nf165636@cisunx.UUCP (meyers m) (06/16/87)
How do the clocks (and clock radios) that run on main power (110/60 Hz)
count the time ? Especially those that use battery backups. In this case
do they use a quartz crystal ? Does that mean that these can be used
on 110/50 Hz or any other frequency ? Any info will be appreciated.
--
Michael Meyers {allegra,bellcore,cadre,ihnp4}!pitt!cissunx!nf165636 UUCP
Comp & Inf. Systems cisunx!nf165636@pitt.CSNET
University of Pittsburgh pitt!cisunx!nf165636@cadre.dsl.pittsburgh.edu
--
Michael Meyers {allegra,bellcore,cadre,ihnp4}!pitt!cissunx!nf165636 UUCP
Comp & Inf. Systems cisunx!nf165636@pitt.CSNET
University of Pittsburgh pitt!cisunx!nf165636@cadre.dsl.pittsburgh.edugnome@oliveb.UUCP (Gary) (06/17/87)
in article <3622@cisunx.UUCP>, nf165636@cisunx.UUCP (meyers m) says: > How do the clocks (and clock radios) that run on main power (110/60 Hz) > count the time ? Especially those that use battery backups. In this case > do they use a quartz crystal ? Does that mean that these can be used > on 110/50 Hz or any other frequency ? Any info will be appreciated. AC driven clocks generally get their clock timing from dividing-down the 60Hz to the 1Hz seconds-clock. Some clocks have a little circuit that allows the clock to ride-out short power failures. Often it is a cheap, low accuracy oscillator that "locks" to the 60Hz (when available) and self oscillates at about 60Hz when the line power is gone. Most crystal driven clocks are battery-only. Note, I said most. So, in general, if it plugs into the wall, it won't work too well in other countries with 50 hz. (Some have a switch for 50/60Hz, though). Gary
smk@sfsup.UUCP (06/18/87)
In article <3622@cisunx.UUCP>, nf165636@cisunx.UUCP writes: > > How do the clocks (and clock radios) that run on main power (110/60 Hz) > count the time ? Especially those that use battery backups. In this case > do they use a quartz crystal ? Does that mean that these can be used > on 110/50 Hz or any other frequency ? Any info will be appreciated. > > -- I thought that the battery backup in my alarm clock would make it a lot easier to take on vacation; after all, all I would have to do is plug it in, right? What I did find out was that any similarity between the actual time and the clock's time was purely coincidental.
rmrin@inuxh.UUCP (06/19/87)
> > How do the clocks (and clock radios) that run on main power (110/60 Hz) > count the time ? Especially those that use battery backups. In this case > do they use a quartz crystal ? Does that mean that these can be used > on 110/50 Hz or any other frequency ? Any info will be appreciated. > The ones I am familiar with count the cycles of the power line. When they go into the backup mode an internal oscillator takes over which can be quite inaccurate. One of mine loses a couple of minutes an hour in the backup mode. I would suggest checking them after a fairly long power failure.
fish@ihlpa.UUCP (06/20/87)
In article <3622@cisunx.UUCP>, nf165636@cisunx.UUCP writes: > > How do the clocks (and clock radios) that run on main power (110/60 Hz) > count the time ? Especially those that use battery backups. In this case > do they use a quartz crystal ? Does that mean that these can be used > on 110/50 Hz or any other frequency ? Any info will be appreciated. Most cheap digital clocks and clock radios with battery backup use the line frequency as a primary time base, and have an internal oscillator as the backup. The oscillator is not crystal-controlled, and will drift considerably, causing the clock to lose or gain several minutes in a day. However, they are usually accurate enough to maintain the correct time during brief power outages. -- __ / \ Bob Fishell \__/ ihnp4!ihlpa!fish