The trick is you use the TE devices at near zero delta-T. They will pump much more heat and dissipate little power.
-John =============== > Hi > > THe problem with cooler chips is that the heat still has to go somewhere. > On the "other side" of the device you need to deal with both the original > 10 or 20 watts plus the heat from the cooler. To move 10 or 20 watts and > get a significant delta T you need a pretty big cooler chip. Since they > are low voltage, that gets you right back to lots of current and thus > magnetic fields. > > The idea of putting the cooler a distance from the cell and coupling with > moving air is still an option though. > > Bob > > > On Dec 24, 2009, at 9:28 AM, Steve Rooke wrote: > >> I wonder how peltier devices would work for this application. Coupled >> with a temperature feedback servo they could be used to heat/cool the >> rubidium. Does anyone know if they have any electromagnetic field >> issues with them, the ones I have seen seem to be completely enclosed >> in aluminium which should act as a Faraday cage. They have the >> potential of providing a large thermal transfer capability compared >> with passive devices. >> >> 73, >> Steve >> >> 2009/12/25 Joe Gwinn <[email protected]>: >>> At 10:06 PM +0000 12/23/09, [email protected] wrote: >>>> >>>> Date: Thu, 24 Dec 2009 09:46:13 +1300 >>>> From: Bruce Griffiths <[email protected]> >>>> Subject: Re: [time-nuts] Cheap Rubidium >>>> To: Discussion of precise time and frequency measurement >>>> <[email protected]> >>>> >>>> Joe Gwinn wrote: >>>>>> >>>>>> Date: Thu, 24 Dec 2009 08:57:42 +1300 >>>>>> From: Bruce Griffiths <[email protected]> >>>>>> Subject: Re: [time-nuts] Cheap Rubidium >>>>>> To: Discussion of precise time and frequency measurement >>>> >>>> >> <[email protected]> >>>>>> >>> >>> [snip] >>> >>>>> >> Distributed heating using wire wound or printed heaters perhaps, >>>>> but >>>>> to >>>>>>> >>>>>>> reduce the associated magnetic field bifilar winding should be >>>>>>> considered. >>>>>> >>>>>> Non-inductive power resistors, which are commercially available, >>>>>> have >>>>>> very low magnetic fields. >>>>>> >>>>>> The low-inductance resistors have Ayrton-Perry windings, which are >>>>>> bifilar. >>>> >>>> No, Ayrton-Perry windings arent bifilar. >>>> >>>> Classically a flattened helical winding was made on a insulating card. >>>> An identical winding was then wound in the opposite direction on top >>>> of >>>> the first winding and the 2 were connected in parallel. >>>> The idea being that the small magnetic field produced by one flattened >>>> helix is cancelled by that of the other flattened helix. >>> >>> True enough - while there are two conductors, they are not close and >>> parallel. >>> >>> Anyway, the point is that non-inductive components by definition have >>> low >>> magnetic fields, and that non-inductive power resistors are common. >>> >>> To eliminate the field from the loop of resistors, one can have a >>> linear >>> string of A-P resistors in series, with a pair of return wires in >>> parallel, >>> with the return wires on either side of the resistor string, thus >>> reducing >>> the effective loop area. >>> >>> Joe >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> >> >> -- >> Steve Rooke - ZL3TUV & G8KVD >> A man with one clock knows what time it is; >> A man with two clocks is never quite sure. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
