[time-nuts] A different timenuts interest
hmurray at megapathdsl.net
Thu Jul 22 16:18:56 EDT 2010
time-nuts at kasperkp.dk said:
> As a kid, I did a self sustaining pendulum with no moving parts and no
> The bob was suspended by two parallel wires, lacquered together, and
> shorted at the bob end. As the bob passed over the center, a one-shot sent
> a good-sized current pulse through the wire, heating it, making it slightly
> longer, and then shrink again as it cooled at the outside of the swing.
> For a heavy pendulum, and thick wire, the time constant in the cooling
> phase will likely make this infeasible.
That sounds like a good excuse to build a bigger and more impressive
pendulum. You need a longer wire so it has a longer period and enough time
to cool off.
Does anybody know how much piezo positioners cost, or where to get them
cheap? I'm not looking for a fancy gizmo that takes many tiny steps, just a
something simple that will vary the height slightly.
Maybe build one from several piezo noisemakers.
Here is the fun part. You can also use it as a sensor to measure the
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