Patent GB-363696-A (GB)
Title: Improvements in electrical signalling and operating circuits
IPC: H04Q1/442
Filed: 1930-06-21
Abstract: 363,696. Electric signalling systems. TELEFONAKTIEBOLAGET L. M. ERICSSON, 33, Kungsgatan, Stockholm. June 21, 1930, No. 18986. Convention date, June 21, 1929. [Class 40 (i).] Alternating current in conjunction with rectifiers is used for signalling numbers or for controlling a power-driven switch over a two-wire line. Three arrangements are described. Power-driven selector, Fig. 1. The register controller completes the fundamental circuit through an alternating current source energizing STR via rectifiers L1, LI to start the selector which intermittently connects up the rectifier L2 to control the outstepping relay BIR. When the register is counted out, rectifier L1 is cut off, releasing STR which cuts the holding relay HOR into the fundamental circuit. Number indicator with selector-type registers, Figs. 2 and 3. Before the number is keyed, the wires a, b are bridged at the distant point, and all the receiving relays R1 .. R4, therefore are energized and S1 drives the step-by-step sequence switch Re6 off-normal. The odd positions are not stopping positions and the switch waits in position 2 for the keying of the first digit. This consists in separating the line wires and connecting to them ground direct or over rectifiers in any of the ways shown in Fig. 3 and results in the energization of only some of the receiving relays. S1 therefore falls completing circuit 22 for driving the first of the registers Rel .. Re5 off normal and energizing S2 which drives the sequence switch to its next (4th) terminals. The register, however, continues its advance owing to the action of self-interrupting contacts (not shown) to a point determined by the setting of the receiving relays. When the distant key is released, all the receiving relays pull up followed by S1 which causes the sequence switch to move to its sixth terminals in readiness for the second digit which is recorded on Re2. The positions of the registers are indicated on lamps 35, &c. Number indicator with relay registers, Figs. 4 and 5. In this system the use of a ground at the controlling point is avoided by causing some of the keys to make several circuit changes in succession. Normally the relays A, B and therefore relay F are energized, but the depression of any key releases at least one of them causing G to pull up and energize J. If both are released together, E pulls up and connects C, D to line in place of A, B. The condition of the relays for various digits is shown in Fig. 5, a + sign indicating the energized and a - sign the deenergized condition. Where both signs appear in a single square the lower one indicates the final condition of the relay. The setting is recorded on storage groups N .. R. On the release of the first key depressed, C, D, if not already operated, pull up and release E and A, B pull up releasing G which energizes K, leaving J locked up over its upper winding. K energizes L to connect up the next register. When next a key is pressed, G pulls up and shunts out J so that when the key is released, H pulls up and energizes M to connect up the next register. The registers may be restored by shortcircuiting H.