IMHO, gluing magnets to moving parts makes them susceptible to magnetic fields, such as variations in the Earth's field at 10E-7, as TVB pointed out.
Had I the means to work with fused quartz and a suitable pivot, I would mount two photocell / LED pairs about 20 to 30% of the bob's swing apart. I'd break the beams with a fine wire, so the cell did not go completely dark. Then I'd work out a program to locate the center of the optical signal and time the interval between those centers. Using an incredibly precise physical adjustment, I'd align it so the outside intervals are equal. Call the sensors A and B. The interval between A going out and A coming back is proportioal to the distance from A to the end of the swing. And so it is for B. Now physically adjust the sensors so that A to A is precisely equal to the interval B to B. If the distances to the ends of the swing are equal, then the center is located at 1/2 the interval A to B. The interval B to A will be exactly the same as A to B if gravity is the only thing accelerating the bob, even if A and B are not centered on the swing. I'd like to try electrostatic impulsing, if I can keep charge from building up on the rod. There'd be no problem timing the impulse. The impulse would be tiny for a high Q system, or the pendulum could run free for many swings before being impulsed. I'd like to reduce the bob mass to 10 grams or so, if I could find the right suspension. Hmm, perhaps an electrostatic suspension? Simple enough to shield the vacuum tank. With precision timing electronics, I don't need a one second swing period. Interesting? Bill Hawkins _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
