[time-nuts] Improving the stability of crystal oscillators

[Don Collie]

Thanks for that John. I`ve always wanted to play arround with one of these 
[Peltier] modules. They can now be bought quite cheaply. I envisage a double 
oven, with the inner oven heated [to 25 degrees], by conventional means, 
while the Peltier pile cools the inner oven. This way you could use
a precision temparature regulator for the inner oven, while the outer "oven" 
would only have to cool. You wouldn`t be talking too many pumped watts, 
here.
FWIW etc.,.......................................Don C.


----- Original Message ----- 
From: "Neon John" <jgd at johngsbbq.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Sunday, October 14, 2007 11:19 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
>
> 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
> just fine.
>
> 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.
>
> John
>
> On Sat, 13 Oct 2007 13:26:52 -0700, Brooke Clarke <brooke at pacific.net> 
> 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.
>
>>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
>>> approach.
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Tellico Plains, Occupied TN
> I like you ... you remind me of me when I was young and stupid.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.488 / Virus Database: 269.14.9/1069 - Release Date: 
> 10/13/2007 7:26 PM
>