[time-nuts] Frequency referenced temperature regulator

[Javier Herrero]

Hi,

Why not use a more conventional approach using a good thermistor and a 
PWM IC? I built some in the past with Peltiers and an LM3524 for cooling 
a photomultiplier in a nitrogen oxyde analyzer, and the result was quite 
good. I also used the same approach (but not with Peltier) for heating. 
Of course, the frequency stability was not time-nuts grade... not even 
near :)

NTCs like the YSI 44031 have very good repeatabilty, and the resistance 
vs. temperature curve is quite steep, so you really don't need too 
stringent voltage stability needs.

Regards,

Javier

El 08/11/2010 16:04, Poul-Henning Kamp escribió:
>
> 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 ?
>

-- 
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Javier Herrero                            EMAIL: jherrero at hvsistemas.com
Chief Technology Officer
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