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NATIONAL
1SCHOOl.S‘* l.OS ANGELES 37, CALIF.
PRINTED IN
U.S-A.
souun P|c1'um:é mm“-
L E S S O N
N O. SP - 2
SOUND
RECORDING ON FILM
- IN THIS
LESSON HE ARE GOING TD DISCUSS A TYPE OF SOUND RECORDING,
WHICH IS
ENTIRELY DIFFERENT FROM THE DISC METHOD ABOUT WHICH YOU LEARNED
IN THE
PRECEDING LESSON. NOV, HE ARE GOING TO DISCUSS SYSTEMS IN WHICH
THE SOUND
EFFECTS ARE RECORDED ON A STRIP OF PHOTOGFZAPHIC FILM; THE SAME
AS THE
PICTURE ITSELF; SO THAT NO DISC RECORD IS REQUIRED‘
I
we
GENERALLY REFER TO THIS METHOD ‘
or souuo
RECORDING AS "Souuo-ON-F|LM" ‘
OR SIMPLY
"FILM RECORDING". Two POPULAR
svsvzns
EMPLOYING THIS METHOD ARE THE
WESTERN
ELECTRIC ("Mov|:ToNE") AND THE
R.C.A.
("Pnoropuows "). ALTHOUGHBOTH
or THESE
svsrsms RECORD THE souuo on
FILM, YET
THE PROCESSES INVOLVED av
EACH ARE
DIFFERENT. THEREFORE, THESE
Two SYSTEMS
v|LLBE DESCRIBED SEPARATELY
IN THIS
LESSON.
HOWEVER,
BEFORE GOING INTO THE
DETAILED
o|scuss|ou or EITHER or wuss:
svsrsns, IT
us ADVISABLE THAT YOU FIRST
BECOME
FAMILIAR HITH A u~\1, WITHOUT
HHICH
NEITHER SOUND—ON—FlLM NOR TELE-
VISION
WOULD as POSSIBLE. THE uunr IN
QUESTION |s
THE PHOTO-ELECTRIC CELL.
BY sruovunc
ITS coustaucruon AND OPER-
ATION AT
THE azcuunune OF runs Lesson,
YOU HILL
READILY UNDERSTAND ITS APPLI-
CATION TO
souuo PICTURES AS vz PROGRESS F|e.
warn THE
INSTRUCTION. Sruozuts WORKING on PROJECTOR
PAGE 2
SOUND
PICTURES
PHOTO-ELECTRIC
CELLS
Two
D|FFERENl TYPES or :HoTo-ELEcTR|c cELLs ARE SHOWN |~ FIs.2 AND
THE SYMBOL
FOR THE PHoTo~cELL, AS IT IS FREQUENTLY CALLED, as SHOWN IN
THE LOWER
PORTION OF FIG-2- THE CELL
THE ACTIVE
OR LIGHT—SENSITlVE MATERIAL
PLIED T0 A
METALLIC COATING ON THE INNER SURFACE OF THE
FORMING THE
CATHODE.
AT THE LEFT
IS KNOWN As THE "V|s|-
TRON"
PHOTO—ELECTRIC CELL AND nu
THIS cAsE,
THE CATHODE CONSISTS or
A CONCAVE
METAL SURFACE upon WHICH
A
LIGHT—SENS|T1VE MATERIAL IS DE-
POSITED AND
THE ANODE |s |~ THE
FORM OF
A,CENTRALLY LOCATED WIRE.
BoTH or
THEsE ELEMENTS ARE sEALEo
WITHIN A
GLASS EuLE,wH|cH IN SOME
cAsEs
|5'EVACUATED HH|LE IN OTHER
cAsEs BEING
FILLED WITH some INERT
sAs, SUCH
As HELIUM, AHsoH,oR NEON
AT Low
PRESSURE. CELLs OF THE LATI
ER TYPE ARE
GENERALLY REFERRED To
As BEING or
THE GAS—F|LLED TYPE.
FH0H ITS
OUTER APPEARA~cE,TH|s PH2
TO-CELL
SOMEWHAT RESEMBLES A RADIO
TUBE.
THE
PHOTO-CELL AT THE RIGHT
OF F|e.2 |s
A "RAYTHEON" AND an
THIS
cAsE,THE SHAPE or THE GLASS
BULB IS
DIFFERENT AND THE ANQDE
TAKES THE
FORM OF A METALLIC RING.
IN THIS
RAYTHEON PHOTO—CELL as A5
cLAss BULB,
THUS
A CIRCULAR
PORTION OF THE GLASS, HOWEVER, IS LEFT CLEAR AND THIS
IS KNOWN AS
THE "WINDOW" AND THROUGH THIS TRANSPARENT-PORTION, WE PASS
A BEAM OF
LIGHT FROM THE OUTSIDE SOURCE- SO MUCH FOR THE CONSTRUCTION
OF
PHOT0—CELL$ —‘ NOW LET US CONTINUE WITH THE DISCUSSION CONCERNING
THEIR
OPERATION.
OPERATION
OF THE PHOTO-ELECTRIC CELL
In FIG-3 wE
HAVE A FUNDAMENTAL
PHOTO—ELECTRIC
CELL CIRCUIT AND As
vou WILL
NOTE, THE POSITIVE END or
A sATTERv
IS CONNECTED To THE ANODE
or THE
PHOTO-CELL THROUGH A H|cRoAH§
ETER AND
RESISTOR WHILE THE NEGATIVE
END or THE
BATTERY |s CONNECTED To
THE cATHouE
SURFACE or THE cELL. THE
ANODE or
THE CELL now connzspouos TO
THE PLATE
or AN ORDINARY RADIO TUBE
AND THE
CATHODE TAKES THE PLACE or
THE
FILAMENT on cATHonE or A RADIO
LESSON no.2
PAGE 3
In ALL
TYPES or RADIO Tuszs, WE nenznn uwon HEAT, IN ORDER TO OB-
TAIN AN
EEEcTnon EMISSION Ann THE HEAT IS FURNISHED BY A FILAMENT cunn-
znr. In THE
CASE OF THE PHOTO-CELL, wE HAvE no HEATING ELEMENT sul In
PLACE or
THIs,ELEcTR0ns ARE EMITTED FROM THE CATHODE DUE To THE EFFECTS
or LIGHT
RAYS STRIKING THE LIGHT-SENSITIVE SURFACE or THE cATHonE.
MANY
SUBSTANCES WILL EMIT ELECTRONS WHEN PLACED UNDER THE |NFLU~
ENCE OF
LIGHT BUT CERTAIN SUBSTANCES WILL EMIT MANY MORE ELECTRONS UN-
DER THESE
CONDITIONS THAN OTHERS. ALKALI METALS OR ALKAL|—METAL HYDRI-
DES ARE
QUITE SENSITIVE TO LIGHT RAYS AND AMONG THE MOST COMMONLY USED
ALKALI-METAL
HYDRIDES FOR PHOTO~CELL PURPOSES ARE SODIUM HYDRIDE,POTASS-
IUM HYDRIDE
AND CAESIUM HYDR|DE- THERE ARE STILL OTHER SUBSTANCES, WHICH
EXHIBIT
PRONOUNCED EFFECTS WHEN SUBJECTED TO LIGHT RAYS BUT THOSE MEN-
TIONED ARE
THE MOST EFFECTIVE MATERIALS, WHICH HAVE SEEN FOUND UP TO THE
PRESENT
TIME- WE SPEAK OF THESE SUBSTANCES A5 BEING "LIGHT SENSITIVE".
