----- Original Message -----
From: "Denny Esterline" <firmware@TDS.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Tuesday, March 02, 2004 5:12 PM
Subject: [EE:] Vibration sensor?


> Hey guys and gals,
> I need some sensors to pick up vibration. Needs to be sensitive in two
> axis, and capable of detecting being bumped with less than 1/8 inch
> movement. It'll feed a PIC so I can work with most any output, but I only
> need a single pulse when it's bumped.
>
> Right now I need about a dozen, but eventually I might need several
> hundred. And yes I could do it with an accelerometer from analog, but I
was
> hoping for something simpler/cheaper.
>
> Ideas?
>
> -Denny
>

I bought a cat toy that is a little ball, smaller than a golfball that has
two flashing LEDs.  There is a small "vertical" wire soldered to the circuit
board and around it is a coil of wire.  Normally the two don't touch but if
you tap the ball they touch.  This triggers the flashing of the LEDs for the
next 30 seconds.

This may not be sensitive enough for you because you can pick up the ball
and wave it around and it won't start to flash.  It seems to take a sharp
movement to flex the coil.  With the ball on the floor I can tap it with my
finger and it starts to flash.

I play with it more than the cat does...  Her favorite toy is a length of
1/4" dowel rod.

Rob Young

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