Patent GB-1072762-A (GB)
Title: Improvements in or relating to electric circuit arrangements
IPC: H04Q3/00
Filed: 1965-04-23
Abstract: 1,072,762. Controlled non-linear inductors, automatic exchange systems. SIEMENS A.G. April 23, 1965 [April 24, 1964], No. 17169/65. Headings H3B and H4K. A saturable magnetic core M having an approximately rectangular hysteresis loop has a line winding We connected in a telecommunication line circuit L; an output winding Ws associated with a line relay K, and a control winding Wa energized by bipolar pulses, A.C. signals being induced in the output winding except when the core is saturated by line winding current. In Fig. 1 (not shown) the relay is connected to the output winding through a rectifier bridge Gs1-Gs4, whereas in Fig. 2 rectification is provided by two oppositelywound output windings Ws1, Ws2 each in series with a respective half-wave rectifier Gs1, Gs2. A transistor T and a half-wave rectifier are provided in Fig. 3 (not shown) for the output winding circuit, the relay K being in parallel with an R-C. circuit serving both for holding and spark quenching. In these arrangements the relay is normally operated and falls back when line current is present. Figs. 5 and 6 (not shown) are similar to Figs. 3 and 2 respectively, but have the output winding transistor circuits arranged so that the relay is normally released. Slow operating and release characteristics are obtained in Fig. 9 (not shown) by the use of two opposed and parallel line windings one of which is in series with an R-C. circuit. Rapid operation and release are obtained in Fig. 10 (not shown) in a circuit including a line inductor Dr, an additional winding II on the inductor being connected in series with an additional winding We2. A line circuit for D.C. signals with superimposed A.C. signals for an alarm W is described, Fig. 12 (not shown), the line being connected in series with two parallel and opposed line windings Wel, We2. A capacitor C1 is connected in one parallel branch so that D.C. passes through one branch only and switches the relay, while A.C. passes through both branches and is without effects. In Fig. 14 (not shown) a line loop has both conductors connected to respective line windings Wel, We2. Two cores M1, M2 and respective relays A, E are used in Fig. 15 (not shown), the circuit of relay A being connected to an additional winding We2 on core M2, and the line circuit having one conductor 1 connected to a .line winding We1 on core M1, and the other conductor 2 connected in series with line windings Wel, We2 each on a different core. Interruptions in the loop by a contact S operates relay A, while actuating an earthing key ET actuates relay E. In a modification of Fig. 15, Fig. 16 (not shown), relay A is operated by interruptions in the loop, while relays A and E both operate if ET is actuated. Fig. 13 (not shown) discloses an arrangement for A.C. line current, the line circuit including a rectifier bridge G1 connected to the line winding We. An arrangement of three cores M1-M3 with respective relays S1-S3 is disclosed, Fig. 17 (not shown), in which each core is differently biased by windings Wv and the relays selectively respond to three different levels of line current. In a modification, Fig. 19 (not shown), the bias windings are energized from the control winding pulse source.