... 5/6 LED Frequency Meter (FA) Features:1, Input: various wave form pulse signal(proximity switch,photoelectrical switch or AC signal,etc),contact switch ... to equipment for control of frequency,tacho,line-speed,level,etc;The instrument has several parameters setting function,easy ... duty cycle,etc,please indicate when ordering.3, 4/5/6 digit display,with demical point switched automatically;Opical ...