This QST circuit generates 4 frequency signals according to the crystals used. Transistors admit equivalents although the indicated types can still be found with some ease.
Found in American documentation from the 90s, this CMOS circuit detects the source of a signal and can...
I found this circuit in an old English magazine from 1981, but it can still be assembled with some...
This circuit was obtained from a 1969 Electronic Design. Transistors admit modern equivalents. The frequency...