22,596. Neuhold, E. April 7, [Convention date]. Automatic exchange systems. - Instead of controlling the actuating- magnets of the various selectors by means of relays associated with each selector, the selecting-impulses received from the sub-station are repeated to the actuating-magnets of the respective selectors by means of a single relay set associated with the first selector. In the system described no side switches are used, the necessary connexions between successive selectors being made by relays. The Figure shows two first selectors I, I<1> belonging to the subscribers A, B, together with the second selector II and a connector III. The sub-station impulse-transmitter is represented diagrammatically by the keys t<1>, t<2>, by which either line-wire can be earthed. First selector. If subscriber A wishes to call subscriber 5345, he first depresses the key t<1> five times, and then the key t<2> once. Current from the battery a thus flows through a winding r<4> of a differential relay r<3> to the earthed line 5, and the armature r<9> closes the circuit of a relay r<1> over the same earthed line 5. The five selecting-impulses sent by the key t<1> are thus repeated to the circuit of the vertical' magnet z of the selector, current flowing from the battery a through the armatures r<5>, r<6>, wire 35, armature i<2>, and through the magnet z to earth. The wipers b, c, d of the selector are thus raised to the fifth horizontal row, the movement of the switch opening the contact u to render the subscriber 'busy' to other calls. The depression of the key t<2> earths the line 6 and energizes the winding r<7> of the relay r<3>, and the relay r<2>, so that a single current-impulse passes over armatures r<5>, r<8>, i<1> to the rotary' magnet e, which rotates the switch one step. This initial movement of the selector closes the contacts p, q, thereby connecting the positive terminal of the battery through the interrupter s, contact p, and armature k' to the magnet e, whereby the selector is rotated until its wiper d engages the terminal of an idle second selector II, when a circuit is completed from the battery through the contact u of the second selector, wiper d, armature i<3> and the relay i to ground. The relay i locks-up over its armature k and contact q, at the same time (1) disconnecting at k<1> the relay e from the interrupter s, and (2) continuing the connexion of the wires 34, 35 through the armatures i<1>, i<2> and wipers b, c to the wires m, n. As the armatures r<6>, r<8> fall back after each selecting-impulse, they make a sliding contact with an earthed lead j, thereby short-circuiting the actuating-magnets z, e so as to prevent the 'extra' currents from these magnets passing into the relay or line circuits. Second selector. The next set of three impulses sent by the key t<1> are repeated by the relays, r', r<3> over the wires 34, m to the 'vertical' magnet z of the selector II, the wipers of which are raised, as before, to the third horizontal row. The subsequent earthing of the line 6 is similarly repeated over the wires 35, n to the 'rotary' magnet e, which rotates the selector one step, thereby closing the contact p and connecting the magnet e to the interrupter s so that the selector is rotated as before until its wiper d engages the contact of an idle connector III, thereby completing a circuit from the battery through the contact u of connector III, relay T, wiper d, and relay i of selector II. The relay i locks-up as before, disconnecting the interrupter s from the magnet e, and continuing the leads m, n over the wipers b, c to the connector. The relay T is also energized and locks-up over its earthed contact, so that the connector is at once rendered busy to other second selectors, even before its spindle has been raised. The second selectors may also be provided with relays similar to the relay T. Connector. The set of four impulses sent by the key t<1> are repeated by the relays r', r<3> over the wires 34, m, 11, to the vertical' magnet z of the connector III, the wipers of which are raised to the fourth row. The last set of five impulses sent by the key t<2> are similarly repeated over the wires 35, n, 12 to the 'rotary' magnet e, which moves the wipers on to the contact of the required line. If the desired subscriber is disengaged, a circuit is now completed from the negative pole of the battery, over the armature of the releasemagnet y of the called subscriber, relay R, contact u, test-lead 9, wiper d and relay i to earth. The relay i locks-up over contact q, disconnecting the magnets e, z, and continuing the leads m, n, and 11, 12 over the wipers b, c to the line-wires 7, 8 of the called subscriber. The relay R locks-up over its earthed contact, opening contact u so that the subscriber B is rendered busy to other calls. The subscriber A can now call subscriber B by meaus of a magneto bridged across his line-wires. Microphone current is supplied to both subscribers through the windings r<4>, r<7> of their differential relays r<3>, which are not energized at this stage. By the provision of an additional relay X in shunt -to the relay R, the circuit of the called subscriber's relay r<3> may be broken, so that microphone current is supplied only through the relay r<3> of the calling subscriber. The talking circuit between the subscribers passes from subscriber A through the lines 5, 6, retracted armatures r<6>, r<8>, wires 34, 35 ; m, n ; 11, 12 ; 7, 8 ; to the subscriber B. If the desired subscriber is engaged, the calling subscriber receives no answer, and proceeds to restore the connexion as described in the next paragraph. Release. At the end of a conversation, the calling subscriber depresses a key t<3>, thereby earthing the line 5 directly, and the line 6 through a resistance 14. The windings r<4>, r<7> are thus excited unequally, so that the relay is energized and completes the circuits of both the relays r<1>, r<2>, which in turn complete the release circuit from the battery a through the armatures r<10>, r<11>, resistance 36, to the release-magnet y of selector I and earth, and also in parallel over the contact i<3>, wiper d, and wire w to the release-magnets y of the second selector and connector. The selectors I, II and the connector are thus returned to their zero position. The contact u of the called subscriber is again closed when the relay R of the selector I<1> is de-energized, which is effected when the called subscriber energizes his release-magnet y by closing contact t<3>. If the connexions 37, 38 shown in dotted lines are provided, the contact u of the selector I<1> is returned to its normal position when the other selectors are released by the calling subscriber, the release-magnet y of this selector being then in parallel with the other releasemagnets. The connexions 37, 38 must be provided when the relays X, previously referred to, are used. A resistance 39 in the test-circuit w serves to prevent premature excitation of the release-magnet of the selector when the relay i has been energized and before the next selector has been raised. If the desired subscriber is engaged, the calling subscriber cannot restore the connector III in the above manner since the relay i of the connector has not brought its release-magnet y in parallel with the release-magnet of the selector II. The calling subscriber therefore repeatedly depresses his key t<2> so as to bring the wipers b, c, d on to the last set of contacts in the row, of which the contacts engaged by the wipers b, c are dead, but the third contact is connected directly to the battery a. The relay i is thus energized and locks-up, bring- iug the release-magnet y of the connector into parallel with the other release magnets, so that the depression of the key t<3> returns the connector as well as the selectors to normal.