SUBSCRIBER INTERFACE UNIT

摘要

The multi-meter connecting device of a subscriber interface unit comprises: a switch transistor having a base terminal connected to a pulse control terminal of a central processing unit via a resistor; a plurality of reverse current preventing diodes connected in parallel to the collector terminal of the switch transistor; a plurality of switches respectively connected to the diodes; a high frequency noise removing low pass filter connected to the switches; and a plurality of triggers having an input terminal connected to a resistor connected to a power source and to the low pass filter and an output terminal connected to the pulse input terminal of the central processing unit.