This infrared alarm barrier can be used to detect persons passing through doorways, corridors and small gates. The transmitter emits a beam of infrared light which is invisible to the human eye. The ...

Accurate tower light monitoring is a serious matter, and great care can be taken to install a thorough and automatic monitoring system. Designing a system to provide a single-lamp failure can quickly ...

The receiver circuit in Figure 1 sounds an audio alarm when the transmitter (Figure 2) moves beyond a designated perimeter. The transmitter, a voltage-controlled ...