AN T LEVI S N Tt ME5 M. E I EDITOR F.J.
MAKING A KILO -VOLTMETERjune: 1957ANM.T E LEVI S ION/ « «4)/TtM E5EDITORF.J.
PRACTICAL TELEVISIONTELEVISION TUBESMULLARDCOSSOREMITRONI2in.VI4in. 7.0.0I7in. 8.10.0I2in. 6.10.0I4in. 6.10.0!7in. 8.10.0I2in. 6.10.0Kin. 7.0.017in. 8,10.0I2in.MULLARD. 6.10.0now6weeksAll other types ex -stock.delivery.MONTHLY CLEARANCE REDUCTIONSSin. 6.10.0MAZDAKin. 5.10.0I7in.MULLARDI6in. Metal Cone 5.10.0Kin. 6.0.0CATHODEON.I7if i.1.MetalConeI7ir.All1957June,Tubes plus 7.0.0 6.10.0. 7.0.012/6 carriage ar d insurance.MONTHS' GUARANTEESIXTerms to the TradeRE-VIEW (LONDON) LTD.81,HIGHMERTONSTREETTelephone:CHERRYWOODS.W.I 93255PREMIER RADIO COMPANY6OPEN TILLP.M. SATURDAYS(Regd.) B. H.(Dep.P.T.}207,TelephoneMORRIS & CO. (RADIO) LTD.:AMBASSADOR 4033PADDINGTON 3271EDGWARE ROAD, LONDON, W.2SAFETY FIRST!Build thesePREMIER TELEVISORSwhich give complete safetyto the constructorIThese Televisors use a double wound mainstransformer which gives you complete safetyfrom contact with che mains supply whenhandling the chassis or controls.BBC & ITA(WITH NEW TURRETTUNER)DESIGN No.PLUS COSTMAY BE BUILT FOR 33.7.11 OF C.R.T."jSrIWHY ii IanteedBBCDESIGN No.MAY BE BUILT FOR 27.9.47.ON SOLECABINETSlength doors for 14m-.n, and i7in. tubes.PRICE 14,14.0, H.P, TermsDeposit'.6and 9 monthly payments of 18 6.M NETS, half door, still available at 12.12.0. H.P. Terms"it 6.6.0 and 8 monthly payments of Id '3,withableCHANNELS!(ALLPLUS COSTOF C.R.T.TheTubeline,21'- extra.5ur P' us or reconditionedlatesttype 17m. Rect64 by Telefunkenpost and packingMW43tax)Also Min. RectangularTube TypePkg,full!angularat 17'"J 'rtubes when these Fully Guar.Wide Angle Tubes are avail-&14 LP4, 13.17.6 (inc. tax).carr. 15/- extra.:CONSOLE MAY:Onabove cabinets add21-for pkg. and carr.BE EASILY BUILT IN S SEPARATE UNITSFULL CONSTRUCTION DETAILS AVAILABLE. INSTRUCTIONBOOK 3 6 POST FREE INCLUDES BOTH DESIGNS.SENDI'd.STAMP FOR OUR1957CATALOGUE
Ja@ !Q0: Oi.fl1& TELEVISION TIMESEditorF. J.CAMMEVERY MONTHNo. 83Vol. 7:TELEVIEWSiAd erli.4ememan ttKditori;i!1Offices:PRACTICAL TELEVISIONGeorge Newnes. Ltd. Tower House.So»l h llll f im Street, strand. W.C.2.PhoneTextile Bar 43*3.Telegram*NciwMS. K.iud. London.\T Registered at tfre G.P.O. for transV misiio-! by CsmkfKiM Mstej»*ine Post.JJl::SUBSCRIPTION RATESincluding postage lor one yeariJ Inland------17s.annumannumannum66. perIAbroadCanada3Editorial*Beginner's Guide to116*. 6d. per16s. perCONTENTSTV.An Automatic TV Clock .fServiciiig the tironictEO 1523 and FCV1527.TIABand MlLoft.Starting a Service Dept, .A Projection TV" Improve-menr.Making; a kilo- voltmeterOsci!I?„it.r RadiationFdenewsPaue503504507509Aerial for theK C.R.T. Qualin fester\.Underneath Hie Dlpole.X Correspondence% Your Problems Solved)512515517.521.524.526.531.535539543The EUter will be pleased to consider4 articles ot a practical nature suitable 1 for nub'icution in ''Practical Television"f Such articles should be written on one side of the paper only, and should coni tain the name and address of the sender.Whilst the Editor does not hold him setfi responsible lor manuscripts, every effortwill lie made to return them if a stampedentiou-it. Alland addressed envelope'; correspondence intended for the Editorthmdd bp addressed to : The Editor,4- " Practical Television," George Newttex,'-h'-* Ltd., Tower Home, SouthamptonI' -,:-i j-iJi-4:-PJUNE. 1957Strand.Owing.Stive'.W.C.2.to the rapid progressin thedesign of radio apparatus and to ourefforts to keep our readers in touwe give nolatest developments,tin'warranty that apparatus described in.rfair columns Is nor the subject i'J tellersputenr.Copyright in all draxinzs. photoand article* published ingraphs" Practical Television ''throughoutreservedthscouniricAgnamry to the Berne Convention andthe C.S.A. Reproductions or imitationsof any of these arc therefore txtI 'Hdden.'