[time-nuts] My Casio G-Shock watch and other fun stuff

Brooke Clarke brooke at pacific.net
Thu Jun 21 12:09:07 EDT 2007

Hi Tom:

I've recently been interested in bats and have a heterodyne type ultrasonic 
down converter to listen to the local ones.  When tuned near 32 kHz I can hear 
the crystal in the IMP2 slave clock driver.

I'm looking into building an ultrasonic microphone based on the transducer that 
was used in the Polaroid Sonar cameras.  These have a much broader frequency 
response than the electrect condenser microphones used in the bat detector, but 
need a clean 200 VDC bias supply.  This setup could just "listen" to the 
crystal in a watch.

http://www.prc68.com/I/Bats.shtml <- Bats
http://www.prc68.com/I/SETSC.shtml#IMP2 <- IMP2 slave clock driver
http://www.prc68.com/I/PSOSC.shtml  <- Removing the sensor from a camera

Have Fun,

Brooke Clarke

Tom Van Baak wrote:
>>Hi Tom:
>>How was that data taken with, a Microset or some other way?
>>It's interesting in that it shows the rate was not adjusted.
> Brooke,
> Since that watch is quartz analog I used a magnetic pickup
> to detect the 1PPS. Amplified, this then went into a 53131A
> counter using a GPS 1PPS as reference. I collected data
> for a couple of weeks, including hiding the wristwatch inside
> a metal soup can to force it to fail to sync with WWVB.
> It's harder to pull this off with a LCD digital watch. One must
> resort to optical detection (as Jim described in this thread)
> or possibly direct audio or RF monitoring of the faint 32 kHz
> oscillator signal.
> /tvb
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