Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: rickman Newsgroups: sci.electronics.design Subject: Re: OT: Current standard for watch precision Date: Tue, 7 Feb 2017 02:43:33 -0500 Organization: A noiseless patient Spider Lines: 58 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Tue, 7 Feb 2017 07:41:48 -0000 (UTC) Injection-Info: mx02.eternal-september.org; posting-host="b6443822665b11d600c80c1d7678cd9f"; logging-data="20768"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX185etdTncKM9w0frbzOn+0l" User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 In-Reply-To: Cancel-Lock: sha1:sqAk8ylBg1rQ2WduRo9oPcHYFDE= Xref: csiph.com sci.electronics.design:446610 On 2/7/2017 12:50 AM, Jasen Betts wrote: > On 2017-02-06, Pimpom wrote: >> On 2/6/2017 11:43 AM, Phil Allison wrote: >>> Pimpom wrote: >>>> >>>> >>>> What would be considered a "good" wristwatch today in terms of >>>> timekeeping precision? Forget about build quality, price, shock- >>>> and waterproofing, etc. >>>> >>>> Half a century ago, a wristwatch with a-minute-a-month accuracy >>>> might have been labelled a chronometer. What standard would you >>>> apply now? >>>> >>> >>> ** The Quartz standard, of course. >>> >>> Goolge has heaps of info on this topic: >>> >>> http://www.chronocentric.com/watches/accuracy.shtml >>> >> Perhaps I should rephrase the question. I meant to ask what level >> of accuracy would be considered good for a consumer wristwatch >> nowadays. >> >> For example, I bought a Chinese analog-digital wristwatch from >> www.aliexpress.com last month and have been monitoring its >> accuracy. I do this by comparing it to a freshly synced computer >> clock. It's now exactly one month since I synced it to the >> computer clock. The analog section is ahead by 6 seconds and the >> digital one is behind by 35 secs. The errors may not be linearly >> cumulative but I think it's pretty good for a US$7 watch. > > about half a second per day was typical of inexpensive quartz crystal > watches in the 1980s > > About 1987 I decided watches were't worth the bother, especially > cheap watches that pulled hairs from my arm. I remember a *long* time ago I had one that had a trimmer cap in it. I would tweak that until it barely gained or lost time at all. But like all watches on my wrist, eventually it got beat up and quit working. I also remember building a clock with a vacuum florescent display with a trimmer. I was adjusting it by beating a 60 Hz output against the power line. I could get it very, very close, but then ten or fifteen minutes later it would drift again! It took me awhile before I realized that wasn't the clock, it was the power line. lol Does the power line still drift like that? Is there a reason why it would in this day with the many sources of accurate timing available? I'd expect the many generators could do a much better job of not running up and down in frequency so much, or is this an inherent aspect of a widely distributed network? -- Rick C