SHOULD THE
PHOTO-CELL OF FIG-3 BE PLA— sauna T?ack
I
CED IN
ToTAL DARKNE$5,THEN THE MICROAMMETER
WOULD
INDICATE no CURRENT FLOW BECAUSE no EL- ifia; ‘"”§g§;
ECTRONS ARE
BEING EMITTED FROM THE cATHonE = ‘
SURFACE-
Now IF A BEAM or LIGHT WERE To as
DIRECTED To
THE LIoHT~sEnsITIvE SURFACE or "
THE
cATHonE, A STREAM or ELECTRONS WILL as E-
MITTEP FROM
THIS SURFACE AND SINCE THE Anon: 3=<~;;§$£;;;;§C) I
Is AT A
POSITIVE POTENTIAL, nu: Tn THE BATT~ ;;; @?§§§§
ERY
CONNECTION, IT WILL ATTRACT THE EHITTEd §?*\'§§§§C3
ELECTRONS.THE
RESULT IS THAT we HAVE A STREAM _"=w _H+H
OF
ELEcTRoNs AT THIS TIHE FLOWING FROM THE j§§%a VEEECD
CATHODE
oven To THE ANODE Ann THEREFORE CURR- v __H_H
EnT wILL
FLOW THROUGH THE SYSTEM As INDICATED, ’I*.~~* ’“*““;3
K] UIU U U U U U O U U U U C
-1-:-I-I-I
‘Q-I-Ii‘-£ -£31-I-ii-I-I-I+Z-I-I-IT.‘-I-I
I-I'-Z£‘-I-J-I*I-Z-I-I'I-Ii-I-I
_ ‘
THE SAME As
PLATE CURRENT FLOWS THROUGH THE $fi¢é%;A§;§§§;c3
CONVENTIONAL
RADIO TUBE. ' I?
_»‘~;:a_
IF THE
LIGHT BEAM Is INTENSIFIED, THEN §§§; _§ §§§C>
THERE WILL
BE An INCREASED ELECTRON EMISSION ‘*§§§f\ §g§§§§
rnom THE
cATHonE, ACCOMPANIED wITH A CORRE5- Dflv¢'T?acg”{‘
PONDING
INCREASE IN THE so CALLED "PLAT: cunn , ,
V H if
—
EHT"
on PHOTO-CELL CURRENT; ThUS'IT Is SEEN FIG 4
THAT THE
CURRENT FLOW WILL VARY As THE |NTEN- S¢=£kn o a Him as uszd
SITY OF
LIGHT, wHIcH Is rocuszn upon THE PHO- 01 Eh: Amwkfane Qfl/am.
To-cELL
VARIES.
THE
PHOTO—CELL CAN as COMPARED vsnv NICELY To A MICROPHONE, FORTHE
MICROPHONE
cHAncEs AIR PRESSURE VARIATIONS INTO ELECTRICAL CURRENT VAR-
IATIONS or
CORRESPONDING FREQUENCY, WHEREAS THE PHOTO-CELL CHANGES LIGHT
VARIATIONS
INTO ELEcTRIcAL CURRENT VARIATIONS or CORRESPONDING FREQUENCY
TH: CURRENT
THROUGH THE PHOTO—CELL Is so SMALL THAT IT IS MEASURED IN Hi
CROAMPERES
(H|LL|onTHs or An AHPERE).
GAS-FILLED
PHOTO-CELLS ARE MORE SENSITIVE THAn THE VACUUM TYPE-THE
REASON ron
THIS IS THAT THE PHOTO ELECTRONS IONIZE THE INERT sAs IN
THEIR
PASSAGE rnon THE CATHODE SURFACE ovzn To THE ANODE- THAT Is, THE
PHOTOELECTRONS
FLOW FROM THE CATHODE oven THE ANODE AT SUCH A TREMENDOUS
FAG‘ b
souuo PICTJRES
vELocITY,
THAT WHEN THEY COLLIEE wITH MOLECULES oF THE INERT GAE, TIFY
BREAK THEsE
MOLECULES up INTO THE ELECTRONS AND PROTONS or WHICH THET
ARE
COMPOSED- WE cALL THIs ACTION "IoNIzATIoH av coLLIsIoH". THESE EXTRA
ELECTRONS
ARE THEN ALso ATTRACTED To THE POSITIVELY CHARGED PLATE, IN
ADDITION To
THosE LIBERATED BY THE cATHooE AND THE RESULT I5 THAT THE
PHOT0—ELECTR|C_CURRENT
IS INCREASED OVER wHAT IT WOULD BE wITH THE FLow
OF
PHOTO—ELECTRONS ALONE» (PHoToELEcTRoHs ARE THE ELECTRONS WHICH ARE E
MITTED FROM
THE CATHODE oF THE PHOTO-CELL AND THE PHOTO—ELECTR|C CURRENT
coRREsPoNbs'T0
THE BLATE CURRENT or AN ORDINARY RADIO Tuss.)
NoT ONLY Is
THE PHOTO-ELECTRIC CURRENT AFFECTED av THE INTENSITY
oF THE
LIGHT DIRECTED uPo~ |Ts cATHooE SURFACE BUT A CHANGE IN THE PO-
TENTIAL
APPLIED To THE AHo0E WILL ALso PRODUCE A PRONOUNCED EFFEcT UPON
THIs
CURRENT.
THE WESTERN
ELECTRIC SYSTEM
Now LET us
TURN OUR ATTENTION To THE WESTERN ELEcTRIc SYSTEM oF
PRODUCING
souno PICTURES. IN FIs.h, YOU ARE sHowH A PIECE 0F FILM AS us
' 0 1 brages
DUE To THE DARK AND
LIGHT
SHADING, SIMILAR
To THAT
WHEN YOU HOLD
A NEGATIVE
CAMERA FILM
FIG'5
AGAINST A LIGHT.
T/2: L/qhé
I/a/we far Maw/'eian¢ Pecan!’/‘n9.
A
CONTINUOUS Row
0F EQUALLY
sPAcEo NOTCHES ARE LocATEo ALONG EAcH EDGE oF THE FILM As
SHOWN IN
FIe.h. WE HAVE LABELED THIs As THE“0RIvE TRAcK"aEcAusE SPROCK-
ET coes
MESH WITH THEsE HoLEs, so As To PULL THE FILM THROUGH THE PROJE£
TOR.
AHQTHER
NARROW sTRIP Is INCLUDED BETWEEN THE PICTURE STRIP AND THE
LEFT DRIVE
TRACK AND THIs IS THE SOUND TRACK. THE souwn TRACK CONSISTS
0F A
LADDER—L|KE BAND or sHALL LINES AND THIS Is THE FILM souno RECORD.
As YOU wILL
NOTE, THEsE TINY LINES IN THE souuo TRACK ARE or CONSTANT
WIDTH BUT
THE DENSITY VARIES , THAT Is, SOME PORTIONS ARE BARKER THAN
oTHERs.
THE PITCH
OF THESE FILM RECORDED SOUNDS IS REPRESENTED BY THE NUM-
BER OF
CHANGES FROM DARK TD LIGHT AND BACK AGAIN IN A GIVEN LENGTH OFTHE
LESSON no.2
PAGE 5
SOUND
TRACK, WHILE THE DIFFERENCES IN THE INTENSITY OF SOUND ARE REPRE-
SENTED BY
THE DIFFERENCES IN THE DENSITY OF LIGHT AND SHADE ALONG THE
SOUND
TRACK- SINCE THE SOUND RECORD IN THIS CASE IS AN ACTUAL PART OF
THE
FILM’SYNCHRONIZATION BETWEEN SOUND AND SCENE PRESENTS NO PROBLEM IN
THIS
SYSTEM, BECAUSE THE RELATION BETWEEN THE SOUND TRACK AND THE FILM
IS
PERMANENTLY FIXED.
THE SECTION
OF FILM IN FIG. H REPRESENTS A FINISHED FILM, READY TO
BE RUN
THROUGH A PROJECTOR BUT BEFORE WE CONSIDER THIS PART OF THE SUB-
JECT;'YDU
W1LL OF COURSE FIRST WANT TO KNOW HOW THE SOUND ON FILM IS OR-
IGINALLY
RECORDED.
THE
MICROPHONE PICKUP, MONITORING.AND AMPLIFICATION OF THE AUDIO
FREQUENCIES
IS TAKEN CARE OF IN THE WESTERN ELECTRIC SYSTEM IN THE SAME
wAv As
DESCRIBED RELATIVE
To THE
VITAPHONE on DISC R5
CORDING
SYSTEM or THE PRE-
wous
LESSON. Tn: MAJOR oy-
FFERENCE
BETWEEN THESE Two
souuo
naconouus SYSTEMS rs
rouuo AT
THE RECORDING UNIT
ITSELF.
