Bifilar pancake coil overunity experiment

[ayeaye]

No, i didn't say that current is the same everywhere inside a bifilar coil. Bifilar coil is not a single branch, it is two coupled windings connected with capacitance. In addition to capacitance, a current moving to the capacitance induces current in the other winding.

Tinman, your video can be easily explained. At higher frequencies the resistance of the capacitance decreases a lot, thus naturally most goes through the capacitance and not the other way. Some things were rather interesting, like the lightness of the led-s changed quite arbitrarily, i cannot quite explain that. This is not enough though to replace my interest in overunity.

[Void]

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.

Hi Brad. At frequencies in the high kHz and into the MHz range, that capacitive coupling current return
to the function generator ground can be quite significant. 100 pF at 1 MHz has an impedance of only around 1.6 K Ohms,
for example. If high voltages are being generated on the coil assembly, for example if one or both coils
is operating at resonance, a significant current (relatively speaking) can flow there. At resonance, single ended
coils can create a significant ground return current (significant relative to the input power level).

[ayeaye]

that capacitive coupling current return to the function generator ground can be quite significant.

This was essentially the first thing that i said after i saw the TinselKoala's video. There are two current paths, but he measured only one. Then Partzman said that this second return path is insignificant and i finally agreed, as this capacitance is sure much smaller than the capacitance in the bifilar coil. But to really find out, it can always be measured.

[F6FLT]

Hi Brad. At frequencies in the high kHz and into the MHz range, that capacitive coupling current return
to the function generator ground can be quite significant. 100 pF at 1 MHz has an impedance of only around 1.6 K Ohms,
for example. If high voltages are being generated on the coil assembly, for example if one or both coils
is operating at resonance, a significant current (relatively speaking) can flow there. At resonance, single ended
coils can create a significant ground return current (significant relative to the input power level).

It reminded me of a recurring problem for feeding the radio antennas, due to current on the shielding braid of the coaxial cables.
The solution, which could be applied to the cables of the FG and of the scope probes, is to wrap a few turns of the cables in ferrite toroid cores. The inductance created in this way has a high impedance that prevents or reduces ground currents.
But here there is a risk: aggravating the problem by creating resonance effects, especially if the impedance is not high enough! Only a test can tell us if it works.

[tinman]

Hi Brad. At frequencies in the high kHz and into the MHz range, that capacitive coupling current return
to the function generator ground can be quite significant. 100 pF at 1 MHz has an impedance of only around 1.6 K Ohms,
for example. If high voltages are being generated on the coil assembly, for example if one or both coils
is operating at resonance, a significant current (relatively speaking) can flow there. At resonance, single ended
coils can create a significant ground return current (significant relative to the input power level).

In my case,i dont think it would be of any value that would skew the measurements to much,as the max voltage across the coil was only about 13 volts peak.

Like all coils,i can make this one mostly inductive,mostly capacitive,and purely resistive,simply by changing the frequency.
See screen shots below.

Brad