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[DPRG] vibration sensor gizmo

Subject: [DPRG] vibration sensor gizmo
From: . zappepcs at earthlink.net
Date: Sun Oct 5 22:07:01 CDT 2003

In the late 80s, there was a company in London that was using a similar material
to weave a cable into chain-link fences, using the piezo properties to make 
Time Domain Reflectometry type measurements, pinpointing the disturbance 
location on the fence line. Not only pinpointing the location, but often the size of
the disturber... such as dog or small animal or human etc.  I'm not sure how 
successful they were at marketing this product. 

I think we have all seen piezo-electric lighters? If I'm not mistaken, I read somewhere
that piezo materials were being tested in touch sensors for robotics, based on the
electric feedback from pressure (deformation of the material) allowing the machine to
gauge pressure being exerted on an object.

I'm certain that we will hear more and more about such materials. Materials engineering
is a fascinating area of R&D, but only for the few, the brave, the geeks...   :)

SZ

-----Original Message-----
>From: Earl Bollinger <earlwbollinger at comcast.net>
<snip>
I do have to say that this vibration sensor gizmo is really really
amazing.
It's sort of one of those, "Wow I never seen something like that
before!" type of thing.

>From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org] On Behalf
Of Kipton Moravec
<snip>

I have a interesting vibration sensor.
http://www.msiusa.com/download/pdf/english/piezo/ldt0.pdf

You can get it from Digikey.  It is not quite sensitive enough  But we
put 
a piece of masking tape on it to lengthen it and it became sensitive 
enough.  We used a comparator in the AVR.  Because of the sensitivity,
we 
ended up comparing it to ground.  It is a little piezo device which
looks 
like a capacitor. As it flexes it generates a positive voltage in one 
direction and a negative voltage in the other  Fortunately a flex in the

positive direction is enough to detect.



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