Evening star. [volume] (Washington, D.C.) 1854-1972, 1926-07-18
J. 7s: Learning by Experimenting,

No. 70: Learning by Experimenting
One Of the factors that keep Smith
eternaIly Interested in radio IS ms
habit of experimenting. He does not
think for q moment that the ideas ne
gets have not been thought OF by the
great minds that have given us the
electrical marvels of the day, nor
does he care il others think ne IS ex-
perimenting with things that already
have been tdiscovered." Smith has
his own discoveries to make II ne
ever is to- grasp the significance OF
this great new science and enter
tainment.
This explains why he has been ex.
perirnenting with his radio set in com.
bination with his photograph. He had
noticed the development OF the cleo
trio photograph and had been Won
dering what 1t is all about. Going to
music store he found that records
are being played electrically as well
as mechanically. In the new instru-
nlent a needle picks UP vibrations
from the records In the usual way,
but beyond that 1t AN is different.
Smith stepped around to the rear OF
the machine and noticed several power
tubes and transformer or two. The
music was coming from regular
cone loud speaker, although 1t was
concealed in such q way as to appear
like a regular monograph horn.
An hour after inspecting the new
instrument Smith was home playing
over hts records and trying to get the
final output through the ear phones
instead OF the monograph horn.
Experiment Unsuccessful.
The experiment was fruitless upon
the first attempt, but like all. true in
vestigators and pioneers he made I'M
mediate plans for a second attempt,
casting all thoughts Of failure aside.
Smith knew that by holding a nee.
die, pin or any other sharp pointed
device to the grooves of a phono.
graph record and allowing the latter
to revolve at about so revolutions a
minute sounds would be reproduced
identical with those impressed upon
the record. The comparatively sim-
pie photograph reproducer then am.
plifies and gives the reproduced
sounds or vibrations their proper
values To certain extent this Is q
matter Of utilizing the principle OF the
lever, as any one will note by exam.
lining q reproducer. A metal or mica
diaphragm gives the vibrations to the
air as does a telephone, only in the
latter it Is the variations in the cleo.
trical current passing through the
tiny electro magnet that does the
work.
From this Smith concluded that It
would be necessary to substitute a
telephone reproducer instead Of an
acoustic type If anything was to be
done along lines of electrical repro
duction of records. He remembered
that the reproducers of the electric
monographs were magnet shaped.
So Smith tried to convert one OF
the ear phones into q magnetic re-
producer. using q special metal Ola
phragm which he had taken from q
photograph reproducer. This had the
needle holder and lever already at
tached. Suddenly, however. he real
lied that he was building sort OF
microphone, and the realization that
ii would be necessary to pass a cur
rent through such a device impressed
him as being little too much for his
rather limited skill in this line.
Still, he was learning. Learning by
experimenting. 1t gave him new
picture of the nicrophone. He could
see that when sound vibrations are
impressed upon q diaphragm through
which q current is passing, that cur
rent is modified. This current can be
made to modify an immensely strong
er current, as is the case in radio
transmission.
! Picking Up Vibrations.
In a regular microphone, or q tele-
phone receiver, vibrations are carried
by air waves. In the electric phono-
graph they are carried by the needle.
which also serves to pick up the vi
brations at the correct rate from the
record.
Nov" said Smith, as he complet-
ed his mental picture of the process
of picking up the vibrations. If !
could just feed the output of the
electrical reproducer to the aerial
post of the radio set I should have
enough music to entertain the neigh
borhood."
But he was dead wrong. II he had
tried 1t he would have found nothing
but failure, because the electrical fire.
quencies carried by such a reproducer
and its special microphone circuit
would be at audio frequency. In other
words, the current flowing to the
tubes of the electric phonograph is