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 circuit provides both frequency and voltage division. The circuit was found in a 1966...
This circuit converts a signal from any waveform into a rectangular or square signal of the same...
Found in Unitrode documentation from the 1980s, this circuit makes use of PUTs, currently common...