This circuit was found in a Popular Electronics from the 90s. The circuit has 4 frequency ranges selected according to the capacitors. Signal is rectangular.
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...