This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are general-purpose types. The circuit triggers when the light that falls on the sensor is cut off.
This circuit was obtained in a Electronics World of 1968. The transistors can be equivalent as the BC558...
This 1967 General Electric circuit makes use of an array of 3 (integrated) transistors for an...
This converter has coils according to the reception and converted frequency bands. We found it in...