time-n...@kasperkp.dk said: > As a kid, I did a self sustaining pendulum with no moving parts and no > magnets:
> 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. Neat. Thanks. > 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 position. -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.