This 4-tube counter was found in Radio Electronics magazine from December 1959. The circuit uses a coil as a sensor to detect the passage of metallic parts or magnets.
This circuit has been obtained from a technical documentation on filters from 1977. The...
Figure Bellow shows how to use a 7490 (TTL) IC to divide the frequency of a TTL signal by 6; The...
Found in a 1969 Burr-Brown publication, this circuit makes use of integrated components from that...