--HQCOLOUR TVANINAMERICAextraordinary situation has developed in America as aof the too-early publicity relating to colour television. The American public was led to believe that itwas just round the corner. As a result, the sales of black andwhite receivers dropped considerably and several of the largecompanies were therefore forced to cut their prices below costSome of the large firms, suchin order to clear their stocks.as Columbia and Raytheon, decided to cease manufacture oftelevision receivers, and they disposed of their stocks at lowOther manufacturers were forced to follow suit. Atprices.the same time, R.C.A. was indulging in an intensive campaignof propaganda on colour television, and its associated network,N.B.C, was putting out three hours of colour programmes aday. As a result, the American public presumed that colour television was near and they declined to buy black and white receivers.As all manufacturers had cut the prices of black and whitereceivers, a price level was established for that type which wasnot really representative of the true value, and so there is agreat disparity between the market price of a black and whitereceiver and a colour receiver, the former costing about 160The American public isdollars and the latter 500 dollars.therefore not prepared to pay what it wrongly considers to betoo high a price for colour TV.The inevitable result is that there is now only one manufacturerin the market, R.C.A. , which manufactured only 102.000 coloursets last yearyet three years ago, SarnolT publicly stated thathe had budgeted for an annua! production during last year of overIt is not surprising, therefore,6 million colour TV receiversthat the American television industry is in a very bad way.Those who have tried to receive the colour television programmeson black and white receivers, especially those a long way fromthe transmitter, complain of the poor quality and that theEquafly, reception ofpictures are full of dots and distortion.black and white transmissions on a colour set is inferior. It iswell-known that colour television receivers arc troublesome andrequire a great deal of servicing, and the service engineers donot exist in sufficient numbers. This country can take a lessonfrom America in this respect and manufacturers should ceaseto talk airily about colour television being round the corner, ifthey do not wish to duplicate the American experience.Although colour television is inevitable it will be some yearsbefore it has been brought to the stage where it possessesentertainment value, and the technique at present will needconsiderable improvement possibly an entirelv new systemresult;!—'F. J.Ournext ixauo, dated.fitly, trillbe published on June fist.C
504PRACTICAL TELEVISIONAfleginmeri RuideJune,1957toTMiswMmTECHNICAL TERMSByF.ImageDriftATERMJ.[confd.Cammthewhich sometimes occursinconsequence ofslight hick of synchronisation.IncidentHayName applied to any ray oflight whichobject ornot straight in this t\pe of tube but is offset sothat the beam would normally fall outside the faceof the tube The magnet deflects only the tighierpart of the beam and brings it, when properlyadjusted, on the face in the normal manner, but theheavier ions carry on the original path and thus donot strike the screen.isreferring lo the drifting movement ofreceived image on a television screenfallsupon anmedium.lonisationtelevision terminology this expression refersthe production of '"ions"' within an electricdischarge tube such as. for instance, a neon tube.InHeated Cathodecathode heated by an electrically separate elementIndirectlyAknownas the heater.Intensity ModulationThe usual method of modulating the outputcurrent of a television transmitter by means ofvariations in the intensity of the light reaching thephoto-electric cell of the transmitter.IntercalationSynonymous nterlaced ScanningtoThe neon tube contains a small proportion ofneon gas. An electrical discharge passed throughthe tube strips away some of the outer electronsfrom each atom of neon gas. Owing to the loss ofnegatively charged electrons, each atom of neon gasshows a positive charge and it is called an *' ion,"the electron-stripping process 10 which it has beensubjected being termed " lonisation."Ions are electrically conductive. Hence, when theyare present in comparatively small numbers within agas discharge tube, they allow the current to passand they give off a charact eristic glow. The glow ofelectrically excited neon ions is, as is well known,a pinkish-orange shade.Asystem of exploration of the scene or imagewhich complete scanning is accomplished in twoor more operations, the strips of scanning lieldsuccessively traversed in the course of one operationnot being contiguous. During subsequent operationsThe operating condition which obtains when theicconst ruction of the image and the scanning of theobject occur at the same time.the lines previously omitted are scanned accordinglo