With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of the 555. The circuit was found in the November 1989 Radio Electronics magazine.
This second-order filter was found in a documentation from the 90's. It can be implemented with...
To implement this function, we need a relay with double contacts, as shown in the figure. With a...
In this circuit the relay triggers on when light falls onto the sensor, a common LDR. Power supply...