This circuit triggers a relay when a light beam that hits the phototransistor is cut off. The circuit is from Electronics Now and the supply voltage depends on the relay voltage.
Found in documentation from the 1970s, this circuit uses an oscillator and a display to warn of...
This circuit simulates a low-level siren and can be supplied with voltages from 5 to 15 V....
The filter shown in the figure, using only an operational amplifier, is characterized by allowing 1...