The Challis messenger. (Challis, Idaho) 1912-current, 1925-07-22
These Diagrams Show
hitting and Receiving Of

For the actual operation of III
transmitter. the picture printed matte
or whatever Is to be sent, Is first photo
graphed on an ordinary camera film
This Is developed and then placed OF
glass cylinder being held firmly II
place by metal clips The picture l.
now ready to be transmitted.
inside this glass cylinder Is an In
candescent lamp, the light from which
Is focused In a minute beam onto the
film as the cylinder Is set IN motion
As the light and dark portions of the
picture are traversed by the light
beam, the Intensity of the ray is
changed. This ever changing beam
after having passed through the film,
Is again focused through another lens
outside the cylinder onto the sensitive
element OF photo-electrlc cell, a re-
cent development which transforms .he
light waves into electrical Impulses or
waves, which can be transmitted ny
radio much the same as regular datn
and dot message.
This photo electric cell Is commonly
spoken OF In the laboratory as the
eye OF the transmItter. The cleo
trical resistance Of this cell changes
In accordance with the amount of light
which falls upon 1t. and In this way
takes care of the shading of the picture
In transmission.
Tho Photo Electric Cell.
The photo-electric cell functions
without any lost motion.
That Is, the instant the slightest change
In the amount OF light reaches
the cell, corresponding change
In the output current of the cell takes
place. In this way the "eye" Of the
'ransmltter Is able to see" even the
iniest light variations. In fact the
eye sees and records electrically mil
Ions OF different current impulses as
he film sweeps by the light beam from
inside the cylinder.
The photo-electrlc cell Is. therefore,
esponsible for reproducing an infinite
lumber OF different electric current
alues which correspond with the light :
dark areas of the picture being
In order to cover all of the original :.
I'm, the glass cylinder Is rotated back =
nd forth and in this way the entire .
lrface Is eventually exposed TO the :.
eTclng light beam. The film rotates ~
rough an angle equal TO the width of :
o picture one notch at a time. Thus !,
lie upon line. the whole picture Is
yered
After the signal Impulses or electric d
ives from the photo-eectric cell pass
rough a series OF vacuum tube am.
Tiers, they are fed into modulatinp
Vice ready for transmission. The r.
ctrical Interpretation of the picture n,
then transmitted over land wires -,
m the London laboratory to the
rnavon (Wales) high.power trans r
ting station OF the Marconi Wire
Telegraph Company, Ltd. Here
electric impulses on the land wire
rate small relays which turn on and
the high value currents flowing
n the 20O-kilowatt generator to the
emma system. This higlrpower cleo =
al energy leaving the antenna In in d
upted Impulses. similar TO dots and L.
les Of the telegraph code, creates Ro,
ether waves which carry the photo
m through space 1900 miles to the
living station ON this side of the shell
ntic, located at Riverhead. Long be a
id. som,
No Special Circuits Needed. Fini'
lie development OF the photo-radlo- pam
transmltter has purposely been
ed on in connection with the es- Adj
shed radio transmitting stations.
engaged In sending radiograms
between Europe and America. On
ns ns" ue',ce uoes not require castiI
= "'"oon vi any special radio TENTH
io' e"cien' operation. lens
Riverhead. Long Island in rho Tho
Corporations central receiving into
N the operator tunes In to the nprno
won station He receives the pic avoidi
ust the same as he would a radio- limite
but instead Of dots and dashes with
nc ,"n ieau ne receives an I'M freQue
eI"o'e series OF impulses These freque
~ usn oank OF vacuum tube tances
e' n"u are 'hen seut by land as two
= 'ne laboratory Of the Radio able t
alton located in the building In on loo
street. the .,
inns unihteillgiDle code. carry are:
lhe pho'ograph, Is translated quenci
no o'acR and white, recording tuning
anal picture much In the style easy
ppieu engraving. small
ueFice III the hCA laboratory radiati'
~ operation involved between used.