[time-nuts] SMPS or conventional?

[Bob kb8tq]

Hi

Depends very much on what sort of environment it’s in ….

Bob

> On Dec 21, 2020, at 9:03 PM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> 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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