Scientific Explorer Crystal Radio User manual

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You will also need the following things:
- pencil
- 4 thick books
- scissors or wire cutters
- magnifuing glass
- small screwdriver
WARNING:
This radio works without any electrical source. It must not be
connected to any electrical appliances or to an electric outlet.
Beware ofsharp points and rough edges.
rubber fiands

BTIILDING THE RADIO
Getting Started
A. Listen to the Earphone
BgF* putting the crystal radio together, you should examine two
of its parts, the earphone andthe ttiode.
lhe _earplone is one of the most important parts of your crystal ra_
dio. It is the earphone that changes itectricil impulses into"sound.
Any small electrical impulse will make the earphone click.
Many common things contain a tiny electric charge.
lut tle.earphone to your ear. Hold one bare wire end in your hand.
louch the other bare wir_e end to things around the hous6: a water
faucet, a metal window frame, or a ridiator.
WARNING:
Do not touch the wire to a wall socket, or to a lamp outlet, or
to anything that carries electricity.
B. The Crystal Diode
The heart gf your crystal radio, the part that contains the crystal, is
the diode. Be very-carefu! when you open the package that"con-
tFms your crystal diode! Diodes are made of glass and can break.
A diode is an electrical device that lets current pass only one way.
The reason that this is important is a complicatld or.. io, *itt
learn more about it later, in the section "ail"d "How Radio works,,.
Jf you have a magniffing glass, take a close look at the diode with
it. Inside the glass qbe-ia a tiny speck, a crystal of germanir-, or.
of the rarest metals in the world. Pressing against ifis ve.y hn"
wire. Can you see the crystal and the wirif (See Fig. 1)- '

Building the Radio
A. Prepare the Tirning Coil
1. The flrst step
coil. Start with
end of the wire.
2. Slide a rubber band over
one end ofyour coil tube.
Slide it down about ll2 in.
from the end of the tube.
(Fig.2)
B. Wind the Coil
in building the crystal radio is winding the tuning
the spool of wire. Take the tape offit, and find the
Fig.2
coil tube
Note: Adult help is advisablefor this task. Winding
the coil must be done very carefully and precisely, or yoar
radio will not work. Fig" J
1. Slip the spool of wire onto a
pencil. Rest the two ends of the
pencil on two thick books. Then
put two more books on top of
the pencils to hold them in place.
The spool can now turn freely on
the pencil. (Fig. 3)
2. Hold the end of the coil tube loosely in one hand, with your
thumb over the coil wire.
Now turn the coil tube with vour
other hand. Keep your thumb resting ttg' 4
on top of the wire, guiding the wire so
that it lies smooth and flat on the coil
tube. The wire must be wound so that it
is only one layer thick, with the wires
lying snugly side by side. The wires
should touch, but they should never
cross or overlap one another. (Fig. 4)
3. When you come to the end of the wire, finish up so that the wire
at the beginning of the coil and the wire at the end of the coil are on
the same side of the
F--/ rubberband

Fig.5
coil tube. Be sure you
have at least 3 inches
sticking out over the end
of the tube. (Fig. 5)
4. Slip another rubber
band over the tube and
wire to hold the end of
the wire in place. Make
sure your coils are neat and tight, and put the tuning coil aside.
C. Prepare the Base and Insert the CoiI
1. Place the plastic base face down, so that you don't see the printed let-
ters and words. Bend up the square back panel and bend in the two tabs.
2. Now bend up the two side panels. If there are circles of plastic in the
side panels, just push them out and throw them away.
3. Bend in the tabs on the side panels. Push them into the slits in the tabs
of the back panel. Make sure that the tabs lock securely in place. Don't
bend the front panel up yet.
4. Slip one end of the coil into one side of the base. Slip the other end
into the other side of the base.
5. Turn the coil so that the ends of the coil
wire are next to Hole D on one side of the
base and Hole B on the other. (Fig. 6)
Slip one wire through Hole B. Wind this
end around and through Hote B twice and
cut it off.
6. Slip the other wire through Hole D on the other side of the base. But
DON'T cut it off.
7. Your coil wire is covered with a film of thin, clear plastic insulating
material. Electricity cannot get through it. You have to clean this film off
the end of the coil wire that goes through HoIe D. Here's how:
A. Fold your piece of sandpaper, sand side in.
B. Put about 1 inch of the end of the coil
wire in Hole D into the folded sandpaper.
C. Squeeze the sandpaper and pull the end of the wire out
of the fold. Do this at least 10 times. Keep turning the wire.
Sand off the insulation all the way around. Save your
sandpper. You're going to use it again later.
__-_--/ rubber bands
7 ...--3 in. [?.s cm]
Fig. ri

