Bifilar pancake coil overunity experiment

[ayeaye]

Swapping it out for a 1/2 watt carbon resistor made all the magical OU disappear 

Ok, thank you for finding it out. Means that we should go back to the beginning? As these circuits with a weird way of using bifilar coil, after all appeared to be no way to go. You got overunity results at very high frequencies, yes 13 MHz, inductive resistors that supposed to be non-inductive, may explain this.

Void, you should somewhat more understand the basics. The figures below are made with geda, which is a spice simulator like LTspice. See that the current has always the same phase, no matter where in the circuit. In spite that there is both a capacitor and an inductor in the circuit. It has the same value everywhere too, but i made one resistor two times greater than the other, so that both traces can be seen. See that the current somewhat leads the voltage, because in spite of the inductor, the circuit is mostly capacitive. It is true when the circuit is all connected in series (when all is one loop). It is not true about the current in parts connected in parallel in some components of the circuit.

The direction of voltages below is correct in accordance with the kirchoff's law. One may ask why is the voltage on the voltage source inverted. It is, as the movement of the assumed positive particles is from + to - in the voltage source, when the power is consumed. But the voltage on the rest of the circuit is not inverted, and this is what one should use, like when calculating power.

Indeed try to measure some simple circuit, like that on the figure below, with only a capacitor and a simple coil, with the same components that you use and the same ways of measurement. Then simulate it in LTspice and see how much it differs. That way you will see at once when some resistors are inductive or anything else is not how it supposed to be.

[tinman]

Hi Brad.

What was the frequency of operation there? Was the scope set to 50nS per division? 13 MHz approx. ? ? ?
... or am I reading that wrong? Are you using non-inductive resistors for the CSR and load resistor?
It is looking like your load resistor R2 may actually be inductive, and if that is the case that could cause
the current reading across it to read considerably higher than the true resistive load current.

It is possible that Vin and Iin could be close to being in phase if the pancake coils are being driven
at a frequency that is close to a resonance point for them.

Also, see the attached picture of your latest test setup with some additions from me.
I have indicated three different currents: I1, I2, and I due to capacitive coupling back to the function
generator ground. All three of these currents are not equal in both magnitude and phase angle! These
are three different currents. The current returning to the function generator via capacitive coupling bypasses
the CSR R1. Your measurement of the input current therefore will not be accurate IMO.

It is for this reason that I said that I think using a current probe at the 'positive' output wire
of the function generator is probably the best representation of the input current for this type of setup,
assuming the current probe is reading reasonably accurately for both magnitude and phase angle.  However,
due to the complexities in making accurate measurements in this type of setup, I personally would still
not have a high degree of confidence in the accuracy of those measurements even when using the current probe.
That is just me however.

Yes,like i posted in reply 278,when looking at the other circuit.

I do mostly agree with what you say,although there are some points that need more study --to me anyway.

Brad

[ayeaye]

Tinman, why is that capacitor drawn there in your circuit? The equivalent circuit should be something like that on the figure below, with no capacitance where you drew it. Or is it a yet another modification of the circuit?

That capacitance sure adds capacitance to the circuit loop. The only place in that circuit where the current may be different in value or in phase, is in the resistor R1, because it is parallel to the secondary winding of the bifilar coil. In all the rest of the circuit the current is everywhere the same.

[tinman]

Tinman, why is that capacitor drawn there in your circuit? The equivalent circuit should be something like that on the figure below, with no capacitance where you drew it. Or is it a yet another modification of the circuit?

That capacitance sure adds capacitance to the circuit loop. The only place in that circuit where the current may be different in value or in phase, is in the resistor R1, because it is parallel to the secondary winding of the bifilar coil. In all the rest of the circuit the current is everywhere the same.

It is to indicate the small amount of stray capacitance that creates a small current loop,such as void was talking about in post 360.


Brad

[tinman]

In all the rest of the circuit the current is everywhere the same.

No
When dealing with these BIFI pancake coils,the current is different throughout the bifi coil windings,and the value at each point depends on frequency.
It will only be the same at the start and end of the coils.

Watch this video,and see what you think.

https://www.youtube.com/watch?v=2JK7PYBdMUI


Brad