The SH 11 model scanning head was especially designed both for scanning of the marks on the rotating discs of mechanical meters or simulated disc marks on LCD displays and for detection of light emitting diodes (LED’s) of electronic meters. The choice of operation with mechanical or electronic meters is made by simple rotation of a selection switch. The precision optical lens is designed to make the scanning head insensible to external light. Its compact, robust construction makes the head equally suitable for use in stationary test consoles as well as for use with mobile and portable equipment. The impulse output of the scanning head delivers a positive output pulse of the duration 0.5 ms.