Found in a 1990s US publication, this alarm circuit detects when a light beam is interrupted. Optical resources may be used for the sensor and instead of the alarm a relay may be used.
NI has announced the release of Multisim 14, our industry-standard SPICE simulation environment....
The circuit in the figure represents a typical application of a phototransistor exciting a relay...
With this circuit, power cables can be detected by simply approaching PP. PP is an antenna or...