THE LIGHT
VALVE
IN PLACE or
THE CUTT-
vuo DEVICE
or THE VITAPHONE
sYsT:M,A
LIGHT VALVE IS us-
co ron THE
souno RECORDING
av THE
WESTERN ELECTRIC pno
L ml,”
VALVE is SHOWN IN I,-|G_ C'o/1/1:c£/"nu Befween L/5/:25 /a/vg and Am/-v/.
5. Tans
ozvncz CONSISTS or DURALUMIN TApz 0.006" wnoz AND 0.003" THICK,
WHICH |s
SHAPED INTO AN OBLONG LOOP AND suspsnozo an A PLANE AT RIGHT AN
oL:s-To A MAGNETIC
FIELD.
Tu: anus or
THE TAPE ARE szcunso AT THE WINDLASSES A5 SHOWN |N
F|o.5 AND
IT |s STRETCHED TIGHT av A SPRING-HELD PULLEY ovzn WHICH THE
Loop |s
pAsszo. A PAIR or INSULATED PINCERS co~p|u: THE CENTRAL ponrnous
or THE TAPE
azrwczu THE w|NoLAss:s AND PULLEY so As To FORM A SLIT op
SPACE or
0.002" BETWEEN THE Two SIDES or THE Loop AT THIS POlNT.$UPPORT-
nus THIS
Loop AND THE ADJUSTING DEVICES IS A METAL SLAB WITH A CENTRAL
ELEVATION,
wnncn CONSTITUTES THE ARMATURE or AN ELECTROMAGNET. Tn: CEN-
TRAL
PORTIONS OF THE DURALUMIN LOOP ARE SUPPORTED on INSULATING BRIDGES
JUST ABOVE
THE FACE or THE ARMATURE AND HERE THE snnzs or THE Loop ARE
cznrsnzu
oven A TAPERED sLoT.
Tn: Two
SIDES AT THE CENTRAL PORTION or THE LOOP CONSTITUTE A sL|T
0.002"
HIDE BY 0.256" Lone, WITH ITS snocs LYING IN A PLANE AT RIGHT AN-
GLES TO THE
LINES or ropcs AND APPROXIMATELY czurzpzo an THE AIR GAP-THE
suns or THE
Loop ARE CONNECTED To THE ouTpuT TERMINALS or THE RECORDING
AMPLIFIER
AS'SHOVN an F|o.6,wneR: THE LIGHT VALVE as ILLUSTRATED To ex-
AGGERATED
PROPORTIONS FOR THE SAKE or CLEARANCE- Ir THE MAGNET as znqg
onzzn AND
THE AMPLIFIER PASSES AN AUDIO rpzousucv CURRENT THROUGH THE
[AGE 6
souno PICTURES
Loop, Tuen
Tue LOOP w|LL open on spReAu APART Ann AGAIN cLose |n AccoR-
oAnce w|Tu
Tue CURRENT vAR|ATzon THROUGH IT. NOTICE |n F|o.6TuAT we uAve
NOT
INCLUDED Tue MONITOR on OTHER ACCESSORIES Ano JUST Tue BACK—BONE or
THE svsreu
I5-SHOWN FOR Tue SAKE or s|uPL|c|TY.|r A BEAM or LIGHT as 0|-
RECTED AT
Tue CENTRAL PORTION or THE Loop,wueRe we uAve Tue NORMAL sepA5
AT!0N or
.O02",|T as oav|ous TuAT Tue LIGHT BEAM pAss|nc THROUGH THIS R5
STRICTION
w|LL ae MADE wuoep Ano NARROWER Acc0R0|Ns To Tue openane Ano
CLOSING or
Tue Loop. Fon THIS REASON,IT IS CLEAR wuv THIS oevnce as cALL
eo A
"LIGHT vALve".
Wuen one
5105 or THE AUDIO wAve opens Tue vALve To 0.00M" Ann Tue
OTHER s|ne
cLoses IT coupLeTeLY, THEN FULL MODULATION or Tue APERTURE
on OPENING
ms AccoupL|sueo. Tue NATURAL eneouencv or Tue vALve |s seT av
ADJUSTING
Tue TENSION or Tue TApe Ano expeulence uAs suown TuAT sesr RE-
SULTS ARE
osTA|neo av TUNING Tu|s LIGHT vALve To A epeouencv or 7000 cv-
CLES pen
secono. Unoen Tuese cono|T|ons, ABOUT 10 MILLIWATTS or powep
ARE
REQUIRED eon FULL MODULATION AT FREQUENCIES FAR AwAv epou RESONANCE
BUT ONLY
AaouT 1/100 or THIS powep |s REQUIRED AT THE RESONANT FREQUENCY.
SOUND
RECORDING WITH THE WESTERN ELECTRIC SYSTEM
Tue nexT
5TEP rs To see uow Tu|s LIGHT vALve IS useo IN Tue necogg
ING or
souno F|LM- A
Source. of
Fi\I'Y\
. _ _ , _ M
F SIMPLIFIED DIAGRAM oe
Inqhlz
Lsqhk beam Lxqhfi valve
ta? THE WESYERN ELECTFHC
_ souno
RECORDING peo-
,— \\ /,-
\\\ cess |s suown |n FIG-
— _ “ _ “*;
Ymiqe Y AND eon THE PRESENT
’/ \ // . 1
T’ \\ -/ °€
hqht we suALL DEAL ONLY
Ia‘.
// \\
valve
Bwrwez WITH
Tuose essenT|AL
.;.-Am,
Condensing line _ ‘ PARTS ueue ILLUSTRATED
-.f*l:;;;;,5{ Ob5z=l:|\/e Ens ‘
_.-
_=l , .
_ AT
Tue LEFT or
F1s.7, we
uAve oun
Mnmghgng
Ampufier _ soufice or Lrcur rn THE
F‘6 7 eonu
or A RI8BON—FlLA—
M°"’“*°”Z
p’°C“$ 5/ 5:’“””/ ‘*'¢*?- MENT TYPE ppooecnon
LAMP Ann
THIS rs FOCUSED upon Tue VARIABLE sL1T or THE LIGHT vALve av
ueAns or A
conoens|ns Lens SYSTEM.
_4__‘~I'
/4’
\
/
/
Qo
"\
-—?_-Y
Assuu|no
eon Tue PRESENT TuAT Tue necopovno AMPLIFIER IS nor YET
|n
OPERATION, Tue SLIT or Tue LIGHT vALve w|LL pAss A ~ABEAH~ or 't4GHT,
wu|cu IS
0.002" w|oE Ano 0.256" LONG Ann THIS |s DIRECTED upon An OBJEC-
TIVE Lens ,
wurcu on TURN FOCUSES THIS seAu WITH A Two-To-one REDUCTION
upon Tue
PHOTOGRAPHIC FILM AT THE FAR RIGHT. Tue openans or Tue LIGHT
vALve now
APPEARS on THE FILM HALF—SlZE op As A LINE 0.001" wcoe Ano
0.128"
LONG, WITH ITS LencTu ee|ne AT RIGHT ANGLES To Tue DIRECTION or
FILM
TRAveL.
Now IF Tue
uncnopuone CURRENTS ARE AMPLIFIED Ano penurrreo To ACT-
uATe Tue
Loop |n Tue LIGHT vALve, THE WIDTH or Tue LIGHT vALve opennno
w|LL VARY
AT AUDIO FREQUENCIES Ann Tue SYSTEM |s Tuus ae|ns uoouLATeo.
Tue LIGHT
vALve |s now OPERATING As A CAMERA SHUTTER Ano Tue w|oTu oe
LESSON NO-2
PAGE Y
THE LIGHT
LINE UPON THE FILM WILL VARY WITH THE souuo cuRHEHTs,wI-IIEH ARE
SUPPLIED TO
THE vALvE. IN THIS WAY, THE FILM RECEIVES EXPOSURE TO LIGHT
or FIXED
INTENSITY BUT oumms THE VARYING TIME REQUIRED FOR A GIVEN
POINT or:
THE FILM T0 PASS THE VARYING OPENING or THE LIGHT VALVE sLIT.
