Test equipment for checking circuit connection - between telephone caller and receiver inject AC signal into coupling field current measurements as check

摘要

A circuit testing unit enables the connection between a telephone caller and receiver over a coupling field to be checked for malfunction. The caller (TN) is connected over various stages (KSA, KSB ... KSN) in a coupling field (KF) with the receiver (VS). The test unit (PG) consists of a transmitter (UE), the primary winding of which is connected to an A.C. supply generated a test signal (Um). The secondary winding is then connected to the appropriate lines in the coupling field and the current (12) is measured by an A.C. meter (M2). The secondary winding is also connected to a D.C. source (GQ) and the current measured (M1). A valid check on the circuit connection is dependent upon the relative values of the two meter readings.