Here is a scope shot of me just hiting a micro switch that puts .02v across the coil then I open it. The scale is 20v so you wouldnt even see the input in the shot. Will set it up with a 1ohm to show input. But the first swing to the neg after releasing the switch, IS the largest swing of the oscillation. 

Will do more. Been real busy with work I have.

Mags

Seeing the 25mhz shown on the scope, knowing the coil calculated to about 180khz, I shifted the trace to the left and it is now consistently in the 230khz range. So the scope has more data to accurately represent the freq of the wave.

There is no spike like a single wire coil would show as we have seen them. Once the switch is open, the load is the scope. Not fg to pull down the coils oscillation once the input is disconnected, as I described earlier for this test. The scope probe may be altering the freq, but there is no ghz or even mhz quick spike like a normal coil typically shows.

Mags

Edit   The 180khz was actually calculated 85khz.  Not sure why the calculated and actual scope measurement is off by that much....But just wanted to correct that,,
http://overunity.com/17186/the-bifilar-pancake-coil-at-its-resonant-frequency/msg504458/#msg504458

Quote from: Magluvin on April 25, 2017, 05:48:34 PM
Seeing the 25mhz shown on the scope, knowing the coil calculated to about 180khz, I shifted the trace to the left and it is now consistently in the 230khz range. So the scope has more data to accurately represent the freq of the wave.

There is no spike like a single wire coil would show as we have seen them. Once the switch is open, the load is the scope. Not fg to pull down the coils oscillation once the input is disconnected, as I described earlier for this test. The scope probe may be altering the freq, but there is no ghz or even mhz quick spike like a normal coil typically shows.

Mags

I had found it strange that in brads scope shots the res freq of the single wire only seems about twice the freq of the bifi, and both shots on the same time scale. Maybe he can show us that in a vid to show whats going on better.

Mags

Typically we see field collapse spikes and they are pretty much prevalent.  So I changed up the voltage scale from 20v to 5v and lengthened the time scale to possibly see what is going on around the oscillations I had shown above. I also added the blue trace at 5v scale, but shifted the trace above the yel trace of the coil so both can be seen easier.

Gnd of both scope probes and neg of power supply(set for 4.2v) and one leg of the coil are all connected together. The blue trace is monitoring the power side of the micro switch, and the switch on sends current through the coil.

The first shot is switch off

The second shot is when switch is turned off from being on. I cannot switch the switch fast enough to capture on and off of the switch in one shot. So the coil is taking on full current before the switch is turned off...

We see that when the switch goes off, the yell trace goes low for a bit before the oscillation occurs.     What is that? Is that our spike dissipating current across the switch gap before the oscillation portion of the trace appears? Switch is open and only the scope across the coils leads.

More later...

Mags

Quote from: Magluvin on April 25, 2017, 01:06:03 PM
Hey brad

In your scope shots, it looks as if something is altering the ring of the oscillation when the trace gets near the neg peaks. If what you say and show is just that first pos 1% duty input(circled in blue), and after that it lets go, that first neg part of the cycle should be more than the peak of the pos portion of the cycle after that???

Its like there is a 13v zener diode pulling the bottom part of the trace (circled in red)to a lower neg peak than the pos peaks. Never have I experienced what you show there. I cannot see how your first neg peak is 13.6v and then it swings back up to 20v, and even 25v respectively.

Something is clamping down on your neg side of the wave.   Would be nice to see the setup you did that test with.

I cannot say your testing there is correct.  Dont you see it?

Mags

Easy to explain Mag's
As explained in post 1266--Quote: I have a diode on one of the input leads to each coil,so as we get a DC pulse going into the coils only.

The diode is clamping the bottom half of the wave 


Brad