LATEST IN RADIO.

Auckland Star, Volume LX, Issue 257, 30 October 1929, Page 17

LATEST IN RADIO.

MARCH OF PROGRESS.

ITS WONDERFUL RAPIDITY.

DEVELOPMENT IN DOMINION,

EVOLUTION OF THE RECEIVER

Auckland is having its first big radio show. To the uninitiated this implies just a collection of different types of receiving sets, displayed on various stands. In reality, Auckland's exhibition will be far in advance of this, for the public who visit it in their thousands will have opportunity of seeing very much that scientific research has contributed in making the enjoyment of the broadcast listener true, efficient and simple. In addition, they will be able to appreciate both ends of radio service, for they will see the actual presentation of programmes undertaken in one part of the hall, and will hear the result, transmitted through IYA and picked up on receivers in various parts of the building. Only the transmitting apparatus itself will be missing, for it would not be economically possible to remove the plant temporarily from the station in Karangaliape Road to the Town' Hall. Still there will be on demonstration smaller transmitting plants that show "just how the trick is performed."

World's Big Display. I The great scope of a big radio exhibition may be gleaned from some particulars of novelties shown at the annual New York Radio Fair, the biggest of its kind in the world. Though not all of these have yet reached New Zealand, visitors to the Town Hall will probably be astounded to note how much of what is latest in radio development has already been introduced to the Dominion. In its short yet hectic period of evolution the receiving set has changed from a weird contraption to an artistic piece of furniture. The modern set must be one which first of all pleajes the eye, and the attention given to cabinet work is one of the first impressions gathered when one views an assembly of all types of receivcds In this respect they have followed the evolution of the gramophone cabinet. The console model has raptured public taste to a proportionately greater extent than the cabinet gramophone has in comparison with the portable for there is far less necessity for the radio set to be carried from room to room than there is for the gramophone to be thus summarily treated. The handsome console model devoid of any external accessories except the necessary power antennae and ground wires leading to and from it makes a fine piece of furniture, anc< this, in the modern home, is an essential in any radio apparatus. Novel Developments. But developments have gone far beyond [ this point. The costly, cumbrous and unsightly batteries are things of the past for those who desire the latest, and the receiver of to-day in its highest form is a complete unit, with loud-speaker embodied in it. Construction has gone further. Attachments are provided whereby the gramophone can be played through the radio set. with all the refinements of tone and volume obtainable through electrical reproduction. This step has been followed by the combined radio-gramophone, which either receives music from the air or plays a series of records, the change o T -er being secured instantaneously merely by the snapping of a small switch. Thus, at will, the owner can have the voices from the air or the voices from the discs. One of the most recent appliances for the convenience of the broadcast listener was displayed last month in New York. There was once a time- when one of the principal delights in possessing a radio set was that of twirling three or more knobs and playing the wizard, with a "There! That's Sydney!" to a marvelling audience. Now the listener may sit comfortably in his armchair, having beside him a small ' distant tuning" device, connected with the set by a length of flex. With this device, which may be taken to any part of the house, according to the length of flex, he may control both tuning and volume of his receiver. Radio developments are surely catering for the inherent, laziness of humanity in the mass. , Modern Construction. A peep at the "internals" of the modern radio receiver is a disappointment to those who love the sight of coils, connections and glowing tubes. The set of to-day resembles nothing much more than a collection of carefully-finished metal cans. "Shielding" has become a generally accepted practice, and its results are instantly noticeable by comparison of reception with unshielded models. The resultant neatness and compactness have made possible the artistic form in which the set is housed. Whether it be incorporated in the cabinet or displayed as a separate unit, the loud-speak.r (an unsuitable term, which cannot survive much longer) shows an evolution as remarkable as that of the set itself. Every effort of the technical man has been strained to produce complete fidelity in all ranges of tone, with the result that the speaker of to-day is to its earlier prototype what the grand

organ is to the wheezy harmonium. Whether cone, horn, flat "washingboard," or '"'Jack Horner" in type, the up-to-date speaker is a faithful servant in its reproduction, and the radio engineer has rendered service not only to his own branch, but to the talking film, in his evolution of the electrical reproducer of sound.

