Show audio p pp p OR I o c I Ir c o oc Oom r c A 6 V The Wiring Diagram of the Amplifier Herein Described Gy Dy SIDNEY E FINKELSTEIN In New York Tribune Herald The honors In frequency audio am- am amplIfication am amplification seem to be divided more or orless orless less Jess evenly evenly between the transformer and the resl resistance tance coupling methods tell Fitch system has Its stanch adherents who are ever ready re to fling masses of facts figures and anel fancies Into each others faces whenever a discussion of relative merits arises The trans trans- transformer transformer former supporters are just as firm In their belief of the superiority of their Instruments as the res resistance hench hench- henchmen henchmen men are In their views on the adan advantages advantages ta es of their devices The writer has s used both transformers transform transform- ers eta and In the construction construction construction tion of a n lar large e number of ot sets and after studying the tIle general Jeneral results ob- ob obtained obtained ob obtained from them has hag come to the neutral conclusion that both systems are good but that they aro even bet bet- better better ter If It they are combined in the jour jour- journalistic journalistic fashion to the ot of the best features of each The TIle advantage of the greater am am- amplification amplification per stage stas-e afforded by the transformer combined with the flawless flaw flaw- flawless less reproduction hut but lower amplIfication amplification tion of the makes the Ideal combination in the majority of sets A complete amplifier of this ad- ad advantageous ad advantageous type can cnn be made at home at surprisingly little trouble and ex- ex expense expense ex expense pense and once on hand It finds ap- ap application ap application to receiving circuits of ot all kinds It may be built permanently Into a set ret or It can be left available as a separate sep unit for connection to experimental tuners For the last purpose It Is especially convenient ns as It sa saves es the constructor of or a n new set the worry of providing suitable amplification to follow the detector tube Parts Required An amplifier such as the one shown In the Illustration will require the followIng parts which can be pur pur- purchased chased ha ed at any radio store lIar Hard Haril rub rub- rubber rubber ber her or composition baseboard 12 Inches long 47 4 4 Inches wide and 1 j i Inch thick one heavy audio transformer not above e 3 31 to 1 ratio three stand stand- standard standard standard ard tube sockets two resistance cou cote coupling coupling pling units with two one BOO and one ohm resistors one fired flied condenser eight bind bind- bindIng binding binding ing posts and the usual bu bar and mounting screws A definite assembly procedure should be followed First the general location of ot the Instruments should be determined and all the necessary screw holes made In the panel before any anything Is fastened down permanently perma perma- permanently permanently The devices should be pushed closely together there Is no danger from h howling ng as ns there Is la only one transformer so as to allow r room om on the right and left hand hantI short edges edges for Input and output bIndIng posts The wiring will give gle no trouble As a start the P I and n B posts ot of the amplifying transformer should be connected directly to the two bind bInd- bIndIng binding binding ing posts on the extreme left whIch are designated as the Input ter ter- terminals ter- ter terminals terminals The fixed con con- condenser condenser condenser denser Is also placed across the wires and can cnn be hidden en comfortably out ot of way beneath the bottom of ot the baseboard Of Ot course small holes have have to be drilled In the com com- composition composition composition position to pass the wires wherever necessary The Filament Pott Poste Posts Next the filament posts of the three sockets which are all marked F ere are wired as shown shonn In n the diagram and It lead finally to the A battery binding posts posts These should be the left hand two 1 of ot the row of ot tour four along the long edge of ot the baseboard With this much done the secondary ot of the transformer can cnn now be he wired to the grid and filament posts of the first tube socket Progressing across the con condenser and resistor terminals ore are wired In the manner Indicated d In Inthe inthe Inthe the accompanying hook up With the resistor units that were employed In Inthis Inthis Inthis this particular amplifier the protruding protruding ing soldered tabs of at the spring mount mount- mountings mountings ings make the placement of at the wIres a short and simple task The two posts on the extreme rl right ht are the time output To one 1 Li 3 run a wire tram from the P I terminal of ot the socket and to the other a wire from the C n plus post which Is Immediately adjacent The he A plus and B n minus po posts ports t It will be noted are joined to- to together to together eth gether r All the wiring should be lie done with standard round or square tinned bus hus- bar Mr The wire need ell be he Insulated with cambric tubing only In places where two wires unavoidably pass each other very closel closely very ery little cover cover- coverIng covering ing log will be found necessary Tile The connections to the transformer the tube tub sockets the tho tb binding po poets ts I which are all nil equipped with strong I screw binding posts need not be soldered but those to the fixed fired con con- condensers condensers con condensers and the resistor mountings must be The B battery should be of volts which Is the standard require require- requirement requirement ment for resistance amplifiers With this voltage the ohm resistors should be he employed In the plate cir cir- circuits cir circuits cults of the first Olst two tubes while the ohm leak goes boes between the first and second bulbs and the ohm resistance between the second and nd third In the grid leak positions This Is clearly shown in the wirIng diagram |