This simple audio and RF signal tracker was found in a Japanese publication in 1967. The transistors are made of germanium and the headphone is made of crystal.
This RS flip-flop uses two type 4N26 optical couplers and is characterized by the very high...
This flasher was found in an old Hands On, but uses common components. The optocoupler can be...
This circuit was obtained from a 1969 Electronic Design. Transistors admit modern equivalents. The frequency...