"Killer" Screen Driven Push-Pull Amp Initial Queries

[kenpeter]

What?

[jkeny]

What I mean is: why do we need the C-shape at all - just to thread the wire through the centre of the toroid?

So my idea was just use a wheel as you suggested with the wire around the rim and going through the centre of the toroid which is pulled away from the wheel by a spring for tensioning.

So just the same as the patent but the toroid is not in the any C-slot, it is pulled away from the wheel which contains the wire on it's rim and it stretches to the toroid through it's centre!

[kenpeter]

I repeat... What?

How do you pull the toroid away from the bobbin (rim or C) while
it is still held captive by the pre-loaded windings? I just don't see
how you intend to pull anything away untill all the windings have
been transferred.

[jkeny]

You start with the toroid pulled away from the bobbin (wheel) and thread the wire by hand through the toroid & around the wheel rim as per Don's description.

Basically, everything is done the same as per Don's description except the toroid is held away from the bobbin by a tensioning spring.

The original C-shaped sausage belt is conceptually the same as a circle!

[smoking-amp]

Hmmmm.... I think I see what jkeny is trying to do, but as kenpeter said: what? The pre-wound wire in either scheme is a big circle passing thru the core. I don't see how you can move it away from the core dynamically for tensioning. You could move the C drive away, but the wire bundle thru the core would then have to dynamically deform every rotation. Not too good.

Let me mention a Japanese patent. They wanted a scheme to wind tiny tape head cores. Obviously it had to be shuttleless. Instead of winding the wire on something thru the core, they just spread the wire out in a long trough with air flow thru it, like the way the old 9 track computer tape columns used for tensioning the tape. The wire end was then guided around thru the core opening by air jets then back into the trough. One turn at a time getting wound on the core. I don't think this would allow accurate positioning of the wires on a core without some very fancy mechanical contraption though.

I think the Potthoff scheme is reasonably workable. Maybe could use velvet against the teflon C side for the wire accumulator, for smooth tension control.

Another concern I have for the Potthoff scheme is how the wire gets back into the accumulator slot after the spillover point passes thru the core cutout section in the C. It has to get back up on the rounded Teflon C edge again. This seems tricky to me. Likely requires some tapered section of the rounded C edge to lift it back up. But the wire could just as easily decide to get snagged in the cog belt to Teflon C edge clearance. (ie, between the belt and the Teflon edge)

Don

[smoking-amp]

The Holy Smoking Toroid Winder

Just for laughs, here's an idea:

We start with a very long U shaped pipe with a narrow slot cut in the inside side along the length (ie, inside side of the U) Air is blown into the pipe from one end. Very small primary wire is then fed into the air inlet end of the U tube and blown down and around the U until it emerges from the other end. Air jets then blow this wire end thru the toroid and back into the inlet end of the U tube.

As the wire sails around thru the toroid it gets shorter in the U tube and pulls across thru the slot in the U (ie, takes a shortcut short of the U bottom end eventually short cutting the whole U and pulling up tight on the toroid). Since each turn wound on the toroid will then shorten the remaining wire, we move the core gradually down the U tube with each turn so that it will blow the wire down around the U and back to where the toroid is. So the wire now enters and leaves the U tube thru the slots near the toroid and this point progressively moves down toward the U end as the wire is used up. Each turn still shortcuts across the U thru the slots as it pulls up tight. (shortcutting starts at the U bottom end each time)

The tube cross section would need to be a circle with a V extension on the side protruding out to the slot, so that the wire can easily find its way to the slot as it pulls tight. Well, actually, only the end of the U needs this special shape.

Of course, with 1000s of turns, I would hesitate to calculate the length of custom pipe needed. And the amount of air flow required.

Don

[wrenchone]

The latest stuff about toroidal XFMRs has gone far beyond the initial intent of the thread, and shoud be moved to a separate thread, where folks in the future might easily be able to find it and benefit from it.

[wrenchone]

This idea hasn't died - its percolating quietly in the background. I've decided for the time being on Edcor output transformers, as they are cheapest and I like the looks. If anyone has had experience with the Edcor 5k, 100W push-pull transformers, please speak up.I haven't bought any output iron yet, and won't for a while.
Private communications have given me some options to try to boost HF bandwidth. These will be held in reserve until I see how the simplest version of this amp performs. The screens of the output tubes will be driven with source followers, so there will be plenty of current available for the screen and for Mr. Miller.

I've been collecting 35LR6s to see who is best in terms of husky plate construction. Mum's the word on my favorites until I get my share....

[Jeb-D.]

I have been very happy with Edcor. Everything I've got from them seem overbuilt (in a good way). I don't think you will be disappointed.

[wrenchone]

I've bought from Edcor before - I wanted specific poop on the 5k, 100W transformer.