

I know what is H field and a B field i have a meter do measure that values and you have right about that point .
Thanks
https://youtu.be/N3CjCNeH8rE?t=431

Nelson Rocha

#### synchro1

• Hero Member
• Posts: 4720
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1051 on: April 19, 2017, 05:08:07 PM »
gauss tesla (T) 0.0001 weber/sq.metre tesla (T) 1 ampere-hour coulomb (C) 3,600

#### synchro1

• Hero Member
• Posts: 4720
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1052 on: April 19, 2017, 05:23:27 PM »
1 Coulomb= 1 Gauss

1 Watt Hour= 1 Tesla.

A negative number multiplied by a positive integer can only yield numbers of a negative value. Like the negative one for exponent to the right and above the "H".

#### TinselKoala

• Hero Member
• Posts: 13958
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1053 on: April 19, 2017, 05:54:10 PM »
I was just interpreting what I think Nelson was saying. watt is a watt, and the difference between the Wh and W according to nelson they are the same just read over different periods of time. So it is like saying that the Kg is not the same as mg in a way.

No, the watt is a _rate_ and the watt-hour is a _quantity_. The watt is a rate of energy of one Joule per second passing a measurement point -- Like a mile per hour, it is a rate of "things" passing a measurement point in a unit of time. The watt-hour is a quantity, like miles is a quantity of distance, or what you read on the odometer, not the speedometer. Joules/second (watt) multiplied by time (seconds, hours whatever) gives you a quantity, a number of joules.

They are not the same thing by any means, and this is most certainly NOT like saying the Kg is not the same as the mg. It is like saying the mile per hour is not the same thing as the mile.

Quote
I suppose you would have to average them out. Id say as long as you have at least 1 full ac cycle that the average should equate to that fraction of an hour if it were measured in 1 sec. If in 1 sec you only measured 1/4 wave of the ac cycle, that would not give an accurate depiction of power used over a longer period of time. Thus the Wh?

Mags

Now you are getting all tangled up. Yes, to calculate or measure the number of Joules in a given time interval, you look at the power (watts, joules per second) and multiply that by the time involved (fractions of a second, days, weeks, whatever, reduced to seconds). Joules/second times seconds = joules. It's basic algebra!
The "Watt-hour"  means watts x time and results in an answer in joules. (Joules/second) x (seconds/minute) x (minutes/hour) = Joules !!  Algebra! The time units cancel and leave you with only joules, a _quantity_. Not a _rate_ like watt.

#### TinselKoala

• Hero Member
• Posts: 13958
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1054 on: April 19, 2017, 05:59:04 PM »
1 Coulomb= 1 Gauss

1 Watt Hour= 1 Tesla.

A negative number multiplied by a positive integer can only yield numbers of a negative value. Like the negative one for exponent to the right and above the "H".

Wrong three times in one little post.

1 coulomb is not one gauss -- that is why they have different names, BECAUSE THEY ARE NOT THE SAME THING. One watt-hour is not 1 tesla, and

a negative exponent means INVERSE, not "negative value".  X-1 equals 1/X, not some "negative value". Basic algebra !!

#### nelsonrochaa

• Hero Member
• Posts: 653
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1055 on: April 19, 2017, 06:03:27 PM »
No, the watt is a _rate_ and the watt-hour is a _quantity_. The watt is a rate of energy of one Joule per second passing a measurement point -- Like a mile per hour, it is a rate of "things" passing a measurement point in a unit of time. The watt-hour is a quantity, like miles is a quantity of distance, or what you read on the odometer, not the speedometer. Joules/second (watt) multiplied by time (seconds, hours whatever) gives you a quantity, a number of joules.

They are not the same thing by any means, and this is most certainly NOT like saying the Kg is not the same as the mg. It is like saying the mile per hour is not the same thing as the mile.

