Hi Depends very much on what sort of environment it’s in ….
Bob > On Dec 21, 2020, at 9:03 PM, Dana Whitlow <[email protected]> wrote: > > A properly-tuned PID system does not cycle! > > Dana > > > On Mon, Dec 21, 2020 at 6:49 PM Bob kb8tq <[email protected]> wrote: > >> Hi >> >> Finding a data sheet on a TEC that goes past *very* basic stuff is >> essentially >> impossible. The bottom line is that the people who make them very much >> want to sell them to you. Finding information in those data sheets that >> suggest >> problems … not so much. >> >> The problem is (mainly) physical. The expansion / contraction of the >> device is >> a big deal. KHz level PWM is (likely) not a problem. Aggressive cycling >> from >> something like a PID is indeed an issue. >> >> Bob >> >>> On Dec 21, 2020, at 6:43 PM, Hal Murray <[email protected]> wrote: >>> >>> [Old mail, context is TECs] >>> >>> [email protected] said: >>>> If the drive current ripple is too high fatigue failure from cyclic >>>> thermomechanical stress can be significant. >>> >>> Do good data sheets say anything about that? >>> >>> Is there a frequency term in there? Can I use PWM, which is as much >> ripple as >>> you can get, as long as the frequency is high enough? If yes, ballpark >> of how >>> high? >>> >>> Physically, where is the heat/cold generated? Is it mostly at the >> junction? >>> >>> -- >>> These are my opinions. I hate spam. >>> >>> >>> >>> >>> _______________________________________________ >>> 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. >> > _______________________________________________ > 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.
