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.
Found in old documentation for radio amateurs, this circuit is intended to excite a MOSFET on the...
This silencer or squelch preamp circuit was found in a documentation for radio amateurs. It...
This Siliconix circuit was found in a 1980s documentation. The coil consists of 18 turns of 22...