THIS BEING
THE CASE, WE FIND THAT AS THE FILM MOVES PAST THE FOCUE
ING POINT
OF THE OBJECTIVE LENS, THE CONDENSATIONS AND RAREFACTIONS OF
THE
ORIGINAL SOUND WAVES WILL BE RECORDED AS LIGHT AND DARK VARIATIONS,
DUE TO THE
CORRESPONDING VARIATION IN EXPOSURE OF THE FILM T0 LIGHT AS
CAUSED BY
THE vALvE. '
Dunms TH_E
FILMING OF A PICTURE, THE souuu Is RECORDED on A FILM
SEPARATE
FROM THAT WHICH RECEIVES THE PlCTURE- TI-IIs PERMITS THE us: oF
TWO
MACHINES, so THAT DUPLICATE souno RECORDS CAN BE MADE AND CONSEQUEN-
TLY, IF ONE
SHOULD BE DEFECTIVE FOR SOME REASON OR OTHER, THE szcouo
WILL COME
IN MIGHTY HANDY- ANOTHER IMPORTANT REASON FOR HAVING SEPARATE
NEGATIVES
FOR souuo AND PICTURE Is
THAT THIS
PRACTICE PERMITS A SEPAR- Ron cf Wm A,
ATE AND
SPECIAL DEVELOPING PROCEDURE
FOR EAcH.
THIs Is ESPECIALLY DESlR- Lamphouse \~
AEILE WITH
RESPECT To THE Souuo FILM Gears Mcrrar
BECAUSE IT
IS NECESSARY THAT THIS I E;¢Id<@1I \ /
L;
FILM as
DEVELOPED To UNIFORM |NTEN- V;I,,¢ \»
SITY
THROUGHOUT ITs ENTIRE LENGTH, \ ' ‘ T‘ ' ~’ T“ _
IN omen To
PROVIDE PROPER s0uNu PRO— . 39, gfl " '3 I);-
DRIVEN IN
PERFECT SYNCHRONISM WITH
JECTION.
M_'*’ ‘\_
_ Inf __
"bi ,
I 4 1 /
_ _ . E_- _
_ '
,, .
= , » ._ -
_
TI-IE souun
RECORDING MACHINE Is C,
THE CAMERA
AND TD INSURE AGAINST ANY
VARIATION
IN THE VELOCITY or THE
souuu FILM
PAST THE LINE or LIGHT EX- 1 ’ I
PosuRE, THE
SPROCKET WHICH CARRIES Fqgm
THE FILM AT
THAT POINT IS DRIVEN THRU
A
MECHANICAL FILTER, WHICH HOLDS TI-IE
INSTANTANEOUS
VELOCITY CONSTANT TO F16. 5
ONE PART IN
ONE THOUSAND. M,,,/,'¢,_¢Q,,¢ 5,”,-,4 ,2gwm/=r:
IN FIG- 8,
YOU WILL SEE SUCH A RECORDING MACHINE, WITH THE DOOR OF
THE
EXPOSURE CHAMBER OPENED SO THAT THE INNER CONSTRUCTION CAN BE OBSER-
{EO- IN
ORDER THAT THE OPERATORS OF THE RECORDING EQUIPMENT MAY KNOW THE
QUALITY OF
THE RECORDING DURING THE TIME IT IS BEING MADE, A SOUND PICK-
UP DEVICE
IS INCORPORATED WITHIN THE RECORDING MACHINE. IN THIS WAY, THE
SOUNDS CAN
BE REPRODUCED DIRECTLY AS THEY ARE BEING RECORDED.
THE PICK-UP
DEVICE FOR SOUND REPRODUCTION
THIs
PICK-UP DEVICE CONSISTS OF A PI-IoTo-cELL, WHICH Is MOUNTED
WITHIN THE
EXPOSURE CHAMBER OF THE RECORDING MACHINE BEHIND THE LEFT
HAND
SPROCKET As VIEWED IN I-'Is.8. FREsH FILM TRANSMITS ABOUT II% or THE
LIGHT wHIcH
STRIKES IT AND so THE BEAM 0F LIGHT PENETRATES THE FILM AS
SHOWN IN
FIa.9 AND ENTERS THE wnwow _OF THIS PHOTO-CELL.
THE AMOUNT
OF LIGHT, WHICH ACTS UPON THE LlGHT—SENSITIVE MATERIAL
PAGE 8
SOUND
PICTURES
OF THE
PHOTO CELL,WlLL BE DETERMINED BY THE DENSITY OF THE PORTION OF
THE SOUND
TRACK,WHlCH HAPPENS TO OBSTRUCT THE PATH OF THIS LIGHT BEAM AT
ANY ONE
INSTANT- THEREFORE, THE INTENSITY OF THE LIGHT ACTING UPON THE
PHOTO-CELL
WILL VARY IN DIRECT PROPORTION TO THE LIGHT AND I DARK POR-
TIONS ON
THE FILM SOUND TRACK AND SINCE THESE ARE DISTRIBUTED ACCORDING
/0 /nay.
v'~<
§Q\.
I'|'l'|'
TO AUDIO
FREQUENCIES, THE LIGHT BEAM ACTING upon THE PHOTO-CELL WILL
Mcfian ii / }q\m Condenicr rneouzucv.
cf f1: 7 Tub:
6¢-
Ph°£°_GeH THE ELECTRON sn|s-
Ey ~ SION
FROM THE PHOT0—CELL'S
_ /, /) §
CATHODE WILL INCREASE AND
L"3I‘t
j , '. 5 DECREASE IN PROPORTION 1'0
b“""\' I I N ‘ rues: VARIATIONS IN LIGHT
"I
INTENSITY,VlTH was RESULT
THAT THE
PHOTO-CELL cunn-
__ ENT noes
LIKEWISE. Tnus
““' av
HAVING A VARIATION or
F|e.9
Man
/for//15 P/10/'0 - ce// P/2k — up .
VARY AT A
CORRESPONDING
PHOTO-CELL
cuansur FLOWING
THROUGH THE
2 MEGHOM a:s|§
TOR OF
FIG-9,SIGNAL VOLTA-
sss or
connzspononue raz-
QUENCY_ARE
DEVELOPED ACROSS THIS RESISTOR AND THESE SIGNAL POTENTIALS
ACT THROUGH
THE FIXED CONDENSER AND IMPRESS THEMSELVES ACROSS THE GRID
CIRCUIT OF
THE AMPLIFYING TUBE-
Tnssz AUDIO
SIGNALS, wnsu APPLIED TO THE GRID CIRCUIT OF THE AMPLI
FYTNG Tuai,
uwosaso CONVENTIONAL A.F. AMPLIFICATION A~u’av ADDING ADDI-
TIDNAL
AMPLIFYING STAGES, THE SIGNAL ENERGY CAN as RAISED TO A SUFFICIEN
TLY HIGH
LEVEL SO AS T0 OPERATE A SPEAKER IN THE CONVENTIONAL MANNER.
THE SPEAKER
IN THIS CASE IS IN THE MONITORING ROOM,THE PRELIMINARY
AMPLIFIER
or F|c.9 |s LOCATED asnow THE
EXPOSURE
CHAMBER or THE RECORDING MACHINE,
AND tn:
ADDITIONAL AMPLlfIER |s one SEPAR-
ATE FROM
‘run some THE REGULAR RECORDING
AMPLIFICATION.
RECORDING
PRACTICE
In sTu0|o
PRODUCTION,THE MIXER open-
ATOR as
STATIONED |u THE MONITORING ROOM
AND HE
vlzws THE "szr" (STAGE SET-UP) THRU
A DOUBLE
w|uoow nu THE sTuu|o WALL AND nu
ADDITION TO
OPERATING rue MIXER PANEL ron
COMBINING
THE cournnaurnous or SEVERAL un-
CROPHDNE5,
HE ALSO CONTROLS THE GAIN OFTHE
AMPLIFIERS
ron THE RECORDING MACHINES.
