This infrared light barrier kit can be used to perform various monitoring tasks, such as checking whether windows or doors are opened or closed, whether people are entering a room (access control), for scientific experiments and much more. The distance between transmitter and receiver can be up to 4 metres, depending on the orientation of the units. This means that even larger distances can be monitored and controlled. If the invisible light signal between RX (receiver) and TX (transmitter) is interrupted, a loud warning tone is immediately emitted. The IR light barrier was developed especially for indoor areas. Both boards can be operated with a 9 V block each (not included in the scope of delivery). Alternatively, a 9 V power supply unit can also be used as a power supply. The comprehensive and detailed instructions accompany the soldering process and enable even inexperienced users to assemble the IR light barrier.