Time measuring pulse circuit - with pulse selector passing time dependent frequency pulses from pulse generator to counter

摘要

A time counter for use in determining the duration of telephone calls can be produced at a reasonable cost, suitable both to measure short times with small absolute tolerances as well as long times. The pulse generator PG passes several separate pulses P1 to Pn of different frequency to the counter Z. A pulse selector circuit PA is inserted between pulse generator and counter to pass, as a function of time, only a pulse of a certain frequency to the counter so that the count rate of the counter becomes a function of the time. This makes it possible to load the counter with fast pulses when the time to be measured is short, and to feed pulses with a slower frequency during longer times to be measured.