[time-nuts] Improving the stability of crystal oscillators
jgd at johngsbbq.com
Sat Oct 13 18:19:57 EDT 2007
Nah, not for this application. A Peltier module typically has a COP of 1. That is,
it moves a watt of energy for each watt consumed. Thus, for each watt moved, two
watts have to be dissipated to air.
I can't imagine a well-insulated quartz oscillator needing more than a watt or two of
cooling at the most. A heat sink capable of handling 4-5 watts should do the job
Don: I've seen peltier-controlled "ambient" ovens before but I can't recall the
details. I'm fairly sure one was a Fluke precision voltage transfer standard in
which the zener reference diode was controlled to a constant temperature.
The advantage of using room temperature, e.g., 70 deg F, is that under most
conditions, the peltier module is doing little to nothing, perhaps just ridding the
ovenized unit of the few milliwatts dissipated in the circuit itself.
I've used multiple cascaded modules to cool a nuclear detector (Silicon surface
barrier diode) to reduce its noise. Not as good as LN2 but much cheaper to operate.
On Sat, 13 Oct 2007 13:26:52 -0700, Brooke Clarke <brooke at pacific.net> wrote:
>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.
>Don Collie wrote:
>> ); SAEximRunCond expanded to false
>> Errors-To: time-nuts-bounces+brooke=pacific.net at febo.com RETRY
>> Has anyone concidered using a small Peltier pile to maintain the crystal`s
>> temparature. I understand that these devices will heat or cool, so it would
>> be possible to maintain the crystal temparature at , say, 25 degrees
>> celcius, over a range of ambient temparatures
>> [perhaps 0 to 70 degrees]. There would be several advantages in this
John De Armond
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