This circuit recognizes a tone determined by the tuned input circuit (R3 / R4 / C2). The circuit was found in Radio Electronics from the 90s. The 4046 is not a common component today.
This circuit was obtained in a 1982 English magazine. This circuit can be used both as a simple...
This sensor triggers an oscillator emitting sound when a magnet is approached by a reed switch....
Suggested by Burr Brown in 1969 documentation, this circuit makes use of an integrated component...