Found in a 90s American documentation, this circuit uses an integrated from the time that is difficult to obtain today. The sensor is a common photodiode.
A first circuit that uses a phototransistor as a detector and is suitable for covering short...
We found this circuit in recent English documentation. The circuit uses CMOS technology and can be...
We found this circuit in an old Mullard (Philips) documentation on the 555 and 556 integrated circuit...