Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!decwrl!ucbvax!hplabs!hp-pcd!hpcvca!charles
From: charles@hpcvca.CV.HP.COM (Charles Brown)
Newsgroups: comp.sys.amiga.tech
Subject: Re: TICK and J300
Message-ID: <1410017@hpcvca.CV.HP.COM>
Date: 15 May 89 23:49:08 GMT
References: <3319@hplabsz.HPL.HP.COM>
Organization: Hewlett-Packard Co., Corvallis, Oregon
Lines: 24

>> Normally, the A2000 takes its 1/60sec  (or 1/50) ticks from the power
>> lines, which should be fairly accurate.  When you switch the jumper
>> to the "A500" position your A2000 then takes its ticks from the
>> video. Which is not quite as accurate.

> Unless there is something more going on than what you stated, this
> is inaccurate. Power line frequencies drift quite a bit, although
> the utilities usually take some care to make the drift average out to
> approximately zero over a period of time.
> 	Doug

Not correct.  The power companies are already quite good during the
day.  Then near midnight they adjust their frequency so that the total
number of cycles in the day is right on.  You should see no drift
unless you are experiencing power outages.  Naturally the power
company cannot adjust the main station to compensate for an outage in
just one neighborhood.  Considering that most outages (in my
experience) last less than 2 seconds, with a mechanical clock you
would only notice that your clock drifted over a matter of months.
--
	Charles Brown	charles@cv.hp.com or charles%hpcvca@hplabs.hp.com
			or hplabs!hpcvca!charles or "Hey you!"
	Not representing my employer.  This article is based
	exclusively upon and generated by transmission line noise.