The bifilar pancake coil at its resonant frequency

[tinman]

 author=Magluvin link=topic=17186.msg505484#msg505484 date=1493144011]

Well thats interesting. Your single wire coil seems to outperform inducting the square coil.  For sake of argument, those screw terminals in the middle of the coils look to be different sizes and could be acting as cores in what is suppose to be an air core test. Just thinking. The one in the single is larger.

The chocky blocks are marine grade-all stainless steel.
I used them for the very reasons you mentioned.

Did you record the freq for each result? Or were both coils results happening at the same freq?

52.8KHz for both coil's
This is the frequency maximum amplitude was reached across the 680 ohm resistor on the pickup coil,for both pancake coils.

This would be a first for me that a supposed identical single wire coil actually outperforms a bifi of the same. If the resistance and inductance are the same, where do you suspect the loss to be credited to?

I suspect the loss is because of the very thing most here seem to think is a wonderful thing--that being the larger value of voltage between turns in the BPC.
Think about it. Both coils have the same surface to surface area,so we could expect that the overall capacitance of the coils to be the same value.
Difference is,with the single wound coil we are trying to charge each set of plates(parallel windings) to a small value of say 1.2 volt's,and with the BPC,we are trying to charge each set of plates to say 50 volts.
So,instead of most of the input energy going into the primary coil being used to induce the secondary coil,some of that available energy is going into charging the self capacitance of the coil,and with the BPC,that charge is a lot higher than that of the single wound coil.

TK done a video a couple of days ago,that also showed that the single wound pancake coil had a slightly stronger magnetic field.


Brad

[tinman]

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

That is the coils self capacitance being discharged.
And it is also the same as what i get for the first negative pulse.




Brad

[tinman]

 author=Magluvin link=topic=17186.msg505364#msg505364 date=1493033673]

Hey brad

Thats not the brad I thought I knew. The Brad that comes up with out of the box ideas on things that captures everyones attn. Where did ya go?  Miss ya.

Took me a while to find this post lol,but i knew it was there some where.

Ok Mag;s
I didnt let you down--i kept on hunting-->and i found it.

Be prepared to be blown away--even MH will have to rethink how inductors/coils work--well in the case of the BPC anyway.
Were about to gain a new understanding about the BPC,that i have not seen in any other coil.

But first
I give all the Tesla BPC guru's a chance to put forth any differences they have found with the BPC,to that of any other coil.

The way this is going to happen.
First step-i will shoot a video.
I will then show TK the video,and ask him to confirm my findings.

Once that is done,i will post the video here,and show you what i have found.
I also believe i have an answer as to why this is happening--but we'll leave that till later.

Until then.


Brad

[hoptoad]

snip...
Be prepared to be blown away--even MH will have to rethink how inductors/coils work--well in the case of the BPC anyway.
Were about to gain a new understanding about the BPC,that i have not seen in any other coil.
snip..

This toad is curious. Hope you found a worm, better still, a can of worms. I love worms.   
Cheers

[Magluvin]

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

Ok.  Well then the collapse neg swing should not be 13.6 for each as you claimed they were the same for each coil. Just clarifying that, as one coil was higher in up swing than the other, it did not make sense that the first bottom swings were identical and limited. So the diodes removed should change those readings, even the up swings for each of 20v and 25v as the initial down swings were burning up the in the diodes before the up swings.

So the inductive kickback is not the same for each coil as you stated and should be corrected as the diode was limiting it to be the same for each.

Mags