This indicator or logic probe was found in the April 1979 Radio Electronics magazine. The integrated circuit is the 555 and the FET can be any general-purpose type.
This source, found in a 1991 publication, was originally designed to operate with the CB18736E, an alarm...
We found this circuit in a publication of 1990. With the changes it can be mounted easily today....
This circuit mimics the sound of a siren when we turn the axis of the small DC motor. The...