The sensors in this circuit that triggers when the temperature goes out of a certain range are common diodes. The circuit is from the 1991 Reista Electronics Experimenter's Handbook.
Other operational amplifiers series, such as the MC34072, MC34074, MC35071, MC35072, MC35074 or...
This circuit with the HA2400 was found in the March 1980 Radio Electronics magazine. The circuit has...
This circuit has two high-impedance inputs. The gain is high and more inputs can be added. Use a...