BY MEANS OF
RELAY SVlTCHES,THE MIXER
OPERATOR
CAN CONNECT THE MONITORING HORN
CIRCUIT
EITHER DIRECTLY TO THE RECORDING
AMPLIFIER,
AS WAS SHOWN YOU RELATIVE TO Vi
LESSON No.2
PAGE 9
TAPHONE OR
DISC RECORDING IN THE PREVIOUS LESSON, OR ELSE HE CAN CONNECT
THE HORN
CIRCUIT TO ONE OR THE OTHER OF THE PHOTO-CELL PICK UP CIRCUITS
WHICH WAS
DESCRIBED A FEW MOMENTS AGO-
1
DURING THE
TIME THAT PRELIMINARY TESTS ARE BEING CARRIED OUT SO AS
TO
DETERMINE THE BEST MIQROPHONE POSITION ON THE SET ETC., THE MONITOR-
ING HORN
CIRCUIT IS CONNECTED DIRECTLY TO THE OUTPUT END OF THE RECORD—
ING
AMPLIFIER. THE PROGRAM IS THEN REHEARSED ON THE SET UNTIL A SATISFAC
TORY
ARRANGEMENT OF THE MICROPHONES AND OF AMPLIFIER GAIN IS DETERMINED-
TH:
ELECTRICAL cHARA¢T:HIsTIc or THIs MONITORING CIRCUIT IS so 0:-
SIGNED THAT
TH: souun QUALITY HEARD IN TH: MONITORING HORNS sHALL a: TH:
SAME As TH:
QUALITY To s: EXPECTED
IN THE
REPRODUCTION 0F TH: POSI-
TIv: PRINT
IN TH: TH:AT:R. TH:
wALLs or
TH: MONITORING ROOM ARE A
cousTIcALLv
TREATED IN SUCH A wAT
THAT ITS
REVERBERATION CHARACTER-
IsTIcs WILL
a: THE SAME AS THAT IN
TH: THEATER
AND TH: MONITORING LE1
:L Is so
ADJUSTED THAT TH: MIXER
OPERATOR
HEARS TH: SAME LOUDNESS
THAT H:
wouLo wIsH To HEAR rnom
THE THEATER
HORNS. IT Is VERY IM-
PORTANT
THAT TH: OPERATOR JUDGE
HIs PICK-UP
on TH: BASIS or souND
cLos:LY
IDENTICAL IN LOUDNESS AND
QUALITY yITH
THAT To as H:AHo LAT-
ER IN
THEATER REPRODUCTION.
P201: cTcw.
BO‘
u>~uT
- '1'uT;uTAlI..!
WITH
EVERYTHING ADJUSTED To
TH: POINT
DESIRED, TH: OUTPUT or
TH:
RECORDING AMPLIFIER IS DISCON-
NECTED FROM
TH: MONITORING HORNS
AND Is How
CONNECTED To TH: LIGHT
vALv:s or
TH: RECORDING MACHINES
AND TH:
MONITORING HORNS ARE CONN- Pied] -
:2*::;:I:::;::*:.:::;Ls""Iii:
A W
no FILM IN
TH: MACHINE AND AT, A 0'5‘ a”J Eb” E'C°r°6”9'
CONVENIENT
LAMP CURRENT, A COMPLETE REHEARSAL Is MADE so As To VERIFY
TH:
OPERATION or TH: LIGHT vALv:s AT TH: PROPER L:v:L. FILH Is TH:~ LoA3
:0, TH:
CAMERAS AND souuo H:¢onn:Rs ARE INTERLOCKED AND STARTING MARKS
ARE MADE on
ALL FILMS EITHER av MEANS or PUNCHES OR ELSE WITH FLASHES or
LIGHT upon
TH: STARTING POINT or TH: FILM.
MAGAIIME
THE STUDIO
AND RECORDING ROOM SIGNAL TO EACHOTHER BY MEANS OF
LIGHTS AND
SO WHEN THE RECORDING EQUIPMENT IS READY FOR ACT|ON,THE REC-ORE
ING ROOM
WARNS THE STUDIO BY MEANS OF A LIGHT SIGNAL~ THE LIGHTING EFF‘
ECTS ON THE
STAGE ARE THEN PUT INTO OPERATION AND THE STUDIO THEN SIG-
NALS BACK
ITS READINESS TO START-
THE MACHINE
OPERATORS START THE CAMERAS AND SOUND RECORDERS,BRING—
I um.
M;;;u.~= ‘
I 1
Two INTO A
SINGLE rTLH,wTTH THE
souno TRACK
RUNNING ALONG THE
EDGE OF THE
PICTURE PORTION OF
THE FILM As
SHOWN IN FTs.h. In
PRINTING
THE souun NEGATIVES |~
COMBINATION
WITH PICTURES FOR
PROJECTION
IN THE THEATEn,|T IS
CUSTOMARY
TO FIRST PRINT THE
P4CIUR£~NEGATI¥E,MA$KING
(Cc¥ER;
ING) THE
sPAcE NEEDED FOR THE
souuo TRACK
Ana To RUN THE RE-
SULTING PICTURE
POSITIVE _THRU
THE PRINTER
AGAlN,TOGETHER WITH
THE souuu
~EsAT|vE,TH1s TIME
MASKING THE
SPACE ALREADY PRIN-
TED. In
PRINTING THE sou~o ~E§
AT|vE,THE
LIGHT IS REGULATED TO
RESULT"1N
35% TRAHsH1ssion or
THE
UNMODULATED TRACK AFTER Pqg
ITIVE
DEVELOPMENT-
UPON
COMBINING THE souno
TRACK w|TH
PICTURES UPON A
SINGLE
E|LH,THE souno RECORDING
AT THE SIDE
OF ANY one PARTICU-
LAR PICTURE
FRAME DOES NOT con;
ESPOND To
THE ACCOMPANYING PIC-
TURE. To
|LLusTRATE TH|s, STUDY
Frs.IO
CAREFULLY AND YOU WILL
NOTE THAT WE
HAVE LABELED ONE
or THE
PICTURE FRAMES (A). THE
souuo
Rsconouue T0 CORRESPOND
w|TH FRAME
(A) IS AT THE POINT WHICH |s LABELED (A). BETWEEN THEM THERE
as A
SEPARATION OF 19 PICTURE FRAMES DR IU.5".
THE REASON
FOR USING SUCH AN ARRANGEMENT IS THAT IN THE THEATER
PROJECTOR,
THE souun GATE |s LocATE0 IH.5" aELow THE PICTURE sATE,|N OR-
DER To
PROJECT THE souun RECORDING AT A POINT WHERE THE FILM IS IN cou-
TINUOUS
MOTION. TH|s WILL BE SHOWN MORE CLEARLY DURING oun o|scussao~ or
PROJECTION
v:TH THE MOVIETONE SYSTEM.
THE MOTION
PICTURE PROJECTOR FOR SOUND ON FILM
IN FTe.11,
YOU w|LL sEE A MOTION PICTURE PROJECTORJWHICH-IS EQUIP-
LESSON NO.2
PAGE II
PED FOR
BOTH SOUND ON DISC REPRODUCTION, AS WELL AS FOR THE REPRODUCTION
OF SOUND ON
FILM- THE INNER CONSTRUCTION or THIS sAME PROJECTOR Is SHOWN
IN F|G.12.
BY
REFERRING To FIG.I2, You WILL sEE THAT TI-IE FILM Is THREADED
FROM THE
UPPER MAGAZINE PAST THE PICTURE PROJECTOR LENS AND THENCE PAST
THE souuo
FILM LENS UNIT AND INTO THE LOWER MAGAZINE. VARIOUS SPROCKETS
AND ROLLERS
ARE USED IN sucH AN ARRANGEMENT so THAT THE FILM IS FED THRU
THE MACHINE
AT A UNIFORM RATE AND uuocn PROPER TENSION.
