Hi,
I'm new on this forum and just read through this topic. But some questions/comments arrived:
@Dynodon:
The core was two flat U cores about an 1/8 inch thick and about 1/2 wide
Jesus, was the core area really that small on this 5-Coil-VIC? Is that a screw in between the 2 choke coils on the pic, or is this the core? If it's the core, then from the picture it looks definitely gapped. This would be for me actually the only explanation, how a core with such a small core area could have been used without being saturated. Although if only a small current is flowing, with that many windings (from the pic and AWG size I would guess about 2'000 per bobbin), it would certainly saturate any ungapped Iron-powder or ferrite core. I would even have doubts if a steel core could handle it with such a small core area.
If it is an ungapped core, then the only conclusion I could draw is, that he intentionally let the core go into saturation.
Alan,you can use a voltage divider.Get 10 each 1megaohm resistors and hook them up in series.Hook one end to the cell positive and the other end to ground.Then hook the scope probe between the 9th and 10th resistor.That would be closer to the ground end of the resistor dividers.This will give you a divide by 10 output to the scope.With a probe set on 10x and this divider,you'll get 100:1 ratio.
Just a little correction. I think you accidently made here a mistake by saying only 1MOhm instead of 10, for at the beginning of the thread you explained it correctly. To get a 100:1 with a 10:1 probe you need 9x10MOhm resistors. That means actually a resistance of 90MOhms. Your 10:1 probe has internally a 9MOhm resistor. The oscilloscope has a 1Mohm input resistance. So you will now have in total 90MOhm from your resistors+9Mohm from your probe+1Mohm from the oscilloscope=Total of 100MOhm. As the scope has a 1MOhm input, it will see only 1/100 of the total voltage.
So again in a short version: You need to place 90MOhm (eg. 9pcs of 10MOhm resistors) in between your 10xprobe and the cell to measure at 100:1. Voilà!
Did you actually really exactly look, how the coils were interconnected, or is this just a guess. As I understand you say, they were all connected in series with the WFC in between all in the same orientation. This means: If the primary gets current, then: The pos side of the secondary goes to the diode. The pos side of the first choke coil goes to the WFC. The pos side of the second choke coil is again at the secondary.
Additional question, which I think could be important. Did you see, if he electrically isolated the circuit, or was it grounded. Was the neg side of the secondary anywhere connected except the second choke coil, or was there any other ground connection (E.g. was the diode in the 5-coil-VIC mounted with isolation)?
Additional question: Somewhere here in the forum you state, that the "8XA-Circuit" wasn't a resonance circuit. How did you get to this conclusion?
I don't want to offend you, but I think it actually is. If you simply connect and drive it in the way Stan did, you will clearly see, that at a certain frequency you will get a resonance.
(I attached a small pic of my scope which shows the resonance condition. Unfortunately I could only drive the circuit with 20Volts, as my frequency generator surely cannot output more. I also only made very few windings, therefore the resonance frequency is a bit high (25 KHz), but I think the basic principle remains the same.
If one does look at how he connected the choke coils in this "8XA-Circuit", it is obvious, that if he really connected them like that, then they surely do not limit current in any way, as they cancel each others field out and are only seen as a resistance by the input voltage. But due to the capacitance in the system (and I don't mean the WFC capacitance, as this capacitance is at least for this circuit almost completely neglectable), the system is able to start to resonate and the voltage of the coils rise.
(http://img198.imageshack.us/img198/5135/yellowonwfcbluefgsignal.gif)
Blue: Input Signal after the Diode
Yellow: Signal on WFC (first choke coil side)
Red: Voltage over first choke coil
If this is really how this "8XA-Circuit" worked. Then it would make sense, that he introduced the primary/secondary (in a forward converter usage) as a replacement for the direct connection of the input voltage. But if the 5-Coil-VIC really would also have worked on the same basic principle, then the choke coils would have been wired differently (namely the same way, as in the "8XA-Circuit"). Therefore my above question about the wiring and orientation. If you say, that the choke coils in the VIC you saw were definitely (100% sure) not connected like that (same polarity to WFC), then that's OK, but I just wanted to be sure about that.
I would be really grateful if you could shed some light on these points, as you are the only one I know, who actually really saw Stan's originals.
I would go for what stan said, oriented grain electrical steel laminations. This is made to work at high frequencies.
Just to mention: The most important factor, when it goes about laminated steel cores and frequency is lamination thickness. If you go by the frequencies here used, i would say, the laminations should be <= 0.25mm. And to get cores with such thin laminations is not that easy. Audio-Transformers usually have them, as they also operate at these frequencies.
