Evening journal., 1922-04-25

phone headset The telephone re-
ceivers may be any OF the standard
commercial makes having a resist
ance OF between 1000 and 5000 ohms
The double telephone receivers
may cost more than all the other
parts OF the station combined. but 30
Is desirable to get them. especially
II Il Is planned 10 improve the re-
ceiving set later A single 1000-Ohm
telephone receiver with a head band
may be used but with less satisfac-
tory results.
Accessories.
Under the heading OF accessory
equipment may be listed binding
posts. switch arms switch contacts.
tcst-huzzer. dry battery. and boards
on which TO mount the complete APP
paratus.
The binding posts. switch arms
and switch contacts may be pur-
chased from dealers who handle such
goods or they may be readily impro-
vised at home The pieces OF wood
on which the equipment is mounted
may be obtained from a dry packing
box and covered with parafiin to
keep out moisture.
Care should be taken IN melting
The parsfiin not 20 get 90 too ho,.
For this reason q is a good plan to
melt il in a pan set In boiling water.
When the parafln just begins TO
smoke :. is al the proper tempera
iure.
When the wood parts have been
drilled and cut to size. the parafin
should be applied quickly with a
small brush. When cold. the ex-
cess parahin must be carefully scrap
cd off with a straight piece OF metal
such as the brass strip In the edge Of
a ruler
Construction.
Following is description OF the
method OF winding the tuning coil
and the construction OF the wood
panels:
TUNING COII-(See Figure a.
The cardboard tubing Is 4 inches IN
diameter by ~ inches long. one
end Of the tube should have tho
cardboard cover glued securely 10 II
About ounces OF No. "a Cor No
2e) double cotton-covered coppe
wire Is used for winding the coil.
Punch two holes in the tube abou
y inch from one end Weave tn
wire through these holes In such
way that the end OF the wire will D.
firmly anchored. leaving about /
inches Of the wire free for connect
ing.
Star. with the remainder OF thl
wire to wind the turns in a single
layer about the tube. tightly ana
closely together After 10 complete
turns have been wound on the tube
hold these turns tight and take OF
tap. This tap IS made by twistine
a 6-inch loop OF the wire together at
such a place that Il will be slightly
staggered from the hrst connection
This method OF taking of taps Is
shown clearly In Figure g.
Proceed in this manner until :
twisted taps have been taken of
one at every 10 turns. After these
first 70 turns have been wound on
tho tube. take of a 6-inch twisted
tap for every succeeding single turn
until 10 adullonal turns nave peen
wound on the tube. After winding
the last turn OF wire. anchor the end
by weaving IL through two holes
punched in the tube as at the start,
leaving about 10 inches OF wire free
for connecting.
It Is 10 he understood that each Of
The is taps is slightly staggered
from one just above. so that the taps
VIII not be punched along one line
on the cardboard tube.
IL might be advisable. after wind
Ing the tuning coil. 10 dip the turner
In hot parafin. This will helm &c
exclude moisture II Is important
10 have the parafin heated until Il
Just begins 10 smoke. as previousl,
explained 40 that when the turner