Station start system

Abstract

Abstract PURPOSE:To improve the general-purpose property of a trunk line trunk by providing a polarity and call signal detecting circuit and a call signal control circuit in correspondence to the trunk line so as to connect the trunk line in both cases of the earth start system and the loop start system. CONSTITUTION:The polarity and call signal detecting circuit PRD is connected between terminals L1 and L2 of the trunk line trunk, a call signal from the trunk line is detected and the earth is given to a control circuit CTL2 via a gate G1. An output from the circuit CTL2 drives a relay driving circuit RDV via a call signal controlling circuit RCTL. Through the driving of the relay, a loop consisting of a choke coil RET and a loop current detecting circuit LD is formed between the terminals L1 and L2, making the call respond to the trunk line. The DC current from an exchange made busy with the circuit LD is detected to conrol the CTL2. When the PRD detects DC voltage, the trunk line adopts the loop start system and when DC current is not detected, the trunk line adopts the earth start system applying earth potential to lines.

Inventors

• 👤 Kazuhiro Sato
• 👤 和弘 佐藤

Bibliographic Details