Experimental Crystal Set Receivers - Hints, Tips, and Secrets Submitted to the Publisher of Modern Electrics

52 Pages·2005·7.665 MB·English

by  Modern Electrics Magazine

Experilnental Crystal Set Receivers
An anthology of articles extracted from 1911
and 1912 issues of MODERN ELECTRIC~ MAGAZINE
repnnted by Lindsay Publications Inc

Experilnental Crystal Set Receivers
Hints, Tips 8 Secrets
submitted to the publisher of
Reprinted by
Originally published by Lindsay Publications Inc
Hugo Gernsback Bradley IL 60915
New York
Design© 2005
original articles appeared
in 1911 & 1912 issues of ISBN 1-55918-327-6
Modern Electrics Magazine
2 3 4 5
A GALENA DETECTOR COMBINATION GALENA DE liking; but I would suggest, for the up
Herewith is a photo of my detector. It TECTOR. rights, Yi inch square brass rod, each I
works well, and needs no descriptive matter This detector is used in case a quick inch high. The distance between Ar and
to work by.
The whole surface oi the Crystal "Galena" change is necessary. If one of the points A2 I~ inches, and 1 inch between A1
can be easily searched, by gently lifting t11e of this detector happens to be knocked and BL The springs between X and A I
spring with a match and letting it down again. out of adjustment by static or other will hold the mineral in tight adjustment,
means the other detector can be easily while the check nut in A2 holds the other
thrown in the circuit by making use of rod from slipping.
the two point switch. The arm of this Contributed by
switch b connected to one side of the cir JESSE SAUTER.
cuit while the points are connected to Bx
and B2. The base of this detector, or
Ax, A2, A3. are all connected together CONTACT FOR LOOSE COUPLER
and led to the other side of the circuit. While building a loose coupler of the style
You will find that this detector can be described in "How to Make Wireless Instru
ments," the idea of placing two springs on
my secondary to make contact with the rods
did not seem very good to me, so I bought
two brass curtain rods, J/16 inches diameter,
of the kind that has a small lube ,JicJing into
a slightly larger one. l used the small tubes
for the rods on which the secondary slides,
and after cutting two piece; of the larger tube
the lengt11 of my secondary, I soldered one
end of the wire wound on the secondary to
one large tube and the wire from chc switch
to the other tube. I then placed the tubes in
holes bored one inch above and 1,elow the
center of the end pieces of the secondary. I
find that it is possible to obtain a better con·
tact by this means than by the springs, be·
cause the whole weight of the secondary lies
upon the brass tubes, and I also find that the
secondary slides much easier this way.
adjusted to the highest degree of sensi Contributed by
T. E. JONES.
M odeni Electrics has a good circulation in tiveness, and is easy to construct, its di
this colony, and is very popular. mensions being m(\de according to your
Contributed by
2
W. F. HALL, Australia.
A TUNING COIL SLIDER. AN ADJUSTABLE CONDENSER. that this condenser cannot be used for
secondary purposes.
The rod is made of two No. 14 brass The condenser consists of 10,000 Contributed by J i\lVIES G. FITCHETT.
wires, D. square inches of tin foil and wax paper,
The slider is made of a brass block, made up in seven sections as per
B, three-eighths inch square and. one sketch; l'.I: pieces of brass, 1 inch by 1 HOW TO MAKE AN EXHAUS
-0 eighth l n ch inch by 3-16 inch, and 2 pieces ~ inch TED COHERER.
