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" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <time-nuts@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: [EMAIL PROTECTED] 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 <[EMAIL PROTECTED]> > 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: [EMAIL PROTECTED] 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@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 > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.