Evening star., 1922-05-30
USES STAMP SOCKET
AS RADIO BATTERY
Bureau of Standards De.
veIops Unusual Receiv-
ing Set.

The bureau Of standards of the
Department Of Commerce has de-
veloped in an experimental way a
radio receiving set in which the usual
batteries are eliminated, and con-
nection is made instead to the Or
dinary electric lamp socket The ap-
paratus is an amplifier. which con-
stitutes a receiving set when used
with a simple tuner. 1t may be used
with any type of antenna, ie., with
the ordinary elevated wire antenna, a
coil antenna or special forms of an
tenna.
The storage battery ordinarily re-
quired to light the filaments of the
electron tubes is a drawback to the
general use of radio sets. The bat
terry must be charged from time to
time. it is bulky and heavy. and the
damage in a household. In this am
plifler both the filament storage bat
terry and the dry battery used in the
plate circuit are replaced by spe-
cial transformer and an electron- be
rectif1er an accessories, the aggre-
gate bulk and weight Of which is
less than that Of the batteries.
Small Dry Battery.
1t uses a small ten-volt dry bat
quired to deliver only a small cur
rent and should have a life prac-
tically equal to the life of the bat
terry IL not used at all, f.e., at least
several months. In order to reduce
the hum of the alternating current,
there are more adjustments to make
than in the ordinary amplifler sup
piled from batteries.
OF the parts which in this amplif1er
replace the storage battery in the
ordinary amplifier, the special trans
former is the only one. the cost of
storage battery. The cost of the
transformer would probably be main
ly the labor Of assembling. A state
fnent was made in an early announce
ment of this amplifier that the
storage battery is the most expen-
receiving set This may have been
somewhat misleading, as the aggre-
gate cost Of the electron tubes in
amplifers which employ several tubes
may exceed the cost of the battery.
The cost Of the battery, however.
sary battery charging apparatus, gen.
orally exceeds any other item, even
in an elaborate amplifier.
A few details of the amplifier
which utilizes sixty-cycle current
supply for both the flaments and
plates OF the lectron tubes are as
follows: This amplifier has three
radio-frequency stages and two audio-
frequency stages and uses a crystal
detector. The sixty-cycIe current
when used in an ordinary amplifier
circuit introduces a strong sixty
cycle note in the telephone receivers
and makes reception impossible. This
has been practically eliminated by
the balancing resistances, grid con-
densers and special grid leaks of
comparatively low resistance, tele-
phone transformer in the output cir
cult, and use of crystal detector in
stead Of electron tube detector. In
the Anal form of the ampiifler there
Is only q slight residual hum which
is not Objectionable.
The amplifcation obtained with &C
supply was as good as that obtained
with the same amplifier used with
dc supply. The complete outfit is COM
pact and portable. The amplif1er as
constructed operated most satisfactorily
for wave lengths from 200 to $50
meters. This range was determined
by the working range of the radio
frequency transformers used. BY
using suitable radio frequency trans
formers this range can be extended
to receive any radio waves.