Never imagined this to be skull-worthy, so I guess I'd better explain:
I can't take credit for this idea...
@Hacker404's #Full Size Image Gallery and corresponding Thumbnails Gallery stumped me for quite some time, but I think @Hacker404's idea (if I understand it correctly) has basically been reimplemented here for my own purposes.
But, I won't explain what this idea is, here... it's a (really simple) riddle, or something, that you too could find useful.
It's all about the pictures!
(Looking back, this coulda easily been implemented in a "Page" just as easily, and wouldn't hog-up my project-space... but there's some good comments here, so I'm not gonna change it any time soon)
Still trying to figure out what would happen with the AC-driven unipolar stepper arrangement of the last log... came up with this plausible solenoid-synchro using permanent magnets:
If this works as I imagine, it's very different from merely connecting the two solenoids in parallel, and not connecting an external power source.
In That case, an external force moving the 'sensor' solenoid's magnet only induces a current when the magnet is moved. When stationary, no current flows, thus, it's entirely possible to have the two magnets in entirely different starting positions.
Also, the current induced by a small/slow movement would be far too weak to overcome external forces like friction and inertia.
With the AC-driven arrangement, the frequency must be much higher than can actually cause motion... But, if it works as I imagine, the effect of a stationary permanent magnet on a single winding should be a net DC bias.
Connecting two windings in parallel, then, would tend to cause both magnets to position themselves similarly so the DC bias on each path matches.
This, then, would synchronise the two magnets even if they have differing starting-positions.
Lots of weird effects to consider: eddy currents, ferrous vs air-core, saturation... Then some other interesting ponderances: A larger AC voltage would give a larger DC offset... intriguing. And what if the two coils were in series, instead? (More like the stepper-scenario of the last post... and more like the synchro diagram from Al W.... and making me ponder Y vs Delta configurations for synchros).
Surely not at all efficient, but something, anyhow.
Some reading material with basically the conclusion that it depends heavily on the characteristics of the solenoid and magnets:
Most unipolars I've disassembled don't actually have alternating north/south... which might be better. E.G. North is usually on top, south at the bottom. Then, toothed, a bit like gears. OTOH, if viewed as a projection, I guess they do alternate. And the windings cover both halves...
I'm 50/50 on thinking this'd work. The other half says both motors would find a steady-state position they'd want to stay in, and trying to rotate one by hand would be resisted, just as if the motor was driven normally; the influence of one's slight flux-change would be minor in comparison to the winding currents. oh, and about 20% that I'm way off... so, 40/40/20, I guess.
(Now adding text at the top... it seems to have ... nope... screenshot of typing blind.... at bottom)
while we're at it.. when I enter a log it skips right from the title to the content...
Here's me replying on the feedback page:
And here's me *now*:
... one or two lines of visible text-entry ain't so bad... but say... now I'd like to add a paragraph at the top... scrolling...
Here's me entering the first (added) paragraph (for some reason it's not visible while i was typing):
Anyways... editing/entry is a crapshoot, especially editing. Especially near the top. The floater pops up after scrolling, takes just enough time to click where you want the cursor, but then the floater interferes and you wind up entering a latex equation or in html view, etc.
This is by no means all inclusive a list...
That said... it does seem to have improved... but still difficult to use.