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Thread: watch crystals from cheap watch for rtc

  1. 18th May 2004 10:23 AM #1
    JunglePython
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    Default watch crystals from cheap watch for rtc

    I saw some cheap watches(2 for $1).

    Do all digital watches use 32.768kHz crystals or do they vary?

    Can these be used in PIC projects(eg. RTC)?

    Would it be a bad idea to use crystals from a cheap watch?
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  2. 18th May 2004 11:14 AM #2
    Matt(Pic progger)
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    :wink:
    All the watches I have seen use them, but your pic will run very slowly......32khz/4 or 8khz :?

    :idea: Buy the watches, sell em on ebay, and save up for some new higher speed crystals!! :wink:
    Regards


    MATT!
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  3. 18th May 2004 11:51 AM #3
    Nigel Goodwin
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    Quote Originally Posted by Matt(Pic progger)
    :wink:
    All the watches I have seen use them, but your pic will run very slowly......32khz/4 or 8khz :?
    That's the point!, power consumption is directly related to clock speed, so by using a slow clock you reduce consumption drastically. Obviously the program will run fairly slowly, but often that doesn't matter, battery life can be far more important.

    PIC's even have an LP clock mode (Low Power), designed to use 32KHz crystals.
    PIC programmer software, and PIC Tutorials at:
    http://www.winpicprog.co.uk
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  4. 18th May 2004 12:11 PM #4
    Matt(Pic progger)
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    :wink:

    Yeah, I got that 1 nigel, sorry, just in a bit of a "off at a tangent" kinda mood today, you may have trouble staying with me..... not that you probably would want to....

    OK so the "grown up" answer, don't sell the watches on ebay and make a fortune, strip them down, solder very fine wires to the very short ones on the ripped out watch crystals, fit them to your PIC circuit and marvel at the fact that for 1/2hr's work you have saved 20Cents and re-cycled an otherwise redunadnt piece of stock.... :wink: :lol:

    Oh yeah, and make yourself some timers, bit like a watch really only not as pretty and probably more painfull to wear on your wrist...... :wink:

    So in answer to the original question........ what was it again??? :P
    Regards


    MATT!
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  5. 19th May 2004 02:10 AM #5
    PeterK
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    Default 32 k xtals

    Hi Jungle Python,

    Rocky in Melbourne sell 32 k xtals, excellent price.

    Rocky.com.au
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  6. 19th May 2004 04:24 AM #6
    JunglePython
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    brilliant!

    Thnx a bunch.
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  7. 19th May 2004 04:36 AM #7
    JunglePython
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    Hey I tried rocky.com.au and it came up with nothing.

    Are you sure about that url.

    Cheers

    Luke
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  8. 19th May 2004 12:56 PM #8
    Fletcher
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    try http://rockby.com.au
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  9. 19th May 2004 08:52 PM #9
    JunglePython
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    Thank you
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  10. 21st May 2004 02:47 AM #10
    PeterK
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    Default Rockby and rocky

    Sorry Jungle Python

    Missed a letter.

    Peter
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