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 was obtained in the Motorola Linear Interface ICs of 1993. The current is determined by the...
This circuit was obtained from a Linear Technology manual from the 1990s. The components may have...
This configuration can be found in several articles on this site. The one shown in the diagram is from...