GB1163701A - Improvements in or relating to Electric Circuit Arrangements. - Google Patents

Abstract

1,163,701. Automatic exchange systems. SIEMENS A.G. 3 Jan., 1968 [4 Jan., 1967], No. 356/68. Heading H4K. In a system for signalling the identity of a satellite subscriber (calling or called) between the satellite and its parent exchange, the satellite and the exchange are each provided with a chain of bi-stable relays which are successively pulled-up by alternate positive and negative pulses, each relay having an auxiliary relay which is only brought up when a pulse of similar polarity to that which operates its main relay occurs immediately following such operation. The operation of the auxiliary relay and the interruption of the counting chain are controlled by a bi-stable circuit which is set and reset by the pulses of alternate polarity. As shown, the relay chain KS1 at the satellite is linked by a 2-wire line a, b to a similar chain KS2 at the exchange, a sinusoidal or rectangular wave generator U being included in series with the a wire. With the chains in the positions shown, viz. relays K5, K6 and E5, E6 operated, a positive pulse from U causes, in KS1; K5 to fall-back (release winding K5II); K1 to come up (operate winding K1I); bi-stable circuit T1 (in fact another bi-stable relay) to set to its 1 state (i.e. contact t1 at its "1" side): and in KS2; E5 to fall-back; E1 to come up; T2 to be set. The next following negative pulse releases K6 and E6, brings up K2 and E2, and resets T1 and T2. Succeeding positive and negative pulses step the chains on in similar manner. If contact a4 is closed (by a not shown winding of relay A4) in order to signal the identity of a wanted subscriber to the satellite, then the occurrence of the fifth pulse (which is positive) releases K3 and E3, brings up K5 but not E5, and sets T1 and T2. The following (negative) pulse is ineffective since none of the contacts e1, e3, e5 is closed. The next following positive pulse brings up S4 (K3, K5 and T remaining down, up and set respectively) and E5. In view of the latter the next negative pulse then causes the chain to step-on as before. The release of A4 and S4 is not discussed. In an alternative embodiment (Fig. 2, not shown), the chains consist of bipolar relays and the incoming pulses are stored on capacitors before being used to operate the chain and auxiliary relays. The operation of the relays is effected by discharging the capacitors into a transistor and transformer arrangement. It is essential to ensure that a pulse which operates a chain relay and sets a bi-stable circuit does not accidently operate an auxiliary relay. In Fig. 1 this is ensured by capacitors C1, C2 which delay the operation of T1, T2 until the amplitude of the pulse has decayed below an operational value. In Fig. 2, it is ensured by the provision of the capacitors and transistor discharge circuits in the counter chains themselves and also by the provision of another transistor/capacitor arrangement in the line. In the second embodiment, the generator U is made common to a plurality of satellite/ exchange links.