This circuit for communications receivers was found in the January 1974 issue of Radio Electronics magazine. The transistors are Japanese types of the time, as the circuit was part of equipment of that origin.
By connecting several photocells in series, we can directly activate a sensitive relay, as shown in...
We found this simple IF circuit in a book from the 50's. The transistor is made of germanium and...
This circuit was found in the February 1992 issue of Radio Electronics magazine. The circuit...