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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 hot. Also, there is a correction to the schematic: The dual op amp is not a 1488, it's a 1458. |