16 KHz telephone metering pulses supply circuitry - uses transistor of opto-coupler followed by monoflop transistor to derive pulses from exchange meter to operate tariff meter at calling subscriber's appts.

摘要

The circuitry feeding 16 kHz rated charge pulses to subscriber lines (T1n-A1) includes a controlled a.c. voltage amplifier (V) connected on the input side, via a coupling capacitor (C1), to a central a.c. voltage generator (G) and, on the output (load-) side, inductively via a bandpass filter (BP) to a subscriber line (T1n-A1), which includes a network-side 16kH3 blocking circuit (BSp). The rated charge count pulses are scanned by a scanning circuit formed by the four-pole network protection diode (D4), the current limiting and response threshold resistor (R6) and the optocoupler (OK) diode bridged by a response delay capacitor (C3). ADVANTAGE - Suitable for any type of telephone exchange including older models and plan numbers.