[volt-nuts] DIY Air bath

[Will]

Varying room temperature is a remarkable source of error when making
measurements in home environment. It would be nice to have a simple
air bath for the items under test. And even better if it was big
enough for the multimeter too. There are commercial units available
but very expensive.

A DIY solution seems to be possible: a simple PI(D) controller built
around an NTC resistor, op-amp, pass-transistor and heater plus a fan
to keep the air moving inside the box. That approach allows
temperature higher than room temperature only but in most cases
stability is important and not the absolute value. A Peltier element
is almost as easy to drive as a heater resistor, but dissipated heat
probably makes the thermal design much more challenging.

I am not an expert and there many questionmarks related air
circulation, thermistor location and probably other things I can't
even imagine.

Will