The Washington herald., 1922-07-23
ARMSTRONG HOLDS
INTEREST OF FANS
BY HIS INVENTION
Amateurs Meet With Lit
tie Success in Expert
menting With Device.
CURRENT AMPLIFIED
Noted Inventor Worked Six
Months Before Getting
Result from New Set.

Interest In the super-regenerative
circuit as successfully demonstrated
by Maj. E. H. Armstrong has not
waned. District experimenters re-
port some success. but none as yet
have produced the application of
$4,000 times normal signal strength
of which the set is capable. This
is not discouraging. for the in
ventor 1xperimented six months for
a single result
The new method can be used TO
receive any kind of radio signals.
telephony or telegraphy. 1t is par.
ticufarly advantageous for receiv-
ing short and continuous waves.
Experts declare super-resenera-
tion is an inventt' of tremendous
fmportace to radio.
Current Amplines Itself.
The new method is an extension
of the principle and the processes
of regeneration. By regeneration
the incoming current is made to
ampiify itself. The electro tube. a
bulb containing filament. grid and
plate may act as a detector and an
amplifier simultaneously. The cur
rent coming out of the detector
tube. instead of being connected to
a second tube. Is connected back
to the input of the detector tube
itself. The current is ampiified in
the tube and the process repeats it
self. These repetitions or feed
backs are made again and acaIn
but SO quickly that they are stimuli
taneous.
DR.. ]. H. Dellinger. chief of the
radio section of the Bureau of
Standards, who has conferred with
Maj. Armstrong on his method ex-
plains 1t as follows:
Regeneration has previously
been limited by the tube going into
the generating condition when the
feed-back was increased. Super
regeneration is a method of in
creasing the feed-back beyond the
point of self-generation without
self-generation actually taking
place. This Is accomplished by
taxing advantage of the fact that
self-generation does not take place
instantaneously. but time Is re-
quired for the generated current to
build up. With the feed-back great
enough to cause seif-generation the
current Is allowed to build up
for a certain interval and then the
amount of feed-back Is diminished.
thus stopping the building up of
the current. This process is re-
peated periodically. Armstrong ex-
plains the principle in terms of the
resistance in the tuned circuit. The
effect Of regeneration is equivalent
to introducing a negative resistance
in the circuit which neutralizes the
positive resistance to a greater or
less extent. Self-generation takes
place when the net resistance is
negative. Thus the process of
super-regeneration consists of
causing the effective resistance to
alternate between positive and neg
ative. This can be done either by
varying the voltage in the plate
circuit. which causes a variation Of
the negative resistance introduced
in the grid circuit, or by varying
the positive resistance of the grid
circuit, or by a combination of both.
Election tubes are used to produce
these variations An auxiliary tube
generating q frequency lower than
that of the radio frequency which
Is being received Is connected to the
tube which Is doing the amplifying.
One or the other of these tubes. or
else a separate tube is used as q
detector. A great variety of cir
cult Arrangements have been work.
ed out. All three functions can, in
fact. be combined In a single tube.
The adjustment and operation is.
however. complicated in this case.
Circuit Hard to Adjust.
Tn its present state the circuit
is little hard to adjust and
operate, but IL is expected that this
will be overcome by future perfec-
ton. Mai. Armstrong spent six
months enlarging the possible num-
Der of arrangements Of circuits for
his new method before he an
nounced his results.
The principles of the method will
be described in the proceedings Of
the Institute of Radio Engineers,
and practical data on operation will
be given in future issues OF QST.
the organ of the American Radio
Relay League. Apparatus embody-
ing Experimentation Is not yet
on the market commercially, and 1t
Is uncertain when the patent situa-
ito and commercial considerations
will permit II to be available for
purchase Maj. Armstrong has given
circuit details with great freedom.
In the apparent effort to assist in
dividuals to set up apparatus of
this kind for their own use,
Tt Is not only possible but de-
sirable to use a coil antenna when
super-regeneration is used. On ac-
count Of the large application
produced. an antenna Of the elevated
wire type would radiate strongly
when receiving signals. In order
to reduce re-radiation and prevent
interference between, nefghboring