The bifilar pancake coil at its resonant frequency

[Magluvin]

So in your first paragraph you are saying you get more induced into the secondary by not being at resonance with the input than if you are at resonance? That was the statement before especially with a freq of the sec res freq.


Mags

Hmm, well i just have to see for myself with my setup.  I just dont get that. 

Will see.

Mags

[TinselKoala]

So in your first paragraph you are saying you get more induced into the secondary by not being at resonance with the input than if you are at resonance? That was the statement before especially with a freq of the sec res freq.

Yes. Take a look again at the frequency scan attached below. You can see that the most voltage induced in the "secondary" happens at its own resonant frequency (great purple peaks at about 1.24 MHz) not at the resonant frequency of the TBF "primary" (the frequency of the "notch" in the CVR yellow trace at 273.2 kHz).

Are the bumps showing the 'off res freq' you are using?

Mags

That scopeshot was taken at the resonant frequency of the TBF "primary" (look at top right for the frequency counter measurement) which is where the CVR trace flatlines under no load condition. I think the bumps in the Blue trace are the "secondary" trying to resonate at its own frequency of about 1.24 MHz, a bit over 4 times the primary resonant frequency. Because of the way I had the LED oriented polarity wise, the LED is turning on at the flat bottom of the Blue trace and the top parts with the bumps are when the LED is reverse-biased and not lit. I think.

[TinselKoala]

I would just like to point out something here.

The Henry, denoted by H, is a scalar quantity and is the measure of inductance in the SI system.

On the other hand, H is a vector quantity that denotes the magnetizing field strength, and is not named after Joseph Henry and is not a measure of inductance. Its common units are Amperes/Meter. It is most certainly NOT equivalent to H, the Henry, the measure of inductance. The symbol "H" was assigned to this quantity in about 1850 by Lord Kelvin, who apparently picked the letters B and H at random.

Furthermore, there is a difference between the "negative" of a quantity and the "inverse" of a quantity.

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfield.html
https://en.wikipedia.org/wiki/Magnetic_field

[MileHigh]

To help understand this stuff, I am going to take a crack at a mechanical version of the parallel LC circuit acting as an infinite impedance at resonance.  However, next posting because this page has the wide sickness.

[MileHigh]

Are we on a new page?   Okay a fresh start on a new page.

We know the parallel LC resonator acts like an infinite impedance at resonance.  That means no power flows trough it, and therefore it is a no load device.

Imagine a large vertical spring on the floor with a heavy weight on top of it.   When you push down on the weight and let go the system resonates up and down at it's natural frequency.

Let's suppose the natural frequency is quite low, say two cycles per second.  Now imagine a person siting next to the resonating weight and spring system.  Imagine his coordination is very good and his hand is over the weight and moving up and down in perfect sync with the oscillating weight.

So, what do you see?  It _looks_ like the person is making the weight resonate up and down, but it's a fake-out.  The person is not applying any pressure on the weight at all, the system is self-resonating.  The person is not doing any work at all.

The person's oscillating arm is the function generator set on sine wave.  To be specific the _velocity_ of the person's hand is in the form of a sine wave which is like the voltage, and if he had to apply pressure to the weight, that would be the current.

Now, let's make one concession to the real world because we know that the resonant system will decay over time if you don't put some mechanical power into it.  Let's ignore air friction and focus on the spring as a lossy spring.  The spring will heat up just like the proverbial bending of the coat hanger and that friction will dampen the resonant oscillation.

So in the "real world" as the person's hand follows the up and down sine wave motion of the weight, every now and then he applies just the tiniest amount of pressure to the weight to ensure that the resonance remains at the same amplitude.

So when the person puts just a little touch of mechanical power in the resonating spring and weight system to keep the amplitude stable and compensate for the resistive looses in the spring, likewise the function generator puts a little touch of electrical power into the parallel LC resonator to compensate for the resistive losses in the inductor.

That gives you a basic idea of what is talking place.  However, it really needs work to get it 100% bang on and I am not going there.  Likewise I am not going to delve into a mechanical equivalent of a series LC resonator.

The big takeaway is this "no power flow/no load" condition all only works at the resonant frequency where the excitation (moving hand) is a perfect sine wave.  If you deviate from that set of conditions it simply doesn't work.