[time-nuts] SMPS or conventional?

[Bob kb8tq]

Hi

I must admit, the longevity of the compressor based setup in the typical kitchen 
fridge continues to amaze me. :). 

=======

TEC’s have a fairly limited “pumping range”. It is not uncommon to discover you
need to stack them to get this or that job done. We wound up with a stack of
5 to get one project working. 

In some designs the TEC / stack never does anything other than run at X current. 
If the goal is “take care of an Rb out in the (-10 to +45C) garage”, it’s going to see 
a lot of cycles …

Fun !!

Bob

> On Oct 23, 2020, at 6:29 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> 
> --------
> 
>> TEC’s are indeed prone to wear out. That said, so is a compressor …..
> 
> The mechanism is almost entirely mechanical and running a TEC at a
> stable current almost 100% mitigates it.
> 
> The surefire way to force the wearout is to reverse the current
> direction a lot.
> 
> Whatever you use to control the TEC, needs to understand that there
> is a 1:3 efficiency difference between the two directions, just
> slapping a PI(D) on a TEC is guaranteed to kill it.
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by incompetence.