NOTICE THAT
THE PICTURE LENS IS ABOVE THE SOUND FILM LENS,SO THAT
ANY POINT
OF THE FILM MUST PASS THE PICTURE PROJECTING LENS BEFORE ARR-
IVING AT
THE SOUND FILM LENS UNIT- OBVIOUSLY, THE SOUND RECORDING MUST
BE ADVANCED
AHEAD OF THE CORRESPONDING PICTURE F'RAMES,AS ALREADY DESCRIE
ED, SO THAT
3OUND REPRODUCTION WILL OCCUR SYNCHRONOUSLV WITH THE CORRES-
PONDING
PICTURE. E
PI1nI'o<ceII
F'Im A
A POWERFUL
LIGHT AND LENS SYSTEM PRO— APEFIZOFQ Plaflq
/
JECTS THE
PICTURE UPON THE SCREEN OF THE ' Lam
TI-IEATER,As
THE sounu EQUIPMENT REPRODUCES ‘ / P)
THE sounos
IN SPEAKERS LocATEo BEHIND THE ‘
A
SCREEN. ,
LZHS
souwo
REPRODUCTION Window A"'L“'“
CONSIDERING
THE SOUND PICK-UP DEVICE Lamp
or FIG.I2
IN GREATER I:IETAIL,wE sEE rII=IsT THE B F"-“N Lens I
"ExcITEI=
LAm>".TIIIs Is A SMALL INCANDESCENT S
LAMP, wmcu
HAS A RELATIVELY HIGH CURRENT ‘ 1
AND Low
VGLTAGE cAPAcITY,coI~IsuMING eETwEE~}2 '
‘
AND Y5
wATTs. THE CURRENT FOR LIGHTING THIS T ‘
FILAMENT
MUST EE A PURE DIRECT CURRENT BE- IA/M aP,,Iu,.e I
Windcvw
cAusE ANY
VARIATION IN THE CURRENT wILL Lani
cAusE A
CORRESPONDING CHANGE IN THE PMoTo-EL
EcTRIc CFLL
CURRENT. THAT Is, IF A 60 CYCLE L 5 f FIe@§ ,
A.C. SUPPLY
WERE USED FOR THIS LAMP,ITs FlL- ‘"5 17‘7”5 %f‘d '”
AMENT WOULD
cooL AND HEAT up ALTERNATELY AT Ah'7‘f°”e rbflbzgri
THE RATE or
I20 TIMES PER SECOND AND ALTHOUGH THESE CORRESPONDING VARIA-
TIONS IN
LIGHT INTENSITY WILL BE UNOTICEABLE TO THE HUMAN EYE, YET THEY
ARE READILY
DETECTED BY THE PHOTO-CELL, WITH THE RESULT THAT A I20 CYCLE
ROAR WOULD
BE EMITTED av THE sPEAKERs. In FAcT, EVEN THE ARMATURE RIPP-
LEs or A
D.C. GENERATOR ARE REPRODUCEO BY THE PHOTO-CELL, IF usEo As THE
FILAMENT
SUPPLY FOR THE EXCITER LAMP.BATTER|ES ARE THE SOLUTION To THIS
PROBLEM.
TI-IE NEXT
THING IS TO FOCUS THIS LIGHT OF THE EXCITER LAMP upon THE
souuo TRACK
or THE FILM AND THIS IS ACCOMPLISHED av THE souun FILM LENS
UNIT or
FIG.12.
TI-IE
DETAILS or sucu A LIGHT FOCUSING ARRANGEMENT ARE snovu IN FIG.
I}. Oun
OBJECT now IS To IMPRESS A sMALL SHARP RECTANGULAR SHAPED GEAM
or LIGHT
UPON THE sounn TRAcI< or THE FILM. THE EAsIEsT wAv 70 no THIS Is
ILLUSTRATED
AT "A" OF FIG.1}, WHERE wE HAVE AN "APERTURE PLATE" PLAcEo
" IN
‘wn
DTH IS CUT
IN THIS
BY MEANS or
A
SUITABLE
LENS, THE
LIGHT FROM
rue zxc|1cn
LAMP CAN as
rocuszo u-
PON THIS
SLIT AND ruus
PENETRATE
THE FILM
souno TRACK
IN rue
SHAPE or A
SMALL NARR-
ow
RECTANGLE-THIS M215
OD,HOWEVER,
|5 nor Pni
CTICAL BECAUSE
A SLIT
As
THISQWITH AN AREA
or ONLY
ABOUT 0.0001
So.
IN-,CANNOT as KEPT
FREE rnon
FOREIGN MArl
ER ron ANY
LENGTH or
run: wucn
PLACED CLOSE
AGAINST A
RAPIOLY HOV-
nne FILM.
Fon THE
REASON
MENTIONED,
THE svsrcm wAs IMPROVED TO THAT snown AT "B" or F|e.1}. In
runs cAs:,
THE APERTURE SLIT |s novso AwAY rnon ITS :xPos:u POSITION
NEAR THE
FILM, |r |s SEALED w|1u|u A LENS svsrzn, MADE CONSIDERABLY wng
an AND
LONGER AND THEN OPTICALLY REDUCED TO A LIGHT RECTANGLE or 0.001"X
0.1"
on tn: FILM av MEANS or THE svsrsn OF LENSES- Tuus tn: RESULT IS
THE SAME AS
OBTAINED AS WITH THE CLOSE~UP SLITSYSTEM BUT WITHOUT ITS DI§
ADVANTAGES-
THIS NARROW
BAND OF LIGHT, WHICH I5 THUS FOCUSED UPON THE FILM
SOUND
TRACK, WILL PENETRATE THE FILM AND THEN BE DIRECTED AGAINST THE
LIGHT-SENSITIVE
ELEMENT OF A PHOTO-EL ECTRIC CELL
AND THE
‘INTENSITY OF THIS LIGHT,WHICH IS PASSED
BY THE FILM
HILL OF COURSE BE GOVERNED BY THE DEN
SITY OF THE
SOUND TRACK,WH|CI-I I5 EXPOSED TD THE
L IGNT.
THl$
PHOTO-CELL us COUPLED To A Pncx-up AM-
PL|r|:R,As
ALREADY snowu YOU IN F:s.9 or rnrs
LESSON, AND
rnus THE PHOTO-CELL cunnzur HILL VARY
ACCORDING
to THE LIGHT AND DARK PORTIONS on tn:
rnnn souuo
TRACK- Iu 1n|s wAv, LIGHT VARIATIONS
or AUDIO
rneauencv ARE CHANGED '”iWTO ELECTRICAL
cuancur VARIATIONS
or connsspononns Fnzaucucv.
Tu:
FHDTO~CELL PICK—UP AMPLIFIER |s sausa-
ALLV
azrsnnza TO As A "Pzcn AMPLIFIER". THIS AMP-
LIFIER
USUALLY CONSISTS or rwo on THREE STAGES or
CASCADE
AMPL|FlCATION,USING VARIOUS TYPES OF sou:
LING, BUT
RESISTANCE-CAPACITY COUPLING PRODUCES
Sound
I:I'7c.L ‘;";:‘:;':
' /
LESSON no.2
PAGE 1}
THE BEST
REsuLTs. THE CURRENT usED FOR OPERATING THE PECK AMPLIFIER HDET
BE PURE D.C
, SUPPLIED EITHER av STORAGE BATTERIES DR DRY cELLs. DuE T0
THE FEEBLE
CURRENT FROM THE PHOTO—CELL, THE PECK AMPLIFIER HAS To MAGNI~
rv |T FROM
ABOUT 100 TO 200 T|MEs AND THEREFORE ANY VARIATION aw THE P0!
ER SUPPLY
FOR THIS AMPL|r|ER, NO MATTER How LITTLE, WILL BE REPRODUCEO
AT GREAT
VOLUME BY THE SPEAKERS.
Iw FIG. TH,
YOU WILL sEE THE LAYOUT FOR THE REPRODUCTION or souwa
FROM FILM.
Two PROJECTORS ARE REQUIRED IN THE PROJECTION sooTH,THE sAME
AS FDR DISC
RECORDINGS 0R EVEN FOR SILENT PICTURES FOR THAT MATTER. No-
TICE How
THE Exc|TER LAMPFOR EACH PROJECTOR IS SUPPLIED w|TH BATTERY FIL
AMENT CURRENT
AND How EAcH or THE PHOTO-CELLS FEEDS INTO A PEEK AMPLl-
FIER- BoTH
or THEsE PICK-UP AMPLIFIERS FEED INTO A EADER, THROUGH WHICH
THEIR
ENERGY PASSES INTO THE MAIN AMPL|F|ER. THE MAIN AMPLIFIER THEN RA§
SES THE
AMPLIFIED AuD|o CURRENTS THROUGH THE HUGE sPEAKERs,wH|cH ARE LO-
CATED
BEHIND THE SCREEN upon WHICH THE PICTURE |s BEING PROJECTED. THE
SOUND THUS
APPEARS TO THE AUDIENCE As COMING FROM THE REPRODUCTIONS on
THE SCREEN.
