[time-nuts] Frequency referenced temperature regulator

[Neville Michie]

A hint for using peltiers,
the resistive component in them has a problem with IsquaredR heating
so that better performance is obtained by running them on filtered DC.
PWM control works best if it is filtered to DC.

My choice for temperature control is a glass encapsulated thermistor,
there are some quite small ones that have very fast response and good  
ageing
performance.

Diodes and transdiodes also make good sensors and can come in good  
packages
with rapid response.

For us the best temperature standard is ice point and that is only  
good to 10 mK.
Anything better means a trip to a standards laboratory.

However, one is to be applauded for trying to link temperature to  
frequency,

cheers,
Neville Michie


On 09/11/2010, at 2:04 AM, Poul-Henning Kamp wrote:

>
> I'm contemplating building a small temperature control enclosure for
> testing various electronics.
>
> I have a handful of peltiers suitable for the purpose, and was
> pondering the right control mechanism.
>
> Most people would reach for a NTC, put it in a wien-brige etc etc.
>
> But since I happen to have access to much more stable frequencies
> than voltages, I thought of a different way:
>
> 1. Mount a X-tal-osc with really lousy tempco inside the enclosure.
>
> 2. Compare its output to a stable reference frequency.
>
> 3. Use the output of the phase comparator to drive the Peltier.
>
> It is basically a PLL where temperature is used as EFC...
>
> Has anybody tried that ?
>
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by  
> incompetence.
>
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