RADIO-OPERATED MACHINES

Press, Volume LXXV, Issue 22877, 25 November 1939, Page 20

RADIO-OPERATED MACHINES

POST AND TELEGRAPH DISPLAYS MANY INGENIOUS DEVICES j AT EXHIBITION One of ‘.the interesting exhibits in the Government Court. at' the Centennial Exhibition is the radio section of the Post and Telegraph : Department’s display, which includes several modern “wonders” of science - adaptable for domestic use. This section includes devices by which a bell may be rung merely by waving the hand: a telephone dial, which will set' all sorts of domestic electrical appliances. in operation bythe twirl of a finger; and a - machine which enables visitors to see the sound of Jtheir” own voices translated on a screen. The magic dial, as it is called, demonstrates the use of ultrashort radio waves in,-.communication. A radio set, electric lights, and other apparatus may be set in operation by the dialling of particular numbers. The telephone dial',; which -is ~ mounted oh a small box, may be carried around

within the borders of the stand, and in the home it could be. used in any part of the house for turning on an electric stove, water jug, radio, or toaster.

The box. with its “magic” dial, js an, ultra-short wave radio transmitter, which transmits signals in accordance with the number indicated by the dial. These signals are picked up .by receiving sets. which, in turn, switch on the particular device.

Looking at Sound A device, which is revealing new possibilities, is the machine which demonstrates how the counterpart ot sound waves in air may be dealt with for radio transmission and telephony. This exhibit gives a visual demonstration of the nature of electric currents corresponding to sounds of different kinds. A number of buttons producing different pitches of pure musical sound are arranged so that, as any of' the buttons is pressed, its sound is recorded on the screen. Sounds of different pitch produce different patterns On the screen of the oscillograph, illustrating the high and low electrical frequencies of the varying notes of the musical scale

Normal speaking tones may also be shown* on the screen, and it has been found that the sounding of pure vowels-'in speaking produces more distinct patterns than those produced by slovenly speech. For singing, too, valuable visible proof ' of the purity of notes and enunciation is given.

A tall chromiumrplated standard is the form taken by the invisible bell push. By waving a few inches in'front of it, it’-is possible to ring a bell in a distant part of the exhibit.