Bifilar pancake coil overunity experiment

[gyulasun]

Hi Brad,
Very likely there is a parallel resonance developing from the two windings and their dirstributed capacitance at around 11 MHz and the loaded Q of this 'LC tank' can remain high enough to 'produce' the measured 2.25 V across R1. So the input current to this parallel 'LC tank' should be Q times less via the csr so this smaller current can only cause a small voltage drop across the 2 Ohm csr.  Perhaps doing a differencial voltage drop measurement with two probe tips across the CSR can show the 5 to 10 mV voltage drop that cannot readily be seen in the present 2 V/DIV settings.

Gyula

[F6FLT]

...
At a certain frequency,I now have 0 volts across my CSR (R2)  , but i have 2.25 volts across the load resistor (R1)
...

We are poorly equipped for accurate high-frequency measurements.  Radio amateurs never use scopes for RF power measurements. Just the capacity of the probe disturbs the signal or the magnetic flux through the loop between the tip of the probe and its ground wire (even when the tip is connected to the end of the ground wire, you can measure a significant signal at all), and the cable shielding may be insufficient.

Maybe we should go back to some very basic things. When I needed to measure high frequency voltages in the past, I placed a diode+cap circuit in series on the load and measured the DC voltage across the capacitor.

For example, here, to measure CH2, the diode would have to be connected to CH2 and in series the capacitor C to ground. A germanium or Schottky diode must be used to reduce the voltage drop (0.2->0.3 v vs 0.6 for Si), and the capacitor will be of the order of 0.47µF non-polarized (non-critical value).
The capacitor will charge to the max sinusoidal voltage minus 0.25v. If Vmax is measured, the rms voltage will be Vrms = (Vmax+0.25)/√2. The same method can be used for the 3 points of measurements with the same Diode+C circuit (just use a flying wire soldered to the diode, and use it as a probe). The setup will be much less disturbed than with a scope probe, the parasitic capacitance of the diode being low and the current taken very low because when the capacitor is charged, almost no current is drawn by the diode. And measuring a DC voltage avoids frequency sensitivity dependence, and avoids the long wires of a probe which, although coaxial, are often "porous" to radiation.

The disadvantage is that the measurable voltages must be higher than the diode voltage bias.

[Void]

Void

I see no problem here.
Ch1 is measuring the voltage across the function generator.
CH2 is also measuring the voltage across the function generator,minus the voltage drop across a pure resistance(the CSR).
All ground leads are connected at one point,and that is at the ground lead of the function generator.

As i said,i see no problem with the circuit provided,or any of the measuring points.

Hi Brad. Just because someone doesn't see something, it doesn't mean it is necessarily correct.
I have suggested how you can test it using a regular transformer to see whether placing the CSR there
with the probe grounds placed where they are gives correct results or not. I am tied up with other
things so can't demonstrate it right now. When Itsu uses his current probe at that same point
it does not have the same problem however, as it is measuring the actual current waveform as it actually is.
Itsu using his current probe at the same location should be showing a more correct phase angle measurement.

Placing the CSR and probe grounds where you have them means you are trying to measure the current phase angle
across both the function generator and the CSR. This is ok for measuring voltages if you take the difference,
but it will be incorrect for measuring the phase angle between the voltage waveform and the current waveform.
Think about it. How can you correctly measure the current phase angle when you are measuring across both the
function generator and CSR at the same time?

I wish a Merry Christmas to everyone!

[ayeaye]

It turned out

Yes it turned out without experimenting or anything, it's quite interesting how the things turn out.

[tinman]

 author=F6FLT link=topic=17861.msg528771#msg528771 date=1545760211]

We are poorly equipped for accurate high-frequency measurements.

I would have thought that a 50MHz scope and probes was well within it's limits at 12MHz.

Maybe we should go back to some very basic things. When I needed to measure high frequency voltages in the past, I placed a diode+cap circuit in series on the load and measured the DC voltage across the capacitor.

Yes,i have also done this in the past,and will give it another shot.

But i agree with void--the way the circuit is,and where the scope probes are placed,we will not see the voltage/current phase offset--the two will always be in phase regardless.