[time-nuts] SMPS or conventional?

[Dana Whitlow]

A properly-tuned PID system does not cycle!

Dana


On Mon, Dec 21, 2020 at 6:49 PM Bob kb8tq <kb8tq at n1k.org> 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 <hmurray at megapathdsl.net> wrote:
> >
> > [Old mail, context is TECs]
> >
> > bruce.griffiths at xtra.co.nz 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.
> >
> >
> >
> >
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