Improvements in or relating to telephone systems

Abstract

Abstract 1,131,663. Dictation systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd. 28 July, 1967 [9 Aug., 1966], No. 35673/66. Heading H4K. In a private exchange in which a subscriber having access by dialling or otherwise to dictation equipment is provided with keys for controlling the operation thereof through the medium of a selective receiving circuit SRE, all the control signals consist primarily of an earth connection to the loop to energize a differential relay DF. The keys, as shown, correspond to (1) start/stop (KSZ), (2) rewind for playback (KRW), (3) letter index for marking a desired part of the record (KLI), and (4) call supervisor (KCS). In each case relays DF, CS pull up in turn and then fall back, and resistance R1 and rectifiers MR2, MR3 associated with the keys ensure the operation of (1) neither of two relays X, Y, (2) relay X, (3) relay Y, or (4) both relays X, Y.

Inventors

• 👤 Geoffrey Charles Curson

Bibliographic Details