some set rule or order.Light-sensitive CellinIsochronismAIonAn atomofitswhich has been stripped of one or moreSee lonisation.electrons.general term applying to any electrical devicewhich, on illumination, undergoes a modificationin its electrical properties. All photocells are includedunder this general definition.Ion BurnMagnetic FocusingThe dark patch which forms on the face of a tubedue to its bombardment with the heavy ions of theAvoided by using an aluminisedelectron beam.Term referring to a method of focusing the beamof rays in a cathode-ray tube by placing an electromagnetic coil in their path.screen or an ion nap.IIon Trap(Beam Bender)A small magnetspeciallymadeplaced at the rear of the neck of atube to prevent ion burn. The gunisxajou's FiguresAny closed figures traversed by a point movingwith the resultant of two periodic oscillatory motionsat right-angles. Originally applied to certain experi-
June,in connection with pendulums and sound, butused for u class of records of this nature by suchinstruments as the catlwde-raj oscillograph.mentsnowfjnmDefinitionsystem of television in which the number ol"scanning lines into which the complete picture isdivided is less than 100. Low definition systems arefKJW obsolete.Anearlyreflect the televised picture on to a screen.the object of these methods being to increase theintensity of the illumination on the screen.drums,Negative ImageAMirror505PRACTICAL TELEVISION1957An image resembling that shown by a photographicnegative, i.e. one in which the light parts of theoriginal picture are dark and the dark portions ofthe" original are light. It is the opposite of a positiveimage.Drumobsolete scanning device lly, ithaving fixedinsomeconsisteduponOf aperiphery or outer eds»e a number of minors, eachSometelevision receivers will give rise to negativetheir screens when a fault oi* maladjustpresent in the electrical circuit of the receiver.images onmentisitsXLNeon TimebaseName given to a limebase circuit in which a neonlamp provides the means of providing a periodicvoltage across one pair of deflector plates in acathode-ray tube.Nipltow DiscNamesometimesemployedinmanygiven to thetelevision systems.scanningItwasdiscorigin-Paul Nipkovv.crude shadowgraph transmitters with which he experimented atthe end of the last century.ally the inventionin 1884.of the PolishNipkow employedscientist.itin theObjectiveA frequently used term which denote* the imageforming or projecting lens of an optical instrument,as, for instance, the projection lens of a television orfilm/television apparatus.OrthiconThe special camera used for television.American name for the Emitron camera.TheOscillatory ScanningDiagram of a mirror screw.mirror being tilted at a slightly different angle frombeam of light isthat of the preceding mirror.suitably focused upon the edge of the mirror drum.which is rapidly rotated, thus causing a light spotto be Sashed in successive lines over the image orobject to be televised.In a simitar way, also, the mirror drum is made toassemble the televised picture at the receiving end.The main advantage of the mirror drum is that itallows a more intense spot of light to be focusedupon the object.AMirror ScrewAnother obsolete scanning device comprising anumber of" mirrors arranged on a frame in the formof a screw spiral. Unlike the mirror drum (whichsee) the mirrors are not separately tilted in relationto one another, the directing of the light spot on thescreen or on the object to be televised being effectedby the suitable and esuict positioning of the mirrorson the spiral.The mirror screw does not reflect the light as doesthe mirror drum. It has. however, the advantage ofgreater compactness.Name given to scanning methods b means ofwhich the light spot oscillates or navels forwardsand backwards over the image to be televised. Aftereach complete oscillation theMaskLensDetails of the mirrorExpression referring to television systems in whichdevices, as, for example, two mirrordrumprojector.thus enabling the new area of the picture to beOscillatory scanning possesses manyscanned.practical disadvantages.OscillogramName given to the wave-like pattern, representingthe graphical form of an alternating current, whichby the light spot on the fluorescentis traced outscreen of a cathode-ray oscillograph tube.Multiple Scanningtwo scanninglight spot shifts laterally.OscillographSee cathode-raj tube.