Now you are getting all tangled up. Yes, to calculate or measure the number of Joules in a given time interval, you look at the power (watts, joules per second) and multiply that by the time involved (fractions of a second, days, weeks, whatever, reduced to seconds). Joules/second times seconds = joules. It's basic algebra!
The "Watt-hour"  means watts x time and results in an answer in joules. (Joules/second) x (seconds/minute) x (minutes/hour) = Joules !!  Algebra! The time units cancel and leave you with only joules, a _quantity_. Not a _rate_ like watt.

Nice explanation
Thanks

#### TinselKoala

• Hero Member
• Posts: 13958
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1056 on: April 19, 2017, 06:11:56 PM »
Nelson, I'm glad we agree on this basic algebra.

And now we are beginning to see where synchro has gone off the rails. He clearly doesn't get that the Inverse is not the Negative. X-1 is equal to 1/X, not some negative value. And the H (scalar unit of induction) of the Henry is not the same as the  H (vector quantity)of the magnetizing field strength. He apparently has confused these two very different things in his mind, because of the use of the same letter for both. But the H of the field strength is a letter chosen at random by Lord Kelvin in 1850, and has nothing to do with the assignment of the name Henry and the letter H as abbreviation for the unit of inductance.

For Synchro: When letters are Bolded like that it is not done for emphasis. It is a common way to indicate that the quantity referred to is a _vector_ not a scalar. But I don't expect you to understand the difference, since the math is obviously over your head. You should however be capable of clearly understanding that the "H" of inductance is not the same thing as the "H" of magnetic field strength. Or am I giving you too much credit?

#### synchro1

• Hero Member
• Posts: 4720
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1057 on: April 19, 2017, 08:21:55 PM »
Wrong three times in one little post.

1 coulomb is not one gauss -- that is why they have different names, BECAUSE THEY ARE NOT THE SAME THING. One watt-hour is not 1 tesla, and

a negative exponent means INVERSE, not "negative value".  X-1 equals 1/X, not some "negative value". Basic algebra !!

@Tinselkoala,

Look again for the equal signs!

The negative Henry is the same as the Inverse Henry. Why don't you try and calm down?

#### synchro1

• Hero Member
• Posts: 4720
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1058 on: April 19, 2017, 08:33:31 PM »
@Tinselkoala,

You have been unflatterinly compared to "Thamsanqa Jantjie", Barack O'bama's fake deaf sign interrurpreter. When are you gonna knock the childlike antics off and settle down and act nice?

#### Magluvin

• Hero Member
• Posts: 5884
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1059 on: April 19, 2017, 09:05:37 PM »
I see knobody will answer my earlier questions so far, so Ill pose them again...

If we have a 100t tbf coil and we apply 100v dc, how long would it take for there to be 50v between all pairs of adjacent turns in the coil and what criteria do you consider determines the given answer, if it is ever given a shot.

Would one say that the 50v would be there between each turn only after the inductor has reached full current?

Mags

#### itsu

• Hero Member
• Posts: 1845
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1060 on: April 19, 2017, 11:12:00 PM »

Trying to merge the resonance frequencies of the TBP coil with that of the pickup coil is not that easy.

The screenshot (sweeping from 10KHz to 1MHz) shows the resonance frequency (the voltage this time) of the TBP coil in yellow around 300Khz.
The resonance frequency of the pickup coil in purple is around 500Khz and also picks up the 300Khz resonance frequency of the TBP coil.
Blue is the sweep signal from the FG.

I used a combination of fixed capacitors and variable capacitors to try to merge them, but they won't really, (guess i really have to look

Itsu

#### TinselKoala

• Hero Member
• Posts: 13958
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1061 on: April 19, 2017, 11:37:25 PM »
Itsu, It looks like you are getting very close to having the same resonant frequency on both "primary" and "secondary". I don't know what the result would be when you get them perfectly matched; in DRSSTCs it results in maximum power transfer between the coils, I think.

