This dual-LED circuit indicates three signal levels. It was found in the January 1996 issue of Electronics Now magazine. The integrated circuit may be an LM339 or another comparator.
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...