Found in a 1980s telecommunications documentation, the circuit presented acts as a product detector. The modulator or mixer in the square may be that of the previous circuit.
This simple intercom for home use was found in a 1979 publication. It can be easily mounted with...
This circuit was obtained from American documentation from the 1990s. The transformer can be a car...
This wired intercom circuit was found in an English publication from the 80's. The integrated...