A MONITOR HORN IS LOCATED IN THE BOOTH FOR THE 0PERATOR'S
USE.
To Amp].
Lamp___}
THE FILM IS
RUN THROUGH THE Lhh£_¢°P :=;'t
PROJECTION
MACHINE AT THE RATE or ' / 1 K :
90 FT- PER
MINUTE AND |T IS ESSEN- M;"Or <1 _ W '5;
TIAL THAT
TH|s SPEED BE KEPT CON— i 45) A
sTA~T,As
oTHERw|sE THE PITCH OF _D~ ;u",_“
THE SOUND
WILL CHANGE IN THE sAME ‘Q’ _ _ ,<
MANNER As
WHEN THE sREEo or A F'HO§ ‘ D
OGRAPH
TURNTABLE vAR|Es.As A RuLE, S:fl;_/
A LARGE
FLYWHEEL IS DIRECTLY COUP- _
LED To THE
FILM FEED SPROCKET FOR mg: AP¢'*W? PF*¢§' ’f
THE PURPOSE
or INSURING A STEADY om“5"'!e“5
ROTATION or
THIS sRRocKET,so THAT ;|G_|g
THE FILM
WILL BE cARR|ED PAST THE
BEAM OF
LIGHT FROM THEExc»TER LAMP
AT A
CONSTANT SPEED-
Phnéo/:/mr/=
/€¢¢ara’/Hg Dc»/ice.
THE
PHOTOPHONE SYSTEM
Now LET us
TURN OUR ATTENTION To THE PHOTOPHONE SYsTEM or“ souno
RECORDING
ON FlLM- A SECTION or FILM, As usED ev TH|s svsTEM, IS SHOWN
IN F|c.15
AND As A wHoLE, IT IS QUITE s|M|LAR To THE Mov|EToNE FILM IN
THAT IT HAS
A SOUND TRACK rm CONJUNCTION WITH THE PICTURE sTR|R.THE PHOI
OPHONE
SOUND TRAEK, HowEvER, IS or THE CONSTANT DE~s|Tv,vAR|AELE w|DTH
TYPE AND
THE DEGREE OF SHADING |s THE sAME BUT A VARIABLE PORTION OF THE
souuu TRACK
IS DARKENED.
|N
PRODUCING A PICTURE WITH THE PHoToPHoHE SYSTEM, THE MICROPHONE
PICK-UP,
MONITORING, AMPLIFYING ETC- |s ALL CARRIED OUT IN THE sAME MAN£
ER As WITH
EITHER DISC RECORDING OR Mov|ETo~E RECORDING. ALL or THEsE 51
STEMS
DIFFER FROM EACHOTHER MATMLY AT THE RECORDING DEv|cE ITSELF AND
THE
RECORD!NG UNIT, As usEo WITH PHoToRHo~E, as DIFFERENTFROM ANY so FAR
snow"
vou. THE PHoToPHoHE RECORDER I5 CLASSIFIED As A VARIABLE AREA RE-
CORDER AHD
IT IS DIAGRAMATICALLY ILLUSTRATED IN F|s.16.
fAsE IR
souno PICTURES
THE
RECORDING UNIT FOR THE PHOTOPHONE SYSTEM
WE coMMEncE
In FIs.16 WITH oun SOURCE oF LIaMT,wMIcM IN THIS cAsE
Is A LAMP OPERATED
AT HIGH BRILLIANCY FROM A 6 To 8 VOLT STORAGE BATT-
ERY. A
SPHERICAL LEns "A" FocusEs THIS BEAM or LIGHT THROUGH A MoLE In
THE
"LIGHT-STOP" WHICH SERVES As A FRAMING oEvIcE. TME BEAM or LIGMT,
WHICH
PASSES Tnnoucn THE OPENING oF THE LIGHT-STOP Is DIRECTED TOWARDS
ANOTHER
SPHERICAL LEns "B" Ano THIS LEns IN TURN FocusEs IT upon A
sMALL
MIRROR, wMosE DIMENSIONS ARE AsouT V20 or An INCH on A sIoE.
TMIs MIRROR
REFLECTS THE LIGHT BACK THROUGH LENS "B" AT An AncLE;
As snown av
THE Annows, Ann THE BEAM Is THEN DIRECTED THROUGH THE sno-
ovE or A
scALE uPon WHICH THE AMPLITuoE oF RECORDING cAn LATER BE MEAs-
uREo. THE
LIGHT BEAM CONTINUES THROUGH A CYLINDRICAL LENS "C",A SPHER
IcAL LENS
"D", Ano THENCE THROUGH A NARROW sLoT In THE APERTURE PLATE?
THE OBJECTIVE
LENS GENERALLY MAs A REDUCTION RATIO or U TO 1, so
’V&ra%r
ad_ £ L ITHAT IF TME_sLIT IN THE APER-
- J“‘
m="* TURE PLATE Is 0.320" av 0.00h",
Mfirc, TME IMAGE PRODUCED on TME FILM
a&uflHmn{ wILL as 0.080" av
O.O01".TMAT Is,
THIS sMALL
RECTANGLE or LIGHT u-
PON THE
FILM WILL BE 0.080" LONG
(HORIZONTALLY
wITM RESPECTTO THE
FILM) Ano
0.001" wIoE, Ano THIS
WILL
PRODUCE A souno TRACK 0.080"
wIoE, WHICH
Is cLosE To THE sTAn
DARD WIDTH
USED IN PRACTICE.
,_AUDJD,MODULAI!ON
WIT
1
P
m
x
H
I TME TInv
MIRROR Is cEMEn-
;|G ;7' TED
To Two sIoEs or A WIRE LOOP
,q,,,,',,y,,-,,,/,4qI,1,,-15,-r,¢,,;é;(,7/%/1¢@,¢,,,-,/a-
Ano THIS WIRE LOOP Is STRETCHED
TAuT AT
RIGHT AneLEs TO A MAG-
NETIC
FIELD. THE Enos or THIS LOOP ARE CONNECTED To THE OUTPUT TERMIN-
ALs or THE
RECORDING AMPLIFIER AND THEREFORE wMEn THE AuoIo FREQUENCY
CURRENTS
FLow THROUGH THE LOOP, THE RESULTING VARIATIONS In ITs MAGNET-
Ic FIELD
wILL REACT WITH THE PERMANENT MAGNETIC FIELo so As TO Faooucz
MoTIon. TME
MOVING PART In THIS cAsE Is THE WIRE LOOP wITM ITS ATTAcMEo
MIRROR AND
wITM TME LOOP TURNING BACK Ano FORTH on VIBRATING AsouT A
VERTICAL
AxIs In DIRECT STEP WITH THE AuoIo FREQUENCY CURRENT VARIA-
TIONS
THROUGH IT.
TME WIRE
LOOP Is STRETCHED TO TME POINT WHERE THE RESONANT VIBRA-
TING
FREQUENCY Is ABOUT 7000 cYcLEs. TMIs ENTIRE VIBRATING SYSTEM, con-
SISTING or
TME LOOP WITH ITs M|RfioR,
Is MOUNTED IN A cAsE CONTAINING A
DAMPING
FLuIo, wMIcM Is GENERALLY A MIXTURE or CASTOR OIL Ano TuRPEn#
TINE. TME
LENS "B" SERVES As THE wInnow 0F TME FLUID-FILLED CELL IN
wMIcM TME
MIRROR IS MounTEo Ano THE FLUID Is CHANGED EVERY FEw MonTMs,
so THAT IT
Is ALwAYs TRANSPARENT To THE LIGHT In THE THIN LAYER INTER-
POSED
aETwEEn THE MIRROR Ann LEns "B". In REALLITY,TMIs DEVICE IS no-
THING MORE
TMAn An oséILLocnAPM, WHICH Is A LABORATORY INSTRUMENT usEu
LESSON No.2
PAGE I5
FOR THE
RECORDING OF ALTERNATING CURRENTS-
THE
ARRANGEMENT I5 SLIGHTLY TILTED IN PRACTICE, so THAT THE LIGHT
REFLECTED
av THE MIRROR WILL CONTINUE ALONG THE AXIS TOWARD THE FILM As
SHOWN m
F|c-.16.
