Found in American documentation from the 90s, this circuit can be applied to other operational ones. We found it in an EDN of the time. Next to the diagram is the response curve.
The frequency of the sound emitted by this circuit depends on the light intensity on the sensor....
This circuit is from a thyristor manual from On Semiconductor. It makes use of a PUT and a SCR...
This circuit uses only one NC75Z04 port from ON Semiconductor, but it can be implemented with...