506PRACTICAL TELEVISIONOut of FrameThe state of aJune,1957Picture Elementstelevised image when, as seen on thescreen of the receiver, it is divided horizontally orvertically, the two portions of the image appearingin opposite positions. The image is correctly "framed"by the manipulation of a small control which influencesthe synchronising gear of the receiver.Name given to the minute areas into whi:hpicture, portrait, or scene which is to be televisedParabolic Reflectorsignal current.Name given to a light reflector, usually of highlypolished metal, which, being shaped to a paraboliccurve (a parabola is the section of a cone cut parallelto one of its sloping sides) causes a beam of parallelrays to be reflected from an illuminating sourceplaced in the focus of the reflector.Parabolic reflectors are frequently meiforobtaining strong beams of parallel, light rays inoptica! experiments connectedwith illuminatingandlight-projecting matters.Parallel 'RaysLight rays which travel parallel to one another, as,for instance, the light rays reflected from a parabolicreflector.Light rays coming from a very distantobject, such as the sun, are always parallel from apractical standpoint, although, in strictest truth, iheyare very slightly divergent.Persistence of VisionWhenlight rays impinge upon the retina of the eyeimpression which they make does not ceaseimmediately the light rays stop. On the contrary,it persists for an appreciable time afterwards,thisMeffect being known aspersistence of vision," or" visual persistence."It is upon this " lag of the retina," as persistenceof vision is sometimes called, that we are able to buildup a reproduction of motion on the television orcinema screen, in both instances a series of successivepictures (each differing slightly from the precedingone) being formed or thrown on a screen so rapidlythat the eye is not able to get rid of the impressionmade by the one picture or image before the next onethearrives.orPicture FrequencyThe number of complete images transmitted persecond.PolarisationApplied to light rays the term denotes the cullingoff of all the rays in a beam of light except thosewhich vibrate in one plane. Light consisting of theseone-plane vibrations is said to be '* polarised " and,in such a condition, it possesses peculiar propertiesof its own. Light rays are usually polarised bypassing them through certain crystals, such as IcelandSpar, which effect the process automatically.Positiveimage.Plioto-electric CellA light-sensitive device which,by emitting a streamof electrons under the influence of light rays and inproportion to the amount of light falling upon it,enables light to be turned into electricity.Photo-electric cells are of two kinds, viz., theEmission type and the Photronic or self-generatingtype.Photo-electronsName sometimes applied *o the stream of electronswhich are liberated from certain bodies under theinfluence of light.Photo-electric cells operate in virtue of the presencewithin them of a stream of photo-electrons wheneverthey are illuminated by light rays.ImageThe imageas it is normally seen on a televisionscreen.photograph or any other type of illusltion is a positive image, the lights and shades of iibeing a true or approximate reproduction of (hoseof the original.positive image is, as its naq&eimplies, the opposite to a negative image.AIAPrimary CurrentA term used in connection with gas-filled pho soelectric cells to signify the actual minute current setup by the impact of light upon the sensitive cathodeof the gas-filledcell.PrismA triangular-shaped piece of glass or other transparent material used in practical optical work forbending rays of light through a right-angle, and alsoin the spectroscope, for spl tiling up rays of tight intotheirAdetermined by the instantaneous value of iheisPtiasc Shiftcondition in television reception in which, owingto stray circuit capacities in the receiver, the fluctuations in voltage do not keep in step with thoseoriginally transmitted, particularly at high and at lowfrequencies. This results in some of the details of thetelevised picture being received at a later instantof time than the remainder of the picture, therebysetting up a displacement or distortion of the televisedaisup by one means or another. The pictureelements are all of the same size, but they differ inbrightness. The portion of the scene which determinessplitcomponentcolours.Progressive ScanningA system of exploration of the scene or image inwhich continuous strips of the scanning field aretraversed in order.RasterThe rectangular picture area built up by thescanning spot on the end of the cathode-ray tube.Recurrent VisionName given to the phenomenon of an image recurring one or more times to the eye after the actuallight rays from the object have been cut off.Recurrent vision was first noted by Young in1801, who observed that after an object had beenintensely illuminated by an electric spark, the imagerecurred to the eye several times after the spark hadpassed, the image becoming fainter with each successive recurrence.ReflectionTherecoiloflight raysfrom the surface on whichthey impinge,(7V be comintted)
—507PRACTICAL TELEVISION1957June,[L C MECHANICAL DEVICEFOR SWITCHINGON OROFFA TV OR RADIOSETBy Michael Dunnhappena large and busy familyIT can sotheeasilybeginning of a much-desired televisioninthat-for radio) programme is missed, simply becausenobody remembers to switch on at the right timein fact, ii is sometimes remembered only after theentire programme has ended. With the device to be;describeditisbell was retained hi .situ and switched in parallelwith the output. The hell can, therefore, serve thevery useful purpose of calling the family from remoteparts of the house or garden, at the same time asthe set is switched on.possible to set the timer at leisure,any convenient time prior to the programme, sothat it will switch the set on automatically at theIt has proved its value over anddesired moment.Thewas simply to use the clock toit was soon realised thatimprovement would be effected if the setcould be kept on indefinitely and this is done byutilising the current drawn from the mains by theset itself to drop a few volts which will operate aoriginal ideaswitch on the television, butover again."La"'alarmEssentially the unit consists of anclockwhich will switch on the set and an auxiliary circuitwhich will maintain it switched on indefinitely.Although the following details refer to the writer'sown model, the principles involved can be subjectto personal variation and improvement, both asregards the choice of components and the generalThe entire unit was made from od
June,1957 PRACTICALTELEVISION 505 flectthetelevisedpictureontoascreen .
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CLAUDE LÉVI-STRAUSS. Claude Lévi-Strauss 28 November 1908 - 30 October 2009. Elected Corresponding Fellow of the British Academy 1966* by. JAMES J. FOX. Claude Lévi-Strauss was a major figure in anthropology. In 1959 he was appointed to . the Chair of Social Anthropology at the Collège de France, a position he held, with
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the birth of Levi's son Merari, while the Aramaic continues. Here the one responsible for the insertion very probably had a fragmentary text before him; he inserted it in an awkward place. (13) See again H. W. HOLLANDER-M. DE JoNGE, Commentary, pp. 19-20 with a reserved reaction on further suppositions about the contents of the Levi-document by .
“Rita Levi Montalcini” di San Giorgio del Sannio, è elaborato ai sensi di quanto previsto dalla legge 13 luglio 2015, n. 107, recante la “ Riforma del sistema nazionale di istruzione e formazione e delega per il riordino delle disposizioni legislative
Il curatore e manager dell'opera ne ha dato la disponibilità. VENERDI’ Ore 17.00 Apertura OMAGGIO A RITA LEVI MONTALCINI . Hypatia Festival 2017, dedicato al cervello in omaggio al premio Nobel Rita Levi Montalcini, si apre a Palazzo Salerno che affaccia su Piazza del Plebiscito.
Ricerca, nuovi laboratori per tecnopolo Rita Levi-Montalcini 35 14/01/2020 imalatiinvisibili Malattie neurodegenerative, Bologna - Cresce il Tecnopolo "Rita Levi-Montalcini" 36 14/01/2020 magazine.unibo.it Tecnopolo di Bologna: cresce la sede di Ozzano "Rita Levi Montalcini" 38 14/01/2020 altoadige.it
5. LO STRUTTURALISMO DI LÉVI-STRAUSS «L’antropologo Claude Lévi-Strauss è stato colui che, con la utilizzazione del modello della linguistica strutturale nelle indagini sulle strutture di parentela e sui miti, e con le sue teorie generali sul concetto di struttura, ha più contribuito alla formulazione e alla diffusione di quello .
