This circuit from a 1967 documentation generates 2.5 Hz signals depending on the capacitors used, in this case 160 uF. For 4 6700 pF the signal will be 20 kHz.
This simple trigger circuit was found in a 90’s American documentation. The integrated circuit is...
This sensitive circuit was found in the August 1971 issue of Radio Electronics magazine. The SCR...
The varactor or varicap diode tunes the signal for listening to SSB signals on a common receiver. The...