GB475952A - Improvements in and relating to telephone systems - Google Patents

Abstract

475,952. Exchange systems. AUTOPHON AKT.-GES. Feb. 20, 1936, No. 5215. Void. Convention date, Feb. 20, 1935. [Class 40 (iv)] A local battery switchboard, such as a field switchboard, is associated with certain lines at the main frame of an automatic or other exchange by means of an auxiliary device comprising two position keys OB, Wand D, V, push-button keys M, drop indicators FKl and indicators SZ as shown in Fig. 3, so that they may communicate via the automatic apparatus if it is still working or via the local battery switchboard and so that lines connected to the local battery switchboard can be extended via the automatic apparatus. The auxiliary device is connected in by means of plugs of the type in common use for associating test apparatus. In a simplified arrangement, Fig. 2 (not shown), certain lines are automatically connected to the emergency switchboard when the exchange is destroyed. The description is imperfect. Circuit arrangements. (1) Calls originated by automatic subscriber. With the keys in the normal position as shown, the looping of the line Zt energizes A which energizes C. As a result, the indicator Sz is operated and an impulse is given over the wires zKS to operate one of the drop indicators in the local battery switchboard (not shown). The attendant may then (a) extend the call over the local battery switchboard or (b) operate the key D to give the subscriber control of the automatic switches in the ordinary way in which case the relapse of A, C puts the indicator Sz into the line to give supervisory signals to the operator of the auxiliary device who can also listen-in with the aid of the key M, or (c) operate the key to associate the dial AAG with the automatic exchange apparatus, establish a connection over such apparatus and hold it by throwing key V while the calling subscriber is recalled if necessary. (2) Calls originated by local battery sets connected to automatic exchange lines. In this case key OB is thrown and the line appears in the local battery switchboard in the ordinary way. The call can be extended over the automatic switches as described under 1 (c) above. (3) Calls originated by lines on the local battery switchboard are established over the automatic apparatus as described under (2) above. (4) Calls from the automatic apparatus operate the drop indicator FKL and can be extended by the key V to the line ZT, a further contact of V operating the ring-trip relay.