This is the actual constructed model of schematic
0.06. Observe it
cooling the thermistor to the left. It will be
incorporated into the final product.
It is being run off a 12V 1A wall wart. It works
just fine, cooling in a controlled, linear fashion.
You can hear the fan change speeds slightly as
power feeding to the thermoelectric cooler changes,
but the 9V zener provides good enough regulation
for the analog parts of the circuit that the power
changes don't push it into oscillation or
make the output wiggle. Adding more heat causes it
to properly drive more power to compensate. The
resistors and power amp get warm, but not
Also, there is a correction to the schematic: The
dual op amp is not a 1488, it's a 1458.