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 small audio amplifier circuit in complementary symmetry was found in the 1974 Mullard...
Adders appear several times on this site with operators of all types. In this circuit the output...
This circuit was found in the October 1993 Electronics Now magazine. The circuit can be used in a...