From: "Michael Rigby-Jones" <mrjones@NORTELNETWORKS.COM>
> >
> I thought the "wands" used a type of SPDT switch to detect the ends of
it's
> motion so it can sync the output to give a steady display. Imagaine a
> springy strip of metal with a weight attached, and two stationary contacts
> either side.  When waving the wand, one or the other contacts will be
> arranged to close at the point of maximum acceleration (at the change of
> direction).  By measuring the time between switch closures, the rate with
> which the LED's output the diaply data can be varied to get a fairly
static
> display, irrespective of how fast the wand is waved.  By having two
> contacts, you can tell which direction the wand is moving so you can spit
> the message out backwards in one direction to double the refresh rate.

Yes, but this is a display staff, and spins in one or other direction while
being used. The transitions are few.

I am not contemplating words as part of the display at the moment, because
of the requirement for them to appear at the right end of the staff at the
right moment.

I know the type of switch you mean though, commonly sold as tamper sensors
for car allarms.

--
cw

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