[time-nuts] Restoring GR 1120-AB Frequency Standard
Mike Monett
XDE-L2G3 at myamail.com
Thu Aug 21 15:07:43 EDT 2008
"Max Robinson" <max at maxsmusicplace.com> wrote:
>
>When I was at the university I saw and worked on a thermostatic switch that
>used a standard mercury thermometer. The little thing that clipped on to
>the thermometer was the capacitor in an oscillator. The detector for
>opening and closing the relay was a high Q tuned circuit. I saw them
>regularly because I had to keep teaching lab instructors how to tune them up
>before each use. In a controlled environment it might be possible to
>optimize such a circuit for stable operation and tight control. My
>intuition tells me that 1 degree is about as fine a control as you could get
>unless you had a very narrow range thermometer with a small capillary. You
>might be able to convert the existing thermostat to capacitive sensing.
>That is apparently what Magnus is suggesting.
>
>Regards.
>
>Max. K 4 O D S.
Optical might work better. Maybe use the lens and laser from an old CDROM.
It might be fun getting it to focus on the mercury column through a round
glass tube. Or maybe the glass wouldn't even pass the infrared. I got a bad
burn once picking up an empty wine glass that was sitting beside a
fireplace. But I understand new systems use a blue laser, which might work
even better.
I wonder what kind of temperature control it would give, and what the
long-term drift might be. Sounds like a fun project.
Regards,
Mike Monett
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