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 amplifier with high input impedance was suggested by National Semiconductor in its 1994...
This circuit synthesizes the tick of a metronome with the speed controlled in RV1. The circuit is...
This circuit makes use of an unusual component which is a large surface diode that can be used to...