Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1922-05-12
Let's Mount Those
SDider,ceb Coils

upader. web or basket. woven coils made
and tapped, both tens and units. by rnis
ume. That is TO say, everybody has to
zap them by tens and all must tap
mem by units unless they are the prond
poSSessors of variable condcnSerS. \
variable condenser will accomplish the
same result as tapping by single turns
Of the coil, but it won't work up TO
such big values as are included in the
tens switch. An ordinary forty .threc-
plate condenser will give You about the
same range of wave length variation
~ twenty turns Of "a coil made on an
oatmeal box or one of these spider webs
That's apprOximatr.
We have already printed the form
Tor you to Use in cutting out the paste.
board wheel around which y"u wound
your spider web coils. You'll notice
that one of the spokrs was extended
beyond the circle and was squared of
at the end.
After you ave wound aud tapped
your coils yt place these two squared
ends together and glue them with a
hinge made Of insulating tape or good
tough dress braid. 80 that tne two coils
will open and close like the covers Vf
II book.
The illustration shows different
method. if you prefer Il. Each coil is
mounted on square Of board or heavy
cardboard by screw through the
center and the tNo boards are hinged
at one edge. This method probably
makes It more certain that the up-
paratus will keep is shape and the
coils will continue to close center 20
center instead of working l"p- sided.
However, use rith'r Incthod You wish.
The unit illustrated takes the piucc
OF loose coupler or Il yar!o- coupler or
a pair of honeycomb or duo lateral
coils in any "hook up you may See
In one Of the radio magazines.
1t is simply one board screwed up
right against the edge OF h"al or
board which is used FOR the base. The
upright board iS known as the panel.
We call the ''primarv' and the other
the secondary l. doesn't matter
which you make which. I have made
II a practice to use the bottom one As
the primary always. That saves con-
fusion when you make as many Of these
outfits as / do for experimental pur-
poses.
The panel illustrated Is the kind that
would be made by fellow who is the
proud possessor of two variable con-
densers. It has no units switches on IT,
The primary coil is tapped in tens only
and SO Is the secondary. If you haven't
the condensers you'll have 'c LAY out
your panel 50 as to include four
switches and four semi~ircleS of con-
tact points. two each for the primary
and secondary, one semi circle of each
for unit taps and the other for tens
taps.
II you have one variable condeu>er
you can use it either in the primary or
secondary coil circuits and thus climi-
nate the units taps for that coil. 1t is
best to use q single condcnS.r IN the
primary circuit. To do th!., instead
Of leading wire from the post marked
ground direct TO the cold water
spigot, you join that post and on" post
Of the condenser by wire and then Join
the other post Of the condrn>"r 20 IN"
wire leading TO the spigot. hats
what we call being in series. /,
means that all Of the electric forces
through the condenser before they reach
te spigot and thus 70 the ground.
If you prefer 10 use the Conler SEP
differently. You wire one post OF the
condenser 10 one post marked "-"c-
Ondary' Oh the panel, and the otNCr
post of the condenser TO the other sec.
ondary post. That's what We call
''parallel" or "shunt.'
The series Joining will shorten your
wave length in your primary circuit.
The parallel joining will lenstnen the
wave length Of your secondary coil.
The only part of this panel that re-
quires further explanation Is the knob
and thread and the scale marked along
side the thread.
Any kind of knob VII. do. boy
little wooden knobs intended for IN
pot lids in Il hardware store. IAey COST
one cent each. Fasten the knob TO lie
panel by bolt and nut and glue cnc
end OF the thread 70 it Pass the thread
up through two small screw eyes as
shown and down behind the pane 10
the upper coil and fas:en either by tying
around the screw or 10 the far edge ot
the coil OF the board. Il you have
mounted the coils this way.
When you turn the knob you W,nI
the thread up on Il and this Winding
lifts the upper coil away tron. rhe
lower az far a. you want 10 liz il. It's
separating Of the coils or letting them
fall together Is Whut We ca, varying
tho coupling. The coupling is tholr
hearness to each other.
There is knot in the thread and
when / use this outfit vary tie
coupling until ! hear signal at It's
best and make a note of the "coppiHg'
as indicated Oh the scale. Any kind Of
scale will do. II is merely to record
the coupling so that if you listen for the
same station the next night or the next
week you know where you found him
before and you are likely 10 find him
somewhere around the same adjustment
again.
Copyright, IscR. by Public Ledger Company