Tariff metering system for telecommunications apparatus - uses quartz-oscillator clock with digital display for switching between tariff rates

摘要

The quartz-oscillator clock is used to control the switching between different tariff rates, applicable at different times of the day etc., with a clock pulse generator, supplying the tariff metering pulses, having a corresponding number of clock pulse rates. For checking the latter, the clock pulses are supplied via a flip-flop to one input of a logic gate, and the other input of a logic gate, and the other input of the latter is supplied with count pulses from the mixer stage of the quartz clock. The output of the logic gate is connected to a counter and a digital display, for indicating the measured duration between pulses, can be switched from the clock, to the counter. The clock pulses may be supplied to the flip-flop via a Schmitt trigger.