Re: Repeatability of microswitches

Hall effect device:

Device is a SS441A (Honeywell) from Newark at about $2.40 ea. Magnet is
a 5/16 x 1/2 or so ceramic
of unknown origin.

I glued the magnet to a 1/4" dowel pin (superglue is nice stuff)and put
in the spindle. then clamped the wires to the
device in a vice. Used a Fluke meter to indicate switching.
Not as nice as a LED but cheap and dirty, well at least dirty. Bias was
9.52 V with a 10K
pullup. Nothing magic about these numbers, it is just what I had laying
around.

At a gap of 0.10" repeatibility was 0.0002" or so (my resolution limit
on the glass scale) with a
hystersis of 0.66" i.e. from latch to release.
Ditto at 0.20". Results were a little sloppier at a gap of .30"; range
of 0.0012", hystersis of
0.55".
Device would not trip with a gap of 0.40".

At this time I have no way to determne dx/dt effect of this setup but
assume that there might be
some. All of this data was done with an incremental approach like I was
using an edge finder.
They do switch quickly, will sink enough current to be reasonably quiet
and have no bounce.

Hope this helps.

dave