[volt-nuts] DIY Air bath

[Randy Scott]

>>>Actually the major trouble with Peltier is controlling them, because
>>>they are asymetric with respect to transport direction.
>>
>>I think the negative feedback of the control loop helps with that,
>>unless the difference is so big that it requires different
>>compensation for cooling and heating to be stable.
>
>Depends on the temperature difference but I seem to recall that it
>is something like 1:3.

Forgive my ignorance, but does this mean that it is "harder" to cool
than it is to heat, given the same magnitude of current through the
junction?


>The problem is that once you get to your target temperature, it will
>fuddle around with the small residual noise and because of the
>asymetry it actually amplifies the noise if you don't do something
>to prevent it.

Does this depend on the manner in which you're driving the Peltier
(a "digital" control where the junction is fully-heating, fully-
cooling, or off vs. an "analog" control where the control loop
controls the magnitude and direction of current flow)?

Randy.