[time-nuts] Another "atomic" clock question
csteinmetz at yandex.com
Mon Mar 3 19:51:54 EST 2014
>If do have an external frequency reference then the crystal itself
>makes a good thermometer. So why not use THAT thermometer to
>control the heat added by the resister. Such a system would respond
>to changes in ambient temperature by adjusting the power in the
>resister. We don't even have to care if the crystal's temp-co is
>nonlinear because we are using a very small temperature range, so
>small it looks linear.
>I'll build it. Can you or anyone else subject a simple XCO
>schematic? Hopefully SIMPLE. What I need is a design that can be
>pulled down a few PPM so that I can raise it back with a bit of
>heat. I will have to be kept at a temperer above the hottest it
>will ever get inside the house, maybe 100F.
See below or attached (hopefully). L and C are chosen to resonate at
the crystal frequency with XC and XL in the general vicinity of 100
ohms to 1k ohms.
What you are proposing is a disciplined oscillator using the oven
setpoint as the control input.
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