The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1925-08-28

The Schematie Wiring Diagram Of tn
Condensers Are
BY HERBERT e. HAYDEN, In New
York Herald Tribune.
A circuit of general usefulness is
the one shown In the diagram, for 1t
will operate fairly well even under
most unfavorable conditions and Is
safe In the hands OF the novice. Like
the neutrodyne, 1t has three controls,
and the set may be logged-that Is,
once the settings for given station
are determined they will always be the
same unless the aerial Is changed.
One Of the chief advantages of the
neutrodyne is 1t may be readily adapt
ed for family use. Anyone who knew
the combination" could hear the sta
tons Normally, this is not true Of
regenerative SETS There Is an ele-
ment OF great uncertainty Of setting in
sthe regeneration control dial. To over
come this, yet retain the advantages
of regeneration, this circuit was de-
vised. 1t Is a modification of Wea-
gant's \ circuit, the so-called divided
circuit, and embodies a stage of tuned
radio-frequency application, tuned
detector input, capacitatively coupled
regeneration in the detector Stage and
two steps Of transformer coupled
audio.
Preventing Radiation.
This circuit has as small a tendency
to radiate as any of the regenerative
hook-ups, and radiation may be effec-
lively prevented by connecting a mid
get condenser between the grid and
plate posts of the R. F. tube, the one
at extreme left. The setting Of this
condenser is varied until the signal Is
barely audible. or preferably inaudible
when the r. F. tube is barely lit. Then
the setting of this small condenser,
not shown, is left in that position.
The hook-up in performance Is as
good at "distance-getting."
condensers Used.
To facilitate tuning on the low
waves ii is well to use condensers that
are modified so as to cause the dial
readings to be wider apart for given
stations on higher frequencies. These
would be what are termed straight
line wave length, straight-line-- fire.
quency or like condensers. The usual
condenser varies as to capacity, which
tends to crowd the stations close to-
gether In dial position on the lower
divisions, due to the changes in ca
pacity at those points representing so
much greater frequency difference
The idea may be popularity expressed
by saying that an ounce of capacity
at the lower end makes ten times as
great a difference In frequency as
pound of capacity at the upper end
of the diaf
The condenser used in the set was
the Remler Twin Rotor, which, when
properly connected. eliminates body
capacity effects In tuning. The rotor
Of the condenser tuning the r. F.
stage should go to minus A, the stator
of the detector input tuning condenser
should go to grid condenser, and the
rotor Of the feedback condenser should
go to plus A.
CONSTITUTIONAL Data on Coils.
In choosing the coils for the set one
may be guided by his own particular
preference in design, or may follow
the directions for making the diamond
weave coils shown. These are wound
on forms having an odd-numbered
group of removable, radiating arms or
spokes. 3-16-inch dowel sticks, on a
circular hub, 2 inches in diameter.
Using No. % double silk-covered wire,
wind ten turns, halt, then pick up
twelve feet of the same kind of wire,
and wind this along with the remain
der of the other or secondary wind
ing. Leave four inches slack for con-
nections inside the set. Up to this
point you will have wound ten plus
about eleven. or about twenty one
turns of the secondary, and will have
completed the primary, the twelve-foot
length Now continue winding the
secondary until thirty more turns are
put on, whereupon this winding. too
is terminated. Thus you will have fin
ished coil with an eleven-turn pri-
mary and fifty-one-turn secondary
One more turn or less on the Sec
ondary will not matter. The sec
variable condenser