A few days ago I put the whole control arrangement in a box
with some visual feedback and adjustment.
Also to save tripping over all of the wiring in the dark!
I got a 3.5 digit LED module from Jaycar and set it up to
measure 3 things via a 3 position switch on the front.
Excuse the rough Brother labeller titles on the front.
Pos 1 reads the 12V Battery that powers the Peltier.(Pic1)
Pos 2 reads the offset voltage (the temp adjustment)
(with a bit more refining this can be further op-amped/biased to read
a meaningful temp in °C)(Pic2)
Pos 3 reads the 5V regulator voltage (the LED module required 5V).
The 20 turn 1K potentiometer for fine temp control has been desoldered
and brought out to the front panel so adjustment is easier in the dark.
I would like to thank Peter_4059 for putting me on to this kit
from Jaycar. Peter, this circuit is doing exactly what I wanted it to
do. Cheers for the advice!
Steve