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 antenna for the frequencies 146 or 440 MHz was found in a magazine 73 for Amateur Radio of...
This circuit produces 1 kHz square signals using the CMOS IC 4070. The frequency is given by the...
Found in a 90s PE Hobbyst Handbook, this circuit mimics the sound of a space gun. The components...