[time-nuts] Improving the stability of crystal oscillators

[Bruce Griffiths]

Brooke Clarke wrote:
> Hi Don:
>
> They are very inefficient to the point that a system that's supposed to cool 
> something may heat it because of all the heat generated by the module.
>
> It takes a huge amount of heat sinking or liquid cooling to get them to work.
>
> Have Fun,
>
> Brooke Clarke
>   
Brooke

The answer depends on how much heat has to be pumped.

Peltier heat pumps are quite effective as long as the amount of heat to
be pumped is relatively small.
With a 70W module a water cooled or blown heatsink is advisable.
With a 1W module an aircooled heatsink is adequate.
Small Peltier heatpump have been used to stabilise the temperature of 
photodiodes etc (HP used them in the 8153 light wave multimeter optical
detector heads).
They have also been successfully used to stabilise the temperature of a
baseplate with devices dissipating 10W or so attached to the baseplate.
Peltier modules are also used in small aerogel insulated refrigerators
and in drink coolers.

One potential problem is that low power peltier modules are very small
so that a high thermal conductivity heat spreader is desirable to
improve the temperature uniformity.
Single stage peltier modules are quite thin so that a thick low thermal
resistance heat-spreader/spacer is required to allow a sufficiently
thick layer on insulation to be used.

Bruce