This circuit mimics the trill of a bird. We found it in an American documentation from the 90s. It is based on the LM3909 integrated circuits.
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...