Monday, June 11, 2012

Moby Pulse Transformer

The astute observer of Friday's post will have noticed that while the magnetic forces in the loops are nicely contained (the hoop stress on the tubing walls is relatively minor) the forces on the collector plates are enormous and no features are depicted which control or contain those forces.

So yes: in real life, some big clamps of some sort will be required to keep the collector plates from flying apart on the first shot, turning our pretty transformer into something more closely resembling The Flying Spaghetti Monster.

I can think of at least two ways to accomplish this: C-shaped clamps disposed around the perimeter of the collector plates, located between tube insertions; and also, insulated bolts passed through holes in roughly the same location. Given that the output voltage will rise sharply (to a value dependent on the charge remaining in the capacitors and the energy still stored in the pulse transformer) when the armature leaves the rails, it would be prudent to insulate the bolts and plates to the charge voltage of the cap bank despite that the output side should never see more than 1/7 of the charge voltage, not considering ringing voltage reversal.

Free wheeling diodes capable of absorbing the high currents of voltage reversal with fast recovery times are available in industrial "hockey puck" packages, but their cost is high for an underfunded independent lab. I would not consider building a transformer like this unless I had some confidence of obtaining same first or soon after. One thing seems certain: we won't be purchasing them new.


PS: pictures accompanying my posts keep disappearing from older posts (despite that Google + Blogger claim there is no retention limit). I can't find some of the original images on my local computers now. Many of the images I uploaded to accompany those posts were uploaded away from home, and weren't saved on the phone, camera, or computer they were made with. So the older posts which discuss things like the fast micro-Marx generator probably aren't going to get their pictures restored. I mention this since I'm about to post about progress I've made this week on same, and I'd like to refer to those old posts with links, but thousands of words will have to suffice in place of illustrative images.

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