This circuit was found in the July 1986 issue of Radio Electronics magazine. The circuit has a loudspeaker warning system. The sensor is the ceramic capacitor C1 which acts as a transmission line.
This circuit, from a 2002 documentation, checks the logic levels of the inputs, providing a...
Using a dual 555 CMOS this very useful circuit on the bench was found in the July 1998 Electronics Now...
The integrated circuit used in this regulator is quite old. Its 1970s casing is still made of...