It would be very nice to be able to look at these things with a Spectrum Analyzer. Our scopes can probably do limited FFT analysis (mine can but it really sucks) that would be helpful but my scope's FFT function, even when working well,  is a poor substitute for a genuine Spectrum Analyzer. Maybe that's why really good SAs often cost more than a house and car put together.  I wonder if anyone posting experiments here has access to a proper SA.

Mags, why is this "unflattering comparison" photo, which is nothing more than TOS violation, personal attack and childish insult, allowed to remain in view?

#### gyulasun

• Hero Member
• Posts: 4117
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1062 on: April 19, 2017, 11:58:25 PM »

...
I used a combination of fixed capacitors and variable capacitors to try to merge them, but they won't really, (guess i really have to look

Itsu

Hi Itsu,

I think you would need to make the pancake's self resonant frequency a little bit tunable by connecting a max 100 pF variable cap in parallel with it first and then approach the pickup coil near to it with its own variable cap.
The detuning factor mutually affecting both coils resonances is the distance between them i.e. coupling between them. Any time you change the distance, you would have to retune both coils, this means you need coils to be tunable to both directions, up and down.   I do not think a  max 100  pF extra cap across the pancake would influence meaningfully any other properties of it other than its self resonant frequency.
The so called critical coupling would bring the most favorable response between the coils like in band pass filter cases.

Addition: I think any time there is a double peak created in the response then overcoupling is happening, this means you need to increase the distance between the two coils and retune their variable capacitors a little.

Gyula

#### skycollection 1

• Jr. Member
• Posts: 55
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1063 on: April 20, 2017, 02:43:03 AM »
In this video i am presenting a curious effect, the experiment consist in one big pancake coil connected to the circuit JL94 is driving a motor with a neoball inside of a plastic container, on top of the pancake coil i placed five PANCAKE COILS, (pickup coils) made of thin wire and all the pancake coils have a led bulb. The neoball turns at very high speed and when the magnet pases infront of the pickup coils "induces" a current that turn on all the bulb leds. This is the experiment....https://www.youtube.com/watch?v=hZaYpYOFvL4

#### MileHigh

• Hero Member
• Posts: 7600
##### Re: The bifilar pancake coil at its resonant frequency
« Reply #1064 on: April 20, 2017, 06:17:52 AM »
I see knobody will answer my earlier questions so far, so Ill pose them again...

If we have a 100t tbf coil and we apply 100v dc, how long would it take for there to be 50v between all pairs of adjacent turns in the coil and what criteria do you consider determines the given answer, if it is ever given a shot.

Would one say that the 50v would be there between each turn only after the inductor has reached full current?

Mags

Ignoring the speed of light, it's instantaneous.  However, just because there is 50 volts between two adjacent conductors and there is a measurable transient distributed capacitance between those two conductors does not mean that there is instantly an excess negative charge on one conductor and a lack of negative charge on the other conductor.  Any charge displacement to charge this transient capacitance would still have to flow in the form of current by snaking its way through the spiral conductors, and that means you encounter an inductance to overcome again and the energy to do that has to come from somewhere.  At the same time, the electric field is starting to push current through the coil in a conventional sense and slowly energizes the inductor.  It's very complicated with multiple things going on at the same time and in the realm of supercomputer simulation.

One part of the problem is that the bulk of the electric field flux is snaking its way through the coil and is pointed in the direction of the coil.  That electric field might manifest as a measurable potential on the surface of a conductor, but it is at right angles to any electric field that would be associated with the transient distributed inter-winding capacitance.

So we put a black box around the whole thing because it's too complicated and we just make empirical measurements of the signals that we can measure with our scope and apply our models on that.

I don't know why you want to believe that there is some "hidden magic trick" associated with a bifilar pancake coil.  What Tesla says in his patent is certainly about the reactance of the capacitance cancelling out the reactance of the inductance at resonance.  There are probably about 50 YouTube clips out there that explain this with phasor diagrams.  Phasor diagrams are more intuitive than hard mathematical analysis and you should check them out.