[time-nuts] Improving the stability of crystal oscillators

Don Collie donmer at woosh.co.nz
Mon Oct 15 21:31:14 EDT 2007

Hi Hal,
    I was thinking of attaching a temparature sensor [AKA Star Treck] to the 
cold side of a Peltier [what`s the other type? Are they available/better?] 
pile. and driving the pile from the output of some sort of servo loop to 
maintain a temparature of ,say , 0 Degree C.
     If you wanted a double oven, you could heatsink a small oven, 
containing the crystal, the oscillator, and buffer[s] to this, and use a 
second servo loop to raise the temparature of this to 25 Degrees C working 
against the Peltier. In this way, you could maintain the crystal, and 
circuitry at 25 Deg C., over an ambient temparature of 0 to ,say 70 Deg C.
    Yes, you can cut a crystal to have an inversion temp at 25Deg C. [well 
certainly with an AT cut - I`m not sure about the SC cut.]
Cheers,............................................Don C.

----- Original Message ----- 
From: "Hal Murray" <hmurray at megapathdsl.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Tuesday, October 16, 2007 5:49 AM
Subject: Re: [time-nuts] Improving the stability of crystal oscillators

> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+donmer=woosh.co.nz at febo.com RETRY
>> The resonator inversion temperature occurs at 70-80 degrees Celsius,
>> depending on the cut angles.
> Is there something magic about quartz that has a turnover in the region 
> that
> just happens to be handy for OCXOs?  Or is it the other way around: people
> chose the cut angle to get a temperature that works well for ovens?
> Could I cut a crystal with a temperature at (say) 0C or something handy 
> for
> Peltiers?
> -- 
> These are my opinions, not necessarily my employer's.  I hate spam.
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