TALKING CLOCK
New Telephone Service At the Post Office Research Station recently a demonstration was given of the “talking clock” system, by which telephone subscribers will soon be able, on dialling TIM, to hear the time announced from the Tandem Exchange building in Holborn. The service will be made available to the public on July 1, and will, in the first place, be confined to London, says “The Times.” On dialling TIM the subscriber will be connected with tho clock in the same way as with the switches at any other exchange, and will be allowed to listen to the time announcement for a period of from 90 to 180 seconds, when the call will automatically end. The time is announced by-the’ clock at intervals of ten seconds, and, assuming that the call is made at 3.10, the announcement will be in the following terms:—“At thb third stroke it will bo 3.10 precisely.” There follow tho three strokes, technically known as pipe, and the clock goes on to announce: * ‘At the third stroke it will be 3.10 and 10 seconds.” The next announcement is for 3.10 and 20 seconds” —and so on.
The clock consists of four glass discs rotating on two shafts. On the discs are a number of concentric circular sound tracks which constitute records of the numbers from 1 to 59, words such as “o’clock” which are required in building up the time announcement, and tho initial and final parts of the sentence. The words aro recorded in much the same way as speech and music are recorded on the track placed along the edge of a talking cinematograph film. Speech is reproduced from the discs by focusing a beam of light on to one of the tracks and allowing the light which passes through to fall on to a photo-electric cell, thus producing an electric current which may be amplified by means such as are employed in talking pictures. As the clock can be checked by comparison with a signal from Greenwich Observatory only once an hour the speed of rotation of the discs, must not vary by more than one part in 36,000. In order to meet this requirement a novel type of drive has been devised. A pendulum, beating seconds accurately, has fixed to its end a shutter swinging in front of a photo-electric cell. A light is focused on to this shutter, and is so arranged that as the pendulum swings the light on the photo-electric cell varies in a regular manner four times a second. The current produced by light shining on this cell is amplified, and finally drives to rotate the clock by means of a synchronous motor.
Miss Ethel Cain whose voice was recorded for the purpose of the clock, was present at the demonstration.
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Bibliographic details
Hawke's Bay Tribune, Volume XXVI, Issue 110, 22 April 1936, Page 7
Word Count
465TALKING CLOCK Hawke's Bay Tribune, Volume XXVI, Issue 110, 22 April 1936, Page 7
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