Univer df series led magnetic amp electronic proximity sensor switches univer df 220 this sensor can be mounted onto a univer pneumatic cylinder to detect the position of the piston it works by detecting the magnetic field produced by the magnet incorporated in the piston the sensor can then be used to switch an electrical circuit eg a safety interlock or warning signal or to energise the next component in a sequence this model employs an electromechanical reed switch and can be emplo