thick. Tw o by 3-16 inch by 7~ inches; 14 binding Procure tJ.IJ: inches of glass tubing
h o I e s arc posts; and 12 plugs to ~t holes as p~r such as is used in a chemical labora
drilled o n e - sketch. The condenser 1s made up m tory, about one-quarter of an inch i_n
sixteenth inch the regular way, first a sheet of wax pa diameter. Take a dime and cut from 1t
from the edge, per, then a sheet of tin foil, until sev~n two disks, B, about one-quarter of an
F, so that the condensers have been made. It will inch in diameter. Next get two inches
E wfiti rtehse whiolll esju. st pblea isne, etnh abty t htehree siks eptcrahc, tiwcahlilcyh nios lvimeriyt of copper or brass rod one-quarter of
The spring, to the different capacities that can be ..·1,-.- . Q.- ·~
C, is to 1~1ake obtained. This condenser can be used
contact w t t h for primary circuits or tuning, and is B
the tuning coil a very useful instrument around the
wire, and is laboratory for experimenting purpos_es. o~
fastened to the The tinfoil sheets can be cut any size A•01"1C
block, B, by to suit the maker. It is understood 0 BC·-SCOILP¥P£1i'1R PI.~
f means of the E· " "
~"8fltA.5~e.AP
battery bind 2·~1EClS~0JC~i< 7f H.• TtiS! 'l"l'tfr/P..\/(iW.
i n g post, G,
M. t.. and the hard J.4-B1NOIN<i an -iud1 in oiamcter and cut it into two
rubber knob, E. POSTS pieces each one inch long. Solder the
silver disks to one end of each of these
The brass wires are fastened to the
rods, E, neatly. Next get t"wo pieces of
tuning coil ends by means of brass
No. 22 platinum wire, each one and a
screws.
Contributed by half inches in length; drill a small hole
in the other end of the rods and solder
BERTHEL CARLSON.
the wire in these as in E.
The next is a delicate job. Both of
these plugs are filed to lit t·he tllhe
3
off the short piece and leave the tip. test tubes, with corks to fit; enough
Place the filings in the tube, made of tinfoil to cover both outer and inner
!14 per cenl. nickel and G per cent. sil sides of the tubes; two binding posts,
,·er. These can be obt?ined from coins, and four or five feet of green flexible
using a clean new file. Slip the other wire.
plug into position and pull the plati To begi11 construction, smaller spool
num wire through the tip, as shown at a is glued to bottom of larger spool b,
N. Space the plugs 011e-sixtcenth of an to form a stand. Then six %-i11ch
inch apart, and seal olT this tip as was holes FI arc bored straight through
the first. The tube is now filled with both butts. Cnre must be taken to get
mercury, using a funnel, tap the tube these holes spaced evenly apart.
so as to expel all the air bubbles. Fill The test lube~. after being covered
snugly and also must be airtight. Ex this tube completely and place your with the tinfoil by gluing, are slipped
treme care should be taken not to thumb on the end. Invert, and place into the holes in the stand forming the
break the tube, as it must be over forty the open end under the surface of the Leyden jars. The corks have a hole c
inches long. Next seal the plugs in the mercury, then release your thumb. bored through their middle, in which
tube. You will need a small bowl, Then with the aid oi a helper seal off
some mercury, and burner, also a help the tube above the mercun· level. as
er. Hold one end of the tube over the the mercury will drop to the thi~ty­
flame until it is red-hot as in L. Then inch leYe! as in P. Place. brass caps
seize with the fingers and draw it out over the sealed ends, making contact
to a point; break this off about one with the platinum wire. The instru
quarter of an inch from the long end ment is now ready for use.
and the end will look like J. Slip one Contributed by
plug through the open end and draw FANNON BEAUCHAMP.
the platinum wire through the small
end; hold this over the flame, and
LEYDEN JAR CONDENSER.
the glass will adhere to the platinum.
Measure about foar inches from the The materials needed for the con
sealed end and hold it in the flame: struction of this condenser are: two is inserted a wll'e S, connecting the
also hold another piece of tubing in the wire spools, one about six inches in inner covering of tinfoil to binding
flame at the same time; when both are diameter, the other tliree inches, the post d. Then wires are wrapped
hot touch the small pier:e to the long larger being four inches high, the tightly around the outside covering o[
piece at the four-inch mark and draw smaller Lhree inches in height; six the tubes w, connecting to binding
out a small tip, as shown at M. Brc~Ll< post e. 4
After varnishing, the device is ready found convenient to screw into the
for work. brass rod, if the outer coil is not suf
Contributed by ficiently flexible to allow the rod to go
JOHN B. BRADY. through both holes.
