The West Virginian. [volume] (Fairmont, W. Va.) 1914-1974, 1922-04-28

point but not so vide that e cans
not be set to touch only q single
contact. sS
The switch contacts may be Of
the regular type furnished for this
purpose or they may be 6-32 brass
bolts with one nut and one washer
each. They may even be brass
nails driven through the panel
with their individual tap fastened
under the head or soldered to the
protection Of the nail through the
panel.
The base is of wood approx.
mately z inch thick, 51S inches
wide and -101s inches long.
The telephone. binding posts
should preferably be OF the set
screw type.
Wiring
After the several parts men.
toned have been constructed and
with the exception OF the tuning
coill mounted on the wood base,
the wires may be connected to the
switch arms and binding posts and
the taps may be connected to the
switch contacts.
Awire is connected to the back
OF the lett-hand switch-arm bolt.
twisted into a spiral Of one or two
turns, like clock spring, and
then led to the back Of the binding
post marked ground" Connec-
ton is made to the binding post by
removing the insulation from the
wire and clamping between the
nut and washer.
The same wire Is now passed
through small hole and run un-
derneath the base TO the left-hand
binding post marked "phone." A
wirejis then run from underneath
the right-hand binding post mark
ed "phone" to underneath the
binding post which is part Of the
crystal detector. The cooper wire,
which was wrapped tightly about
the three brass wood screws that
hold the crystal in place, is led
underneath the base, up through a
small hole, and is then connected
to the back Of the binding post
marked "antenna." Another wire
is connected to the back Of the
rlght-hand switch arm bolt, twist
ed into a spiral of one or two
turns like a clock-spring and then
connected to the back of the
antenna binding post.
Wrap one end Of piece OF No.
"a bare copper wire tightly around
a nail, near the head, insert the
nail in the crystal detector binding
post, and adjust the wire until II
rests on the crystal as shown. The
detector is completed by pushing a
cork or wood knob on the pointed
end Of the nail.
The taps leading from the tuner
should now be connected to the
switch contacts. Scrape the cotton
insulation from the loop. ends Of
the sixteen twisted taps as we'll as
from the ends OF the two single
wire taps coming from the first
and last turns. Fasten the bare
ends OF. these wires to the proper
switch contacts as shown by tae
corresponding numbers in Figure
Be careful not to cut or break
any Of the looped taps. The con-
Meeting wires may be fastened to
the switch contacts by binding
them between the washer and
the nut. After all the wires from
the tuner have bean connected, the
tuner. should be fastened to the
base by two or three small screws
passing through the cardboard end
The screws should ba provided
with washers.
Operation
After ell the parts OF this crystal
detector radio receiving set have
been constructed and assembled
the first essential operation is to
adjust the fine wire which rests
on the crystal to a sensitive point
This may be accomplished in sew
erai ways; one method is TO use a
buzzer transmltter.
Assuming that the most sensl.
tive point on the crystal has been
found by the method described IN
the paragraph "The Test Buzzer.
the est OF the operation Is to 40.
the rest Of the operation Is to ad-
sonance or in tune with the sta
ton from which the messages are
sent. Fa~ :
The tuning Of the receiving set Is
accomplished by adjusting the In
ductance Of the tuner. That is. one
or both Of the switch arms are ro-
tated until the proper number Of
turns OF wire Of the tuner are made
a part OF the metallic circuit be
tween the antenna and ground, 60
that together with the capacity Of
the antenna the receiving circuit
Is In resonance with the particular
transmitting station.
1t will be remembered that there
a.ea10 turns OF wire between &C
tacent contacts OF the S-point
switch and only 1 turn Of wire be-
tween adjacent contacts Of the 10
point switch. The tuning OF tho re-
ceiving set Is best accomplished
by settling the right hane switch
arm on contact ~ and rotating
the left hand switch arm over its
contacts, II the desired signals are
not heard, move the right hand
switch arm to contact (g an ~
arm throughout its range. Proceed
In this manner until tho desirad
signals are heard.
It will be advantageous 70 know
the wave lengths used by the
radio transmitting stations In the
immediate vicinity, "A greater wave
length requires more turns Of The
rniT -. .-fr l7.