Hi If you do go the TEC route, plan on a fairly big power source :). There is a Wenzel doc on doing a TEC based enclosure using a couple of die cast boxes. The pictures don’t show what they used to drive the beast so part of it would still be up to you. My search skills and their web site are not quite compatible so no link …. sorry !!!
Bob > On Jul 12, 2019, at 12:12 PM, Javier Herrero <[email protected]> wrote: > > Hello, > > A TEC is good if you want to maintain the resistors at 25ºC, that seems the > zero TC point for some precision low TCR resistors (for example, the Vishay > VFCP or VSMP series) > > Regards, > > Javier > > On 12/7/19 10:06, Dr. David Kirkby wrote: >> On Fri, 12 Jul 2019 at 08:07, Bernd Neubig <[email protected]> wrote: >> >>> AXTAL has a miniature oven for heating precision resistors or other >>> components to a constant temperature. It is housed in a small DIP8 package. >>> See attached AXR135 data sheet. >>> Optionally this device can be offered unsealed, ready for inserting the >>> component by yourself >>> >>> Regards >>> Bernd >> >> The resistors I am using are made by Caddock, are 1 M ohm & 10 M ohm, 0.01% >> tolerance and 5 ppm / deg C. They are much too large to fit in a DIP8 >> package. A quick check with a ruler indicates that the 10 M ohm is 38 x 12 >> mm and the 1 M ohm is 19 x 10 mm. >> >> A quick photograph shows this half finished project. Unfortunately, even >> before I have finished it, I am wishing I had done a better job. However, >> my original reason for doing this was to check the stability of a data >> acquisition unit before sending it to Keysight. I think this will be good >> enough for that, but I could certainly have done a job with some thought. >> >> The thermocouple is just meant to be a temperature sensor that dissipates >> no power. A thermistor or RTD buried in the polystyrene would have just got >> hot. The resistors should not get hot, as the power dissipated will be >> under 1 uW. >> >> I also intend putting in a 100 M ohm resistor, but the specification of >> that is much poorer (5%, 100 ppm/ deg C. ) >> >> I partially read the paper mentioned. I note that the authors used a thermo >> electric cooler (TEC) as they wanted get low temperatures. I assume that >> for crystals or resistors dissipating little heat, a TEC would be >> unnecessary, and just a resistor acting as a heater would be fine. But will >> read some of the references. Obviously for controlling a crystal >> oscillator, or my resistor, stability is most important, whereas for the >> authors of the paper, stability was not their major concern. >> >>> -- >> Dr. David Kirkby, >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > -- > --------------------------------------------------------------------------------- > Javier Herrero > Chief Technology Officer EMAIL: > [email protected] > HV Sistemas S.L. PHONE: +34 949 336 > 806 > Teide 4, Núcleo 1 Of. 0.1 FAX: +34 949 336 > 792 > 28703 San Sebastián de los Reyes - Madrid - Spain WEB: > http://www.hvsistemas.com > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
