> Of course, for the utmost accuracy one would run any crystal > oscillator 24/7 and not want any breaks in power. But I think the > mechanical play on the hands is more significant than errors in the > crystal oscillator - at least on my clock.
Depends on the temperature and the crystal. The 32 KHz crystal in my PC swings by about 2 PPM per 10 degrees F. My junk room where the computer is located swings by about 10 F over a day. http://www.megapathdsl.net/~hmurray/ntp/drift.gif (Or at least did when I made that graph.) I think that's a cheap watch crystal, but I assume somebody gave some thought to temperature stability. It might be optimized for wrist temp rather than room temp. > I believe Big-Ben in the UK can be corrected by adding pennies to it, > so providing an upwards force. That is what I am told, but I must > admit it seems a bit unlikely. Perhaps possible if there are a lot of > pennies there. Apparently this is done, as it allows corrections > without stopping the clock. I've heard that story before, probably from Dave Mills. A quick google easily finds it. This URL http://news.bbc.co.uk/1/hi/uk/1501943.stm says a penny is good for 2/5 second per day, ~5 PPM. If we knew how big a penny was and assume the density of the pendulum is the same as a penny and assume something about the shape of the pendulum, say cylinder with dia equal to height, then we should be able to compute the size of the pendulum. -- The suespammers.org mail server is located in California. So are all my other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited commercial e-mail to my suespammers.org address or any of my other addresses. These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
