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Can I change the DS1307's crystal
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Please be positive and constructive with your questions and comments.

Can I change the DS1307's crystal

by Winchell Chung on Sat May 31, 2014 7:11 pm

I was admiring the DS1307 Real Time Clock breakout board kit. The crystal is a 32.768 KHz crystal.
Am I correct in assuming that if I swap the crystal with one of a different value, it will affect the clock speed?

What I am trying to do is make a sidereal clock, which is used in astronomy. Sidereal time runs faster than Greenwich Mean Time by about 3 minutes and 56 seconds per day. Which in theory means if I swap the 32.768 KHz crystal with a 32.858 KHz crystal the DS1307 will run sidereal time.

Assuming I can find such crystals, is it that easy, or are additional electronics required?
Winchell Chung
 
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Re: Can I change the DS1307's crystal

by adafruit_support_bill on Sun Jun 01, 2014 5:53 am

Interesting topic. Maxim has an app-note on crystal selection - if you could find one at that frequency.
http://www.maximintegrated.com/en/app-n ... .mvp/id/58
Here is one approach to the problem: http://www.jimbo.net/circuitfarm/2010/07/sidereal-time/

adafruit_support_bill
 
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Re: Can I change the DS1307's crystal

by Winchell Chung on Sun Jun 01, 2014 1:07 pm

Thanks for the links!

Sidereal clocks have a very limited market, all of it astronomy related. Generally only in astronomical clocks and telescope tracking motors.

I just so happen to have a couple of specialty crystals of the correct values. Though your jumbo.net link is very interesting
Winchell Chung
 
Posts: 59
Joined: Mon Sep 23, 2013 2:16 pm

Please be positive and constructive with your questions and comments.