This timer, like the previous circuits, uses a currently uncommon integrated circuit. The time is given by capacitor C1 and R2 which has the range of values indicated in the diagram.
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...