RECORDING WITH
PHOTOPHONE SYSTEM
THE WHOLE
SYSTEM IS LINED UP, SD THAT ONE EDGE OF THE HOLE IN THE
LIGHT STOP
IS IMAGED IN THE MIDDLE OF THE SOUND TRACK ON THE FILM WHEN
THERE IS NO
INPUT TO THE MICROPHONES AND WHEN THE MIRROR IS IN ITS NEU-
TRAL
POSITION. IF THE FILM IS MOVED PAST THIS RECTANGULAR BEAM OF LIGHT
AT A
CONSTANT SPEED OF 90 FT- PER MINUTE WITH NO SOUND IMPINGED UPON
THE
RECORDING MICROPHONE, THEN THE RESULTING RECORD AFTER OEVELOPEMENT
WOULD
APPEAR AS A DARK BAND ON THE SOUND NEGATIVE, COVERING HALF THE
WIDTH OF
THE sounu TRACK.
Now WHEN
THE H|cRoPHo~E,AH-
PLIFIER
ETc. ARE IN 0PERATION,THE
AUDIO
FREQUENCY CURRENTS WILLFLOW
THROUGH THE
WIRE LOOP, THEREBY
CAUSING THE
LOOP AND ITS ATTACHED
MIRROR To
OSCILLATE ow ITS PIVOT-
TH|s
MOVEMENT or THE MIRROR IS IN
DIRECT STEP
WITH THE AUDIO FRE-
QUENCY
CURRENTS FLOWING THRU THE
LOOP AND
THE MIRROR WILL DEFLECT
THE BEAM
RAPIDLY T0 ONE SIDE AND
THE
OTHER,THUS CAUSING THE LIGHT
IMAGE ou
THE FILM To VARY IN
WIDTH
ACCORDING To THE AUDIO FRE-
QUENCIE5
WHICH ARE aznwe RECORDED.
THAT us,
THE sounn TRACK WILL BE
OF VARIABLE
WIDTH As ILLUSTRATED 7Z= (Em /e/e ,4>-sem/S/ea @¢¢=»—d=r_
IN F|s.‘I§.
/0
FIG.15
THE HOUSING
AND ADJUSTMENT DETAILS FOR THE MOVEMENT,WHlCH REC-
ORDS THE
LIGHT VARIATIONS ON THE FILM, ARE SHOWN IN FIG-I7,WHEREA5 THE
MOVEMENT
AND ITS ASSOCIATED APPARATUS IN THE COMPLETELY ASSEMBLED Hecog
DER IS
snown IN F|a.18.
IT REQUIRES
SKILL TO ADJUST THE VARIABLE AREA TYPE OF RECORDER AS
JUST
DESCRIBED. THE WHOLE SYSTEM MUST
ATELY, SO
THAT THE BEAM OF LIGHT WILL
I6- THIS I5
ACCOMPLISHED THROUGH THE
BE LINED UP
AND FOCUSED ACCUR-
FOLLOW THE
PATHS INDICATED IN FIG-
USE OF A
SERIES OF ADJUSTING
SCREWS.
- THE WIRE
LOOP IS ROTATED BY ONE OF THESE ADJUSTMENTS AND IT IS
SET, SO
THAT THE LIGHT REFLECTED BY THE MIRROR COVERS JUST ONE-HALF OF
THE SOUND
TRACK- THE EDGE OF THIS LIGHT BEAM WILL THEN COINCIDE WITH AN
INNER
VERTICAL LINE ON THE SCALE, WHOSE POSITION IS SHOWN IN FIG. I6.
WITH THE
SYSTEM BEING MODULATED, THE AMPLIFIER GAIN MUST BE SO ADJUSTED
THAT WITH
THE MIRROR OSClLLATING’THE SPOT OF LIGHT SHOULD NOT EXTEND BE
PAGE I6
YOND
THEN
TONE
QUALITY-
THE SCALE
DURING THE LOUDEST PORTION or THE RECORDING- IF IT ooEs,
THE SYSTEM
Is BEING "ovER-MonuLATEn$ WHICH CONDITION HILL sPoIL THE
IN
RECORDING;THE PHOTOPHONE SYSTEM USES ONE MACHINE FOR PHOTOGRAPHY
AND A
SEPARATE MACHINE FOR SOUND RECORDING, EACH HAVING ITS OWN FILM BUT
BEING
SYNCHRONOUSLY DRIVEN. THE STARTING POINT OF EACH FILM IS MARKED;
AND THEY
ARE THEN COMBINED INTO ONE DURING THE DEVELOPING PRQCES5;IN THE
SAME MANNER
AS DESCRIBED RELATIVE TO THE MOVIETONE SYSTEM. HERE,TO0, THE
SOUND
PRECEDES THE PICTURE BY ABOUT IH.5 INCHES; SO THAT THE THO WILL BE
REPRODUCED
SIMULTANEOUSLY DURING PROJECTION OF THE FILM IN A THEATER.
IN THE
PROJECTION OF SOUND AND SCENE WITH THE PHOTOPHONE SYSTEM;THE
sAHE
PROCESSES ARE INVOLVEDAS DESCRIBED
THAT Is,
THE SAME PROJECTOR cAN BE USED
ENERGY
STRIKING THE PHOTO-CELL THROUGH
VARY IN
PROPORTION To THE WIDTH or THE
THEN, SINCE
THE HIQTH OF THE
AUDIO
FREQUENCIES, THE LIGHT
RESPONDING
FREQUENCIES; AND
CELL
CURRENT. THEREFORE, BY
SPEAKER
SYSTEM As USED HITH MovIEToNE,
RECORDING
FROM PHoToPHoNE FILM-
EXAMINATION
VARIATIONS
RELATIVETO
THE MOVIETONE SYSTEM.
FOR EITHER
SYSTEM, BUT THE LIGHT
THE
PHOTOPHONE SOUND TRACK, HILL
SOUND TRACK
AT ANY GIVEN POINT.
SOUND TRACK
VARIES ACCORDING TO THE RECORD
PASSED BY
IT WILL VARY AT COR-
THE SAME IS
TRUE VITH RESPECT TO THE PHOTO-
MEANS OF
THE SAME SOUND AMPLIFYING AND
HE CAN ALSO
REPRODUCE THE SOUND
QUESTIONS
LESSON NO.
SP-2
Ir A
BATTERY AND A SERIES RESISTOR ARE CONNECTED ACROSS
THE
TERMINALS or A PHOTO-ELECTRIC CELL so THAT A PosITIvE
POTENTIAL
Is IMPRESSED UPON THE ANooE or THIs PHOTO ELEC-
TRIC cELL,
THEN UHAT occuns IF A LIGHT or INCREASING
INTENSITY
Is DIRECTED UPON THE cATHonE or THE cELL?
WH|cH Is
MORE sENs|TIvE,A VACUUM TYPE PHOTO-ELECTRIC cELL
on A
GAS—FILLED PHoTo-ELEcTRIc EELL?
ls THE
SOUND TRACK ON THE MovIEToNE FILM or THE coNsTANT
DENSITY AND
VARIABLE HIuTH TYPE?
WHAT IS THE
PURPOSE or THE LIGHT vALvE IN THE MovIEToNE
RECORDING
SYSTEM?
WHAT IS THE
EXCITER LAMP or A “souNo-0N-PILH" PROJECTOR
uszo Fon?
WHEN MAKING
THE SOUND—0N—FlLM RECORDING; Is THE SOUND RE-
CORDED
DIRECTLY UPON THE sAHE FILM wHIcH Is RECEIVING THE
"PIcTuRE"?
WHAT TYPE
or souno TRACK Is USED ON THE PHoToPHoNE TYPE
FILM?
EXPLAIN How
THE sounn cAN BE REPRODUCED DIRECTLY FROM THE
sounn FILM
G'THE MovIEToNE SYSTEM ASRECORDING PROGRESSES?
How ARE THE
SOUND MODULATIONS RECORDED on THE FILM or THE
PHoToPHoNE
SYsTEH? -
CAN THE
sAHE MOTION PICTURE PROJECTOR aE USED FOR THE RE-
PRODUCTION
or SOUND AND scENE FROM EITHER A MovIEToNE on
