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From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: Magnetic force
Date: Fri, 20 Sep 2024 04:33:45 -0700
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On 9/20/2024 1:57 AM, Liz Tuddenham wrote:
>> I suspect the adhering "metal" piece has to be on the skin
>> of the device as the magnetic field falls off quickly with
>> distance -- diluting the ability of the cable to remain
>> EXACTLY where desired.  A "decal" over the surface likely
>> would be tolerable...
> 
> Would a rounded bump on the device be acceptable?  A matching hollow in
> the cable end could then locate over it.

It would depend on how "rounded" the bump was.  And, how
tightly the "insert" matched the "equipment" plane.

When not "mated", the "bumps" are most often touched
(think of them as buttons and indicators when not acting
as communication ports).  E.g., the emitter normally
visibly indicates "status"; "touching" it acts to
invoke IDENTIFY/TRAP/RESET/POWER/SHUTDOWN functions.
So, the bump makes it easier to find with a fingertip
(otherwise, you have to be able to perceive the
difference between the glass of the jewel and the material
of the case)

Oils (and dirt) from hands will want to accumulate on those
surfaces.  Easily wiping them clean has to remove ALL traces
of that crud (because the person cleaning them may not be
able to SEE them -- blind/visually impaired -- but, others
*will* and would notice how grimey it appears)

[Imagine being blind and someone asks to use your toilet...
are you ever *sure* that they don't come out totally
disgusted by what THEY saw that you *haven't*?  <ick>]

> Something like this:
> http://www.poppyrecords.co.uk/other/Connector.gif

That's sort of what I was thinking though I was imagining the
magnet on the cable end (because there can be many such
ports in close proximity to each other -- 5/8" apart, hence
the limit of 1/2" -- but only one cable end).

I imagined the bump as being the glass piece with the
*detector and emitter* behind it (internal to the
"equipment") and an annular ring surrounding/framing
the glass jewel.  The ring magnet would be on the
cable end with an inner diameter just larger than
the glass jewel.

In the case of an attached *dongle*, there would be a
corresponding detector and emitter in the dongle.
For a cable, fiber could suffice over short distances
(else put the electronics on the end of the cable).