Control system Today I am going to describe the control system executed on the gate in the building of the local government garage. It is composed of three main components: -the movement detector; -the sensor that can recognise car's numbers; -the barrier. When any car arrives in front the barrier, the movement detector detects movement and sends output current to the video sensor and logic gate. The video sensor gets the signal and automatically starts recognising the number of the car and comparing it with the allowed numbers in its memory. If they match, the sensor sends the output current to the logic gate. The logic gate produces an output current only if it receives both input currents (AND gate). Sometimes it doesn't work properly and CCTV is essential in this case. Video camera transmits the picture to the monitor of a security guard.