This circuit has an accuracy of 1%. The components used must be precision as well. The input frequency range is 40 Hz to 10 kHz with the indicated components.
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...