GB1097946A - Improvements in or relating to electrical impulse transmitters - Google Patents

Abstract

1,097,946. Impulse transmitters. TELEPHONE MANUFACTURING CO. Ltd. Feb. 11, 1966 [Feb. 24, 1965], No. 7909/65. Heading H4K. A straight pull impulse transmitter has a plastics belt, preferably polypropylene, with sections of reduced thickness for flexibility, and which is movable manually to a number of alternative setting positions by means of numbered finger stops carried on the upper exposed side of the belt, projections carried on its underside and positioned in correspondence with the finger stops operate, during the automatic restoring motion, an impulse mechanism a number of times dependent upon the setting position. The belt 11 meshes with a gear-wheel 18 and during the setting motion, as it is pulled from right to left, winds up a restoring spring 20, the nylon trigger 57 being rotated into a vertical position by the first projection a where it remains and is repeatedly depressed, as all projections pass over it, to cause the stud 50 on its supporting lever 47 to press the contact springs 44, 45 together and so self-wipe their contact points. The selected finger stop travels as far as X-X and upon the release and the return of the belt the trigger is rotated back, providing a lost motion period, and is successively depressed by the projections to open the impulse springs by lugs 57 as shown. In the home position-of the belt a stud 39 as on the gear-wheel 18 opens successively two contact pairs (33-34, 35-36, Fig. 1, not shown), one of which had been short-circuiting the receiver and the other of which is in series with the impulse contacts. The mark-space ratio is adjusted by means of an eccentrically mounted screw 56. The mechanism is enclosed within two casing-halves each having a groove in which an edge of the belt runs.