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The Song of Velocity  -  I just had to do it. Take a 5,000 pulse per
rev shaft encoder and attach a 3 foot arm with weight at the end. Mount this
assemble to a stable wall. Connect the output of the encoder to a small
amplifer. One to three watts will do. Then connect to a speaker with a 8
inch or larger woofer. When you give the pendulum a push the motion is
translated to a pitch. The pitch now represents velocity. Hearing the pitch
and seeing the motion is a very engaging experienc for a young mind.
     Add stops to limit the travel of the arm. A encoder with less pulses
per rev can be used but the upper limit of the pitch will be reduced. If you
use a encoder with good bearings the velocity sounds will last for 3 to 5
minutes. Because the output of an encoder is a square wave even the last bit
of movment can be heard. Search the surplus catalogs for a resonable priced
unit. Pick a unit that has a 1/4 inch or larger shaft.
      This is one of those simple but effective demonstrations that have to
be shared. If you need electrical or mechanical drawings let me know.

        Roger Sonntag - GSE  - [log in to unmask]   585-338-7001

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