The bifilar pancake coil at its resonant frequency

[Vortex1]

My response video to Russ's response video.


https://www.youtube.com/watch?v=nHqs72bYyUw

Good job on the response to response video Brad.

More informative, and tells the truth of the matter. 

Keep up the good work!

Regards

P.S. might be interesting to put some tiny matched incandescent lamps in place of the 100 ohm resistors and drive the circuit harder....just for fun. 

That would give you an  eyeball current and power indication / balance in the loop.
Three would be even better, one on the right, the middle and the left. Just don't connect the scope or the balance will be upset.

[tinman]

Good job on the response to response video Brad.

More informative, and tells the truth of the matter. 

Keep up the good work!

Regards

P.S. might be interesting to put some tiny matched incandescent lamps in place of the 100 ohm resistors and drive the circuit harder....just for fun. 

That would give you an  eyeball current and power indication / balance in the loop.
Three would be even better, one on the right, the middle and the left. Just don't connect the scope or the balance will be upset.

Hi Vortex

I tried the smallest grain of wheat bulbs i have,and the SG just dose not have the power to light them up.


Brad

[tinman]

Below are the scope shots with associated scope placings as requested by TK,with the widened time scale.
I have also included the math trace for each,which is showing the result of V x I.

Anyone seeing a pattern forming here with all these tests ?


Brad

[TinselKoala]

Those tiny incandescent lamps are called "grain of wheat" bulbs and I am happy--- and rather astonished--- to see that they are still available in this day of the ubiquitous LED.

http://www.ebay.com/sch/?_nkw=grain%20of%20wheat%20lamps

[Magluvin]

By using a TBF coil with more turns he could have brought the frequency range of interest down to within the range of his current probes. And as we know, as I have demonstrated,  you don't need a pancake coil to show the effect, it works just fine with TBF solenoid coils too, which are _much_ easier to wind. And it even works with monofilar coils, but less strongly since they have less distributed capacitance.

Russ demonstrated the phase shift which we all know is there and which will occur in _any_ inductive coil whether flat, solenoidal, Tesla bifilar, or monofilar wound.
It's too bad he didn't also demonstrate the power analysis software of his scope. He probably needed the current probes active and deskewed to be able to do that.

So the appropriate way to test this circuit is to measure the Vdrop across each resistor separately, without making groundloops by misconnecting the voltage probe references. In fact I do this using the same scope channel and probe, by moving the probe from resistor to resistor, so as to be absolutely sure not to introduce ground loops (and also I know for a fact that my FG's outputs are isolated from ground; is Russ's FG also isolated in this way? Many aren't.) This will give the actual power dissipated in the resistors, and no correction for phase need be applied in this purely resistive case.  Then one measures the power relationships in the inductive portions separately, and using the Phase Shift between voltage and current in the inductors themselves, one can calculate the Real power, Reactive Power, and Apparent Power in those mostly non-dissipative inductors. Here is where Russ's Power Analysis software in his scope would come in handy.

Hey T and Brad

So when measuring R1 we can calculate the input power as it is showing input currents whether they are the result of the interaction with the coils and the other resistor or not. Then we have R2 showing more dissipated power than what we see on the input. Whether we have looked at the coils independently or not, with just the 2 resistors we are seeing something more than in on R2.  Is that correct?

Wondering something. I know its probably silly, but what if we took out the 100ohm R1 and put a 50ohm at each end instead.  I dont know why yet exactly but when we have the differences in coil voltages, rms, pp, there seems to be an off balance set in.  Like if we did the 50 on each end, would we have balance? Possibly the 1 winding compared to the other may have differences, but,  anyway.  Cool stuff.

Mags