Self running coil?

[gotoluc]

Hi Luc,

Could you make a test for me?  It would be this:

Just connect a 533pF capacitor (ceramic or mica or any normal capacitor) in parallel with the toroidal coil that has your split wound coil and also the magnet attached and please repeat the same test you showed in your present video but this time you would find resonance also at around 6kHz like in case of the other normally wound coil that has no magnet attached.

I would be interested to know the current value.  No need for making a video on it, just tell.   (I know 533pF cannot be had, maybe you could combine some smaller standard values in parallel to make up for it, no problem if you approach it only to +/- 10pF precision, maybe you have a variable capacitor then it would be good to use, together with the C meter first.)

Thanks,  Gyula

EDIT: one more thing: would you measure the DC resistances of the two toroidal coils you have used? thanks.

Hi Gyula,

I just completed your test.

I used a 390pf and a 120pf in parallel and it gave me exactly 533pf   well, that is what my meter says anyways.

The current is not returning but very close   it is at 0.8uA

I have found it to be more efficient when not using capacitors to lower frequency. So this maybe the difference of without the caps in parallel with the coil is sending back 3uA

I took a scope shot of it also so you can see the wave forms and data.

I hope this you

Luc

ADDED

I was actually able to drop it some more by removing the scope probes. I have found that they interfere a little. The lowest I could get it down to is 0.2uA  Good thing I could hear the coils 6KHz

[gotoluc]

Gyula,

I decided to reconnect the no magnet toroid and re-tune it to the best of my ability to use the less current but also keeping the RMS value to the same as the magnet dual coil toroid test above (see scope shot below to compare both). I was able to get the no magnet single coil toroid down to 1.8uA compared to the magnet one above at 0.8uA

There is a small gain using the magnet but by keeping the inductance on the dual coil to the same as the single coil we don't have much much of the PM flux participating in it. Just one 1/2" x 1/8" plus two paper spacers. We need to consider this also.

I think it's time to wind a new toroid. I hate winding toroids

A user at the Energetic forum asked me if we had 4 coil sections instead of 2 would the inductance be more than 2 coil sections?  I said I don't know   what do you think

Thanks for your help

Luc

[NextGen67]

Hi everyone,

Since I changed my cap bank meter to a 10 Ohm instead of the 1 Ohm resistor to get more resolution on my meter I'm getting confused. <...>

It will take me some time to adjust using the 10 Ohm but it's worth it as it gives me much better resolution. Maybe I should even go to 100 Ohms!... but I don't have a 1%

I also decided to retest the 20KHz self pulse test I posted on page 26 first post. The more accurate reading is 17.5uA and not 14uA
<...>

Luc

I don't know if the meter became more accurate?

The difference between 17.5uA and 14uA [being 3.5uA], might be introduced by the 10 Ohm resistor itself? As this resistor is part of the whole circuit, and also uses some energy.

--
NextGen67

[NextGen67]

NextGen,

Sorry I do not fully get you, something is foggy: what kind of formula do you think of?
And for the IRF640, which capacitance is the 1578.54pF ? Ciss, Cgs, Coss? How did you get it?

By the way, would it not be better to wait for the person referred to by Luc what he comes up with first?

Gyula

Hi Gyula,

Well, the standard formula to calculate L,C or F cannot predict C on it's own.

My point is, that it must be somehow possible to get a quite close estimation by using data from the data sheet of the particular mosfet, to -on beforehand- determine what it's 'final' Capacitance 'result' would be when being plugged into Luc's circuit.

The 1578.54 pF is derived from the 5 to 50 Khz scope shots Luc provided... If you put his main coil mH and the belonging frequency for each scope shot in the online LC calculator, you will see that all scope shot frequency's/mH's come to between 1533 and 1580 pF

So if we can get a good estimation of this C value,  we might in the first place get a better understanding between Ciss, Coss, Crss, Rds(on), Vgs(th) and Vgs, wrt the circuit, and by such we would be able to find the 'perfecft' match mosfet.

In the 2nd place, it *might* be such, that for optimizing the circuit to 100 percent [well as close to it as possible], we need to know the mosfets C value to begin with, meaning the circuit would be fine tune designed around that value.

My values by the way might differ slightly from online type calculators, as I do calculations the old fashion way .

--
NextGen67

[forest]

you have to change slightly duty cycle of square wave to get breaks at peaks of sinus