The condenser is built up of a num
ber of sheets of tinfoil and paraffined
A PORTABLE RECEIVING OUT
paper or some !iimilar dielecti-ic, as
FIT.
shown. The le;ids are made to a switch
"'
Below is described a portable wire
less outfit smaller than a small camera, than 4Y.lxiJ:~x3X inches. Black stain
SET C\..OSEO
in which sensitiveness is not sacrificed and a coat of varnish will give a fin
to saving of space. ished appearance.
It consists of a variometer, a conden Contributed by
ser contained within the inner coil, and LEWIS C. MUMFORD.
a detector of any type preferred by the
maker.
The ,·ariometer consists of a card ROTARY LOOSE COUPLER.
board cylinder, 1Ux30 inches in diam
eter, with the inner cylinder 3 inches fNER T\lat The [ollowing gives data for con-
outside diameter. Both cylinders are
wound with an equal amount o[ No.
24 B. & S. gauge enameled wire. In as shown in Fig. 2, after which the
placing the inner coil in position, a
whole conderiser is embedded in para
brass piece as shown in D'ig. 1 may be ffin. Two condensers would be an im
provement.
The mineral detector, either perikon
r.t:,, ~;;,;~:~""
or silicon, is used. The type sho>vn in
•"v"'•o•a< _.~-
. the drawing is very satisfactory.
F1Q 1. - The details of the construction of the
box containing the instruments are left
to the maker. The over-all dimensions
should be at the most a trifle more
struction of a loose coupler. The prim
ary is made of wood, and the secon
5 darv of hose.
C..o"'or/'13rr>
·~JG 2-
cut a groove on the circumference
about half an inch wide, and a quar
"""""""c;
ter inch deep, as per illustration. Then
I think the diagram explains all de with No. 24 enameled wire. The novel wind about a hundred turns of No. 36
tails. part is that each slider works in insulated copper wire on this disk,
Contributed by dependently, and that they are in leaving the ends for attaching to bind
WM. T. REBENHAULT. sulated from one another. It is con ing posts. Over this wind twenty
nected into the circuit the same as any turns of No. 22 copper wire in the
other double slide tuner. Drawing is same direction, having insulated it well
A ROTARY TUNING COIL.
self-explanatory. from Lhe No. 3f5 wire, also leaving
The following is a description of Contributed by leads for two binding posts. Then on
my double slide, rotary, and very ac- C. J. SEDLAK. positions indicated in diagram, screw
RuaaE'R TUNING TRANSFORMER
l'fN08
111'!81'£ WA(,Wfl't S As anybody knows who has tried it, TUNtN<; COil.
the making of a transformer for tun " 0
ing is a difficult job, and also a very
cl.umsy one. Another objection is the
expense oi material. A very efficient
substitute can be made as follows: Cut
., out a disk of wood one inch thick arid
about four inches in diameter. Then
curate tuner. The circle and base are
of 1 inch stock, the circle being wound
6
in bindit~g posts, connecting the ends After the pan is fastened to the base, HOW TO MAKE A SENSITIVE
of the wires, one to each binding post, two uprights arc provided, which are GALVANOMETER.
and mark them. Here we now have fastened to ~he base. about four inches
f'in<ling the need of a good galvan
a condcn~cd form of tuning trans irom the pan. Between the uprights,
ometer, and one that would be very
forme~, with_a _very short wave length. a metal rod is suspended, from which
;;ensiti,-c, witl1out paying a high price
A tuning coil 1s now connected in se wires are dropped down into each
ries with this instrument, and we have glass; and which is connected to the tor one, I succeeded in working out
Lile follo\\'ing-:
an arrangement which tunes sharper other binding posl. (See Fig. 2.)
and with much less trouble than the The glasses are now filled with a Make a base 4x4x% inches thick,
nf mahogany or walnut and bevel the
ordinary .tuning transformer, and cost solution of salt and water.
edges as shown in Fig. J. Make two
ing a great deal less, as almost every The capacity of this condenser is
standards or sides, 2;4x3.J4x.0 inches.
amateur possesses a tuning coil. The ,-aried according to the amount of so-
No. 22 wire is connected in the aerial
circuit, and the No. 36 in the receiver
circuit. I have found this to work as
good as a regular tuning transformer.
Contributed by
WALLACE ELLS.
