Digital timer with time-keeping measuring system - uses optical element receiving internal oscillator signal and photodetector

摘要

The digital electronic timer or timing relay has a time-keeping device which holds a fixed relationship to the frequency of an internal oscillator. The oscillator frequency controls an optical element, with an optical coupling between this element and a photodetector coupled to a measuring head (16), for supplying the frequency to the measuring head. Pref. the oscillator frequency is supplied via an AND gate (7) to an LED (9) and the signal is coupled to the measuring head (16) via a phototransistor (10) connected via a conversion circuit to a display (14), for indicating the time-keeping.