This TTL circuit was found in an American documentation from the 80s. The components are common in the series and the supply must be made with a voltage of 5 V.
This circuit can decode an audio tone whose frequency depends on R1 and C1. R1 can be in the range...
This is the basic configuration of an operational amplifier amplifying signals from a photo diode....
This regenerative circuit was found in a Japanese publication from the 1960s. Details of the coils...