Another development that eliminates the personal element and helps to get good reception without attendance, reducing xading and blasting in radio reception, is the year's contribution of the automatic volume control that increases the strength of weak or distant signals and reduces the volume on strong signals. It may be set so that no signal will come in over a predetermined volume, and ends to keep all other signals easily audible without manual attention. This is just another item in improvement that awaits new Eet owners who did not like the bother and fuss necessary in tuning-in on earlier receivers. Accommodating the "Pick-up." ; One of the leading features, in coming radio receivers is the arrangement for accommodation of the phonograph pickup that enables the owner of a radio receiver of the future to play his own phonograph records electrically through the radio amplifier and reproducer incorporated in the set. This feature is an interesting one and quite convenient when the listener wants to hear some particular piece of music that is not appearing 011 any radio programme, or for producing a complete dance programme from one's own record album. This is the same system used for giving the motion picture screen its voice, and the talking picture is one of the commercial outgrowths of this original radio development.

How to do it in one's own home is) a. simple job now that the set designers have placed jacks and switches on the new receivers so that the pick-up may be easily attached.

The magnetic type of pick-up is generally t regarded as the best and most convenient form for home use, as it may be placed in circuit with the proper amplifier in the set with almost no other circuit additions. The magnetic type of pick-up consists of a strong permanent magnet, with a movable magnetic vane placed close to the pole pieces. This vane carries the phonograph needle. ' The vane is also placed in the field of a coil adjacent to the magnet, so that when the needle, which follows the mechanical vibrations of the phonograph record track, moves or vibrates back and forth, a corresponding voltage is generated at the terminal's of the coil. This voltage is then applied to the amplifier in the set by suitable connection, and the currents are amplified and finally reproduced by the set's loud speaker. In this way the phonograph music is "played" by the radio set and the reproduction is as perfect as in the best type of electrical phonographs; in fact, it. is exactly the same, because the same electrical method is utilised. Metamorphosis of Broadcasting. "Less than eight years ago radio was a toy. To-day, it is not even a luxury; it is a necessity in every home." This is an old-world opinion that may not yet be applicable here, but New Zealand, like other countries away from the great centres of art, literature, music and history, is progressing towards the stage indicated as existing in the densely populated areas of the civilised world. "Increased demand, increased production, lower costs, lower selling prices and greater values." These are given as the chief factors contributing to the growth of listening-in during the past year, and they apply directly to New Zealand, as those who have followed broadcasting from its inception here are quick to recognise. "The public is appreciative of the opportunities afforded it in buying a radio set whose qualities of reception and tone are far better than those ever dreamed of "a few years ago, yet at a price less than the cost to manufacture at that time." Television Progress. Though the system of transmitting through the air both voice and moving picture is still in the experimental stage 5 , remarkable progress has been made during the past year, as was evidenced at the Radio lair in New York in September. There a television apparatus, the invention of Dr. E. P. Alexanderson, was publicly demonstrated, and on glass screens a foot square visitors were able to observe the actions of singers and speakers who were located in a special television studio some distance away. The increase in size of the visual images, and the distinctness of the reproduction, were the chief features of scientific advance noted.

Dr. Alexanderson's television transmitter essentially consists of a powerful source of light which flashes on the image being transmitted. A huge disc containing 48 holes arranged concentriis attached to a motor revolving at 1700 revolutions a minute. As the holes in the disc sweep across.the image, light passes through and acts on the sensitive element of a photo-electric cell. This cell converts the light impulses into electrical energy, which is transmitted by radio to the receiving apparatus.

At tiie receiving set an identical disc, revolving in absolute synchronism, repaints the picture of tiie televised image on the screen. The receiving disc revolves in front of a glow tube, which varies in light intensity proportionately to the frequency and strength of the impulse recorded by the photoelectric cell at the transmitter.