[time-nuts] accurate portable time source

Ronald Held ronaldheld at gmail.com
Sat Dec 29 15:31:51 EST 2007


Brooke:
   You have been thinking about this longer than I have. I presume you
have not tried to make any prototypes?
                                       Ronald

Message: 1
Date: Fri, 28 Dec 2007 15:19:49 -0800
From: Brooke Clarke <brooke at pacific.net>
Subject: Re: [time-nuts] accurate portable time source
To: Discussion of precise time and frequency measurement
       <>
Message-ID: <47758495.7070707 at pacific.net>
Content-Type: text/plain; charset=us-ascii; format=flowed

Hi Ronald:

Here are a some of ideas for the heart beat for a LCD based clock like the ones
I've been developing.

Best) A Vectron EX-380 series Vacuum OCXO only draws 0.35 Watts and if the 5
volt version that's only 70 ma.  So a single AA would have enough energy, three
AAA Ni-MH would be great.  That was the good news.  The bad news is that they
are made of unobtanium (i.e. very expensive or need to be bought in large lots).

Good) An alternative is the DS3231.  This is an advanced version of the DS32khz
TCXO and is adjustable to 0.1 ppm using the digital serial interface.
Provision for a coin cell back up battery.

unknown) One of the DS3231 parts, in a thermal enclosure that has a time
constant in excess of 24 hours.  I think it's about the size you request.  A
temperature sensor changes the divisor based on calibration data.  Sort of a
doubly compensated device TTCXO or T2XO.  I like this one for a
practical product.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam



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