We found this circuit in an American publication from the 90s. It generates pulses that can be modulated in amplitude. The supply can be done by voltages from 5 to 12 V and the frequency depends on C1 and C2.
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...