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.
This digitally programmed gain amplifier was obtained from Signetics documentation from the 1980s....
This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF...
This circuit was obtained from an American 1980s documentation. The frequency depends on the...