ADJUSTABLE CONDENSER
FOR SENDING ONLY. 1"!1,.,-jA,,L.[
d:.•$~
First, select six or eight thin table
glasses, free from bubbles and cracks. lution i!1 the pan; or if a large capacity Fasten these to the base, with some
Lt is best to wax the tops of each glass JS required, the pan is filled with this good glue, 2,l!,I inches apart (inside
to prevent leakage. (See Fig. 1.) solution up to the top. If a low ca measurements).
Second, get a metal pan which will pacity is required, the solution in the Nol\' make a top of the same ma
hold all of ~he glasses, and which is pan may be but a few inches. Thus terial as the base, size 2;Y.lx2y.lx%
of the same !height as the glasses. the capacity of the condenser is va inches, and bevel the top edges of this.
The pan should be mounted on a ried according to the amount ol solu Drill a hole in the center, large enough
base, provided with two binding posts. tion in the pan. to admit a battery nut, see Fig. 2.
To one of the binding posts a wire is Contributed by Shape a piece of copper or brass as
fastened, which, in turn, is soldered to JAY JAKOWSKY. shown in Fig. 3. Make a cross piece to
the pa11. fit this, Fig. 3a. "Fasten the support
7
to the under side of the top, Fig. 4. mirror, ~x;h inches, and fasten in the other ends are brought on the outside.
This part of the apparatus works the slots (on the top of the cylinder), with to binding posts; sec Fig. 7.
same as t!he adjustinent of the E. I. glue. Fasten a small silk thread to the Now make a back and front from a
Co.'s electrolytic detector. Examine center of tq1e mirror with a drop of piece of plain glass and fasten the front
Fig. 4 carefully and all will be clear. glue, and the other end of the thread so that it will be removable. Fasten
\fake a thumb screw as described in must be fastened to the small hook on <1 dial on two pieces of wire so that it
November, 19ro, issue of Modern Elec the plunger, Fig. 7. The spring on the ll'ill be adjustable and finish instru
trics, page 452. The top may now be put bottom of Fig. 7 is made cf No. 10 ment with several coats of shellac.
in place with glue, and is shown copper wire which has been annealed, Fig. 7 shows a side view of the in
complete in Fig. 4. one end being fastened to the copper strument, and Fig. S shows a view
Next we must make a copper cylin q'linder and the other end to the base from the top.
der one inch long by one-half inch '~it:h a small tack. Contributed by
diameter. Prick or punch two small Now make two coils, each two inclhes
FRANK L. BUNKER
holes one-quarter of an inch from the long by one inch wide by three-quarters
of an inch thick. \iVind them in the
top, and diametrically opposite; also
two one-sixteenth of an inch from the form of an arc as described by Fig. 6. HOW TO MAKE A GALVAN
They should be wound on pasteboard
bottom. These are for the magnetic OSCOPE.
forms, and wound with fifty feet each
needles. Cut two slats in the top one of No. 36 wire. The resistance will A galvanoscopc for detecting $mall
eight'h of an inch deep and (wide then be approximately 100 ohms. They currents of electricity can be made
enough to receive a small mirror, size should be fastened to the sides of the from a coil of wi.re, A ; a glass tube,
Y<(x0 inch), diametrically opposite. box, witlh two pieces of wood as shown B, full of water; a core, C; and a
Magnetize two needles or small bits in Ga, and connected in series. The base, D; with binding posts as shown.
of steel about one to three-quarters of The core, C, which is made of iron and
an inch long. Place one of these in cork is a trifle lighter than the water
it displaces, and will therefore remain
the top holes of the copper cylinder
in the tube normally; but as soon as
with its north pole to the left. Now
a current of electricity passes through
place the other needle in the bottom
the coil, the core is drawn down out
holes, with the norfth pole to the right.
ui sig1ht. The current required is very
This is to prevent the earth's magnetic small as the core is so nearly balanced
field from affecting the readings, and that the lea!'t nttrnction will cause it
is called the astatic system. The to sink. The glnss tube may be a test
needles may now be fastened with a tube :is shown in Fig. 2. or any empty
drop of glue or shellac. Now cut a 8