This small tube amplifier appeared in Radio Electronics magazine in February 1958. The circuit is powered by the mains with a power transformer and output with different impedances.
This circuit was obtained in a 1973s documentation. The transistors may be BC558 for the PNP and...
The sensors in this circuit that triggers when the temperature goes out of a certain range are...
Other operational amplifiers series, such as MC34072, MC34074, MC35071, MC35072, MC35074 d MC33071...