I took my toroid, with the bucking coil on it, and measured the impedance of both counterwound coils. they were 0,30mH and than I measured the primary of my double pancake coil, it was also 0,30mH
This is perfect for transferring bemf voltage spikes from the bucking coils into the bifilar coils.
On the toroid there is a primary wound (that could be made bifilar) that is being pulsed bu my igbt. This creates a magnetic field in the toroid, and the b emf is captured by the bucking coil. The bucking coil is grounded in its center tap.
Both ends of the bucking coil produce b emf impulse currents. of several hundred volts, equal polarity.
But it needs to be 50 khz to 100 khz because at higher frequencies it start ringin.
The b emf is fed into a bifilar coil, that makes a center bifilar coil resonate.
So the b emf, from a 12V pulsed toroid is used to get a bifilar coil into resonance.
The resonant bifilar coil, needed to tune down its resonant frequency. This I did by adding a capacitor in parallel over the resonant coil.
This, became a problem. because the resonant Sine voltage rise(from the few hundred volts b emf) is potentialy several thousand volts in amplitude.
I didnt realise this at first. So I just used 2 caps in parallel to get 7nF. one of the caps had a 100V rating. The sine showed a rappid growing but in a strange way. then I noticed a strange smell, and I saw the 100V rated capacitor melt away :cool:
So I cooled down, and got 10nF 630V rating capacitors, and dialed down the resonant frequency to around 80khz. And it became hot.
fast. So I stopped again. (not realising the resonant voltage rise had a potential of much more than the 630V).
To protect the capacitor, I added a 330 ohm 1/4W resistor. The sine now was lower (i remember something like 35V). But still the resistor became very hot!!!
To me this indicates some power. But at the same time, the power is dependant on how high the resonant voltage sine rise gets.
more volts is more power...
I also tried, a 8V lightbulb, across the capacitor, but it killed the resonance, the voltage kept low, and the power was gone, the lamp showed a little glow. I reproduced the glow with a dc power source and it resembeld 0,2W or something low like that.
So this gave 2 problems, and at the same time a very exciting result.
I could use very low power conduming b emf, to create a very high voltage resonant sine wave.
But at the same time. I didnt have the right capacitor to tune the resonant coil down...
To fix this, maybe I could use several larger capacitance in series, so it will take the voltage better. best would be a 10nF high voltage capacitor... that i dont have right now.
In the past I found out it was a factor 70, so 70x 500V (bemf) would produce a 35000V sine wave potentialy...
ok so thats why the caps were melting away...