holrum@hotmail.com said: > Basically the solenoid nudged the pendulum There was an article in Scientific American many years ago. They used a magnet mounted on the end of a stick attached to the pendulum arm. The arc of the magnet swung through a hole in the middle of a solenoid coil. A pulse on the coil at the right time provided the nudge with no physical contact. -- These are my opinions. I hate spam.

Science Madness has a PDF of the book - Projects for the Amateur Scientist by SciAm columnist C.L. Stong. The pendulum is on page 290 http://www.sciencemadness.org/library/books/projects_for_the_amateur_scienti st.pdf Dave > -----Original Message----- > From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf > Of Hal Murray > Sent: Saturday, January 10, 2015 15:09 > To: Discussion of precise time and frequency measurement > Cc: hmurray@megapathdsl.net > Subject: Re: [time-nuts] Mechanical 1PPS Oscillator Disciplining > > > holrum@hotmail.com said: > > Basically the solenoid nudged the pendulum > > There was an article in Scientific American many years ago. > They used a > magnet mounted on the end of a stick attached to the pendulum > arm. The arc > of the magnet swung through a hole in the middle of a > solenoid coil. A pulse > on the coil at the right time provided the nudge with no > physical contact. > > > -- > These are my opinions. 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.

On 1/10/15 3:08 PM, Hal Murray wrote: > > holrum@hotmail.com said: >> Basically the solenoid nudged the pendulum > > There was an article in Scientific American many years ago. They used a > magnet mounted on the end of a stick attached to the pendulum arm. The arc > of the magnet swung through a hole in the middle of a solenoid coil. A pulse > on the coil at the right time provided the nudge with no physical contact. > > or a coil under the pendulum bob, which is ferrous, a technique used in some large Foucault pendulums I didn't realize you can actually buy them as a sort of catalog item.. http://www.academypendulums.com/ They put the drive at the top. The most fascinating thing is the list of 122 pendulums they've installed http://www.academypendulums.com/foucault-pendulum-displays.html and some of the places they are.. there's a goodly number of museums, of course, but some other things..Wineries, Banks, Malls? the one in the Smithsonian was removed some years ago.. Very simple design the schematic (and the user manual including tuning instructions) is on the website under "manuals" Just a photodetector driving a solenoid, which apparently draws 300 mA from a 120VAC line. I haven't found details on the coil or armature design, but plenty of pictures.