This basic CMOS 4001 circuit was found in the April 1976 issue of Radio Electronics magazine. The circuit generates rectangular signals, and the components can be changed to obtain other frequencies.
Settings like this can be found in this section and on this website, but from different sources of...
This circuit with TTL output was found in a 1968 EEE. The transistor can be of general use. The...
Found in a 1980s manufacturer documentation, this circuit can be used as an optical shield. The...