Generator for acoustic signals in telephone subscriber stations - has two multivibrators with different frequencies which are made alternately operative by third multivibrator

摘要

In the telephone subscriber station, on acoustic piezoelectric transducer (Pz) is used, connected between the rectified input and multivibrators. Two of the multivibrators (K1, K2) have specified but different frequencies (f1, f2) made alternately operative at an adjustable frequency (f3) by a third multivibrator (K3). Outputs of the two first multivibrators (K1, K2) are connected to a control transistor element (T1) by which the piezoelectric transducer (Pz) is charged and discharged in the rhythm of the two frequencies (f1, f2).