D. Prepare the Earphone, the Diode, and the Connecting Wires
1. Unwind the 2 wires that are twisted together on your earphone, so
that each wire end is approximately 6 in. long. Tie a simple knot in
the wire so that the wire does not unwind any more. tsig.7
2. Make a small loop at the end of each diode
wire by bending the wire around the lead of a
pencil. (Fig. 7) The loops should be able to slip
over the end of one of the bolts supplied with
your kit.
3. Make a smallloop at one end of each connecting wire, the same
way you did with the diode.
E. Put the Earphone and lirning Rod onto the Base
1. Put one earphone wire into Hole D and out again through
Hole C.
2.Do the same with the other earphone wire on the other side of the
base. Put it in Hole B and out HoleA.
3. Make a smallloop at the end of each earphone wire around the
lead of a pencil.
4. Push the tuning rod into Hole 1. Push the rod in a little way and
slip the tuning ball onto it. Then push the rod all the way through
until the rod goes through Hole 2.
5. Turn the tuning rod so that the eye lines up with Hole 4. Your
radio should look like the drawings in Fig.8a & b.
Fig.8o
I*ft side Fig" sb Right side

F. Make Connections
Now you arcready to make connections.
1. Put the end of one connecting wire without the loop in through
Hole D and out again through Hole C.
2.Prepare a bolt by slipping a washer onto it. Then slip the loops of
the following wires onto the bolt:
-the connecting wire
-the nearest earphone wire
-the coil wire
3. Slip on the second washer, and put the bolt into Hole 5.
All this stuff can get confusing. Work slowly and carefully.
You'll get it right!
4. Hold the bolt tightly against the base. With your other hand,
put a nut onto the bolt and screw it on loosely. This is the ground
("earth") connection Check to make sure that all wires are clamped
between the two washers.
5. Thread the second connecting wire in through HoIe B and out
again through llole A. Slip a washer on another bolt. Then slip on
the loops of:
- the other connecting wire
-a diode wire
6. Slip on the second washer and put the bolt through the eye of the
tuqing rod and into Hole 4. Put on a nut and screw it on loosel)z as
before. This is your antenna connection.
7. Put a washer on another bolt, and slip on the loops of:
-the diode wire
-the remaining earphone wire
Put on a second washer. Push the bolt into Hole 3, and screw on the
nut.
r

8. Now tighten all your connections by screwing on the nuts
tightly as possible. Your drawings should look like the ones
Fig 9a & b.
Fig. $a
I*ft side Fig. sb
fright side
llole 5: a connecting wire
an earphone wire
Ilole 1: the tuning rod
Ilole 3: a diode wire
an earphone wire
Hole 4: the eye of the tuning rod
a connecting wire
a diode wire
G. CheckYour Connections and Close Up the Base
1. Check your connections:
Left Side:
Right Side:
llole 2: the straight end of the tuning rod
Remember, all connections have to be made correctly on bare
and securely tightened or the radio will not work.
2. Close the base. Fold the front panel towards the coil and slide the
tabs on each side into the slots near Holes D and B.
H. Sand the Tuning Coil
The tuning ball must make contact with bare wire on the tuning coil.
But your coil wire is still covered with a clear plastic coating. The
entire length of the coil under the rod must have the insulation sanded
off. Here's how to do it:
1. Run the tuning ball back and forth a couple of times so it makes
a light mark along the top of the coil. Then turn the coil tube just a
little so that the mark moves out from under the rod.
earphone urire
earphone wire
;:::;t,*
":,'2tr:l:i*

2. Sand gently along the mark until the insulation there is removed.
Then roll the tube back so that the sanded area is under the tuning rod
again.
Remember, if the ball doesn't make contact with bare wire, your
radio won't work.
Your crystal radio is now ready!
I. Listen to the Radio
Take your radio to a cold water faucet. Touch the faucet with a con-
necting wire, and hold the bare end of the other wire in your hand.
(To make it easier, attach the bare part of the f,rst wire to the tap with
a rubber band).
Now put the earphone in your ear. Start moving the tuning ball
slowly until you pick up one or more stations.
The sound will not be loud. A crystal radio does not have the power
that a regular radio has. It lacks an amplifier. But if the reception in
your area is good, you should be able to pick up more than one sta-
tion.
EXPERIMENTS WITH YOUR RADIO
1. Experimenting with Different Antennas
A crystal radio works well only if you have a good antenna (aerial)
to receive the radio waves. The farther you live from a radio station,
the better the antenna must be. A cold water tap makes a good an-
tenna. This is why you attached one of the wires to the water faucet.
You used the faucet as an antenna.
Now try other things. Take the wires offthe faucet. Touch the wire
to different items: a drainpipe, a door, a wall, awater pipe, a metal
window frame, andawooden table. DO NOT TOUCH ELECTRI-
CAL WALL OUTLETS OR LAMP SOCKETS. DO NOT TOUCH
ANYTHING THAT CARRIES ELECTRICITY
Outside you might try metal railings, a tree, a car antenna, a concrete
wall, metal flagpoles. Remember: make sure that when you touch
something with the wire, you hold the other wire in your hand.
Listen each time. Which items make good antennas?
-Try other things around the house. What material gives you
the best results? Wood? Plastic? Glass? Metal?
- What size antenna gives you best results: something big,
something long or something small?

