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 is a basic astable circuit using the 555 IC and driving two LEDs. The phase on a rate giving...
More inputs can be added to this adder that we found in the January 1995 Electronics Now magazine....
This circuit converts a high impedance signal into low impedance. The circuit has unit gain and...