This alarm with automatic shutoff was found in the April 1975 Radio Electronics magazine. The activation time is given by C1 and R3. The alarm uses series and parallel sensors.
This circuit used in tape recorders was found in an Electronic Design. The components support...
This circuit uses common components activating a control relay for the water pumps. The sensors are...
The two adding and differentiating circuits with operational amplifiers given below were obtained from...