Based on the well-known LM3909, this LED pulser circuit was found in American documentation from the 90's. The power supply is only 1.5 V.
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...