Found in American documentation from the 1990s, this circuit receives modulated infrared signals. The baud rate depends on the operative used. The main application is like audio link.
This circuit was taken from the 1974 Ferranti transistor manual. Note the shapes of the signals....
This mini siren, found in a 2003 publication, powers a small piezoelectric transducer, but a...
This fuzz effect is from a 1988 Italian publication, but it can be easily assembled, as the...