2. Experimenting with Different Grounds
You can improve the reception of your crystal radio even more by
connecting it to a ground (earth)-any piece of metal that leads to the
earth. The ground (earth) for a crystal radio acts just like another
antenna (aerial). A water pipe or a radiator will make a good ground.
As before, remember to hold the bare end of the other wire in your
hand.
Try combining different antennas and grounds. Do you get differ-
ent stations? Try switching the antenna and the ground wires to see
which brings in the louder sound.
3. Identifying Stations
By now you should have tried several different combinations of
antennas (aerials) and grounds (earths). Now choose a good location,
and try to identiff the different stations you can pick up. There are
two ways to do this:
l. Listen until the station announcer identifies the station.
2.Try to get the same station on a regular portable radio.
4. Identifying Stations Using Different Antennas
Try identifying different stations by connecting your radio to differ-
ent antenna combinations. Do you pick up the same stations that you
did before? Are all stations you pick up ones that you can identi$z?
Crystal radios are peculiar devices. Sometimes you may pick up very
distant stations, even broadcasts from another country!
5. Keeping a Record of Stations
You may want to keep a record-called a log-of the different stations
that you hear. In your log you should note the date, the time of day,
the call letters of the station, and the city where the station is located.
You might also want to note what combination of antenna (aerial)
and ground (earth) you were using, and the approximate position of
the tuning ball on the turning coil. Use the scale on the base for easy
identification.
6. Trying the Radio at Night
Listen to your crystal radio several hours after dark. You may find
that you receive different stations, especially ones that are far away.
HOW RADIO WORI(S
By now, you may be interested in knowing something about how
your radio works. Let's start by taking a look at the radio station
where the whole process starts.

Meanwhile, at the station's transmitter, an electrical device called an
oscillator is producing another electric current. This current is AC-
alternating cqrrent. An alternating current is a current that continually
changes the direction of its flow in an electrical circuit. First it flows-
in one direction, then it reverses and flows in the opposite direction,
then it reverses again, back and forth, many times aiecond. The AC
produced by the oscillator alternates this way
about a million times a second. An l'ig" 11"
In the sound studio of a radio station,
a radio announcer is speaking into a
microphone. Fig 10a is a simplified
diagram of the announcer's speech. The
peaks and valleys of the wavy line rep-
resent the loud and soft sounds of what
is said.
The microphone takes these sounds
and turns them into electrical impulses
that exactly correspond to the pattern
of the announcer's speech, illustrated
by Fig.lhb. Loud sounds make for
strong electrical impulses. Soft sounds
make weaker impulses. A diagram of
the strengths of the electrical impulses
would match up with the sound diagram
exactly.
$
Fig. lob
electronics engineer would say it --.cunrent gring
has afrequenZy of abor* a miilion lr,l,lfiflj| &A" one *$.av
cycles.or a million Hertz. (Amillion TITTWTTI-_ current goins
HertzisalsocalledoneMegaHertz). rt'r' r I I I stherrvay
Fig.ll is one way of illustrating this
a-lternating_ oscillator current. pattern of the announcer's speech,
illustrated by Fig.lhb. Loud sbunds make for strong electrical .
impulses. Soft sounds make weaker impulses. A diagram of the
strengths of the electrical impulses would match up wittr the sound
{iagra-m exactly._At the station transmitter, the eleitrical impulses
fiom the microphone are combined with the current from the oscil-
lator. The result can be illustrated in Fig. 12.
currenl going
-nnf .neway
-'-'"-=-. triurrant going
other way
Fig, TAa
,rr. ,,
1
+ffilttffi1=
10

Notice that the bottom half of the new current is a mirror image of
the top half. In the top half of the diagram, the current is flowing
one way; in the bottom half, it is flowing the other way.
Ahigh-frequency current, that is, a current that alternates very rap