h a l f b a k e r yExpensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.
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No fully-equipped geek's desk is complete without the new BorgCo plasma-sphere touchball.
Connecting to a USB port, the pointing device looks like a transparent hemisphere embedded in a low, heavy conical base.
The hemisphere contains a plasma discharge coil; glowing tendrils reach out to the inner
surface. If touched by a fingertip, the tendrils instantly consolidate into a single bright line.
The outside of the hemisphere is touch-sensetive, and acts like a trackpad or touchscreen. Moving a finger over the surface causes corresponding movements of the pointer on-screen. Tap gestures are equivalent to left mouse-clicks; using two fingers allows right-clicks to be made, or stretch-shrink-zoom, page up/page down, rotation, or scroll - according to the user's preference.
The device is expensive, unnecessary, and delivers no more actual functionally than a regular feature mouse or trackball.
But it looks REALLY cool ...
Plasma globe
https://en.wikipedi...g/wiki/Plasma_globe
The basis of the system [8th of 7, Feb 05 2017]
SAW
https://en.wikipedi...rface_acoustic_wave
Useful [8th of 7, Feb 07 2017]
Trackballs
https://www.google.....0i10k1.umEsc3gZCDg
The idea is to work mostly like these, but non-moving. [neutrinos_shadow, Feb 09 2017]
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This would be cool, but mostly cool if working with 3D graphics packages. |
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I note, incidentally, that my regular trackpad does not like having a plasma sphere near it. I suspect that making a tracking surface that worked reliably despite huge discharge voltages on the inside would be tricky. Howevertheless, I am happy to award this bun on spec. [+] |
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I would suspect (as [MaxwellBuchanan] also noted) that the tech for tracking wouldn't play nice with the high voltage bits.
BUT: as it is a transparent dome, just stick a camera (or 2 or 3, just to make sure) into the flat base of the hemisphere, to visually track where the touch is. (Er... assuming the high voltage doesn't mess with cameras, too. The chip can be moved further away using a couple of lenses, if required.)
When messing around with my own plasma globe (of course I've got one...), I've noticed that the "re-direction" of the discharge (towards my finger/s) begins before I actually reach the glass. So you gain an equivalent 3rd dimension (slight distance, as opposed to pressure, for example). |
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High voltages wouldn't affect a SAW touch surface. |
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SAW looks good.
Another thought: the high-voltage discharge is also high frequency. This would presumably cause vibrations (due to localised heating and/or EM forces) at the point of contact. (Rather than using a separate vibration source.)
Still not sure about how to do multi-touch (other than possibly my previous camera mod).
This is getting disturbingly close to bakeable. |
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//I note, incidentally, that my regular trackpad does not like having a
plasma sphere near it. I suspect that making a tracking surface that
worked reliably despite huge discharge voltages on the inside
would be tricky.// |
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I'm sure it would destroy a standard capacitive touchscreen
controller, if that's what you mean. |
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However a non-trivial amount of AC current flows 'through' the
glass at the point where you touch a plasma globe. I'd guess that a
pair of grids of electrodes on the inside and outside of the glass
would register a substantial voltage differential when touched by a
finger. Designing a controller circuit to detect this differential
shouldn't be beyond the wit of man. |
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//The device is expensive, unnecessary, and delivers no more
actual functionally than a regular feature mouse or trackball.// |
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Agreed. In addition, it is far more fragile. [+1] |
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//delivers no more actual functionally//, if you're not paying attention,
that is. |
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Get some of those LED light-up shoes. Wear them while touching the
plasma ball. Watch the LEDs... |
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OK, so it's not yet a -useful- function. But your mouse or trackball
can't do that. |
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Err...err...why not just a plasma globe, and stick cameras inside the globe? |
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The cameras would have thin vacuum deposition film of gold or something conductive to prevent being zapped...then it'd be 360 degrees accessible all over. |
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Apart from where the stick holding the thing up joins the sphere. |
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// You'd need a spherical or globular screen // |
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.... or good-quality VR goggles ? |
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Good lord. Haven't you upgraded to a proper palantir yet?
They're not all that difficult to find. One is just sitting
unused at the bottom of the river Anduin I think... |
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This is very clever. Figure out how to make it work and
Kickstarter that baby. |
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// This is very clever // |
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Of course it is. We thought of it. |
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// They're not all that difficult to find // |
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We've got two ... but the sound's gone on one of them, and the other only ever shows re-runs of Dallas and Knot's Landing (Altho sometimes you can get Kojak, or Magnum P.I.). |
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It came in a box of stuff we bought off an old bloke in a pub. There's all sorts in there, we've never really looked at it. There's a couple of rings, an old mirror, some funny looking broad beans in a bag, a dirty old oil lamp, and an antique tinderbox ... we only bought it for the palantirs, the rest can go to a charity shop. |
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Whatever you do, don't rub the lamp. You'll take off the patina and destroy any value it might have. |
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[Ian Tindale], have you never seen/used a trackball? It's a regular input device; no need for a spherical screen. |
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Surely a mouse isn't like a plasma discharge ball in a different way? |
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I still don't know why you think it needs a spherical screen, though.
Trackball: spherical surface that you interact with to move a cursor on a flat screen.
[8th of 7]s Plasma-globe Touchball: spherical surface that you interact with to move a cursor on a flat screen.
Same as:
Mouse: thing that moves with you to move the cursor.
Trackpad: thing that doesn't move with you to move the cursor. |
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Completely off topic, but does anyone happen to know if a neon sign transformer is capable of delivering a lethal shock? I have a very good reason for asking. |
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Hmm. In which case, are those Jacob's Ladder things (I mean the V-shaped antennae with the rising arc between them) lethal, or do they have some other sort of protection? The voltage presumably needs to be fairly high, and I imagine the current through the arc can't be that low... |
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Yes, the large ones are potentially (ha, ha) lethal. |
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Then again, if you go poking bits of your body into a gap between two bare metal rods with a big, bright electric arc sizzling between them, you're probably stupid enough that your death will actually improve the quality of the gene pool. |
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If there's someone you need to off, Max, I do
happen to live near Detroit, and could fix you up... |
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That's kind, but my staff usually handle that sort of arrangement. |
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No, I was going to make a double-helical Jacob's ladder using an eBay neon sign transformer, and wanted to know how careful I ought to be. |
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Actually, on second thoughts, [Rayfo], can I give you a list? It'll take me a while to get it properly bound but then I'll Fedex it to you. |
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// make a double-helical Jacob's ladder // |
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The rods will need to diverge slightly, otherwise the arc won't "run". |
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I know. I'm also hoping that I can have metal base-pairs, with gaps where the hydrogen bonds would be. If I am unreasonably lucky, the arc should jump from base-pair to base-pair, as long as the vertical interval isn't too great. |
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No, probably won't work. The arc will hit the first "base-pair" and stick, because it seeks the shortest path; to move "up" the helix, it would have to move out to the support rods. |
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In a conventional Jacob's Ladder, the arc climbs the electrodes because it's hot, and lighter than the surrounding air, despite the gradually increasing arc length. |
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Yes, I know. However, even on a continuous Jacob's ladder, the arc tends to move in short jumps. |
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So, what's required is that the jump in moving from one base pair to the wider helix immediately above it is greater (in terms of electrical resistance) than the jump in moving from one base pair to the one above, bearing in mind that the ionized air has risen to help reduce the resistance between that next base pair. |
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There will be a geometry that makes it work. |
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[MaxwellBuchanan], you might be able to get your "base-pair jumps" to work if you use an intermittent power input.
You have a discharge across one "pair"; this ionises the air. When the power shuts off, this air is still hot and ionised (lasting for at least some undisclosed time-period). Being hot, it will rise. If you time the next "power on" step to coincide to match when the "hot path" aligns with your next "base-pair", you should get the discharge to work at that point.
It will need much calibration, experimentation and continual modification (and probably other -ations too...). |
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Whether you get the base-pair version working, or just a continuous double-helix discharge; please post video for us! |
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Nope, there's got to be a way to do it simply, with geometry. |
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The arc normally rises (on a regular Jacob's Ladder*), even though the gap widens. That's because the hot, rising ionized air means that the resistance is lower just above the arc's current (no pun intended) position, even though the gap is wider. |
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So, imagine two base-pairs, one above the other. Imagine that the gap between them is nearly the same, but the upper gap is very slightly wider. The same argument will apply as before: the rising, ionized air will make the resistance** lower between the upper pair than between the lower pair, and the arc will jump up. Remember, the arc is not a continuous thing - it can disappear from one place and appear in another place where the resistance is lower, without having to travel through the intervening very wide gap. |
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I guess step 1 is to make a regular JL with kinky wires - the arc should jump from in-kink to in-kink. If that works, the base pairs will work. |
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Sadly, though, I have sold my soul to lawyers for the next week. They want not only 100% of my time (which, of course, is why I am not here on the HB) but, inexplicably, they want me alive. |
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[* I'm sure it's not really called a Jacob's Ladder. A Jacob's Ladder is that wooden-and-ribbon toy.] |
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[**I probably mean dielectric constant when I say resistance.] |
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To ensure the arc doesn't jump to the "helix" part, you might have to insulate it; only leaving the base-pairs conductive. Otherwise you might end up with a (relatively) small gap in your base-pairs (compared to the width of the helices). |
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Gabriel electrodes might help with jumping between base pairs, though I'm not sure how to arrange them. |
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On a normal Jacob's ladder, the electrodes don't have to diverge all the way up, AFAIK. They just have to diverge sharply at the top to break the arc, so that a new one can form at the bottom. But if they have a point where they're closer to each other, or if the top divergence is too sharp, I could see the arc maybe getting stuck there, at least temporarily. |
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It's possible to make a Jacob's ladder in the shape of a ring (with constant spacing), with a magnetic field instead of convection to drive the arc around the circle continuously, though I forget where online I saw this. |
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I have actually seen a double helix Jacob's ladder before, though it was terribly built and didn't work well. I think it got posted on Hackaday, though. |
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My approach to touch sensing on the plasma globe would be visual. Put three cameras at the bottom, looking up into the globe around the electrode column. Shine IR into the glass (may need a feed structure added) to be totally internally reflected. Detect proximity by where the arcs concentrate, and touch by frustrated total internal reflection (as has been done for flat multitouch systems). Maybe replace the three cameras with one camera with a wide lens, though that would introduce depth-of-field issues. |
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A glass barrier inside the globe might be necessary to prevent the arcs attacking the cameras—just a divider between the spherical part and the roughly toroidal part around the base of the electrode column, with the toroidal part filled with a more insulative gas. (If you've taken apart a plasma globe, you'll probably know what I'm talking about there.) |
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