This photoelectric sensor that triggers a relay was found in an English book from 1989. The transistor is a general-purpose type, and the integrated circuit consists of an operational amplifier.
An stable multivibrator with 50% of duty cucle can be mounted using the 555 as shown by the...
This circuit was found in the old Mullard transistor reference manual from 1960. The circuit uses...
We found this circuit in a 1976 documentation. The transistor and the integrated circuit must have...