Found in documentation from the 1980s, this circuit can generate signals between 6 and 8 MHz. The frequency can be slightly varied in the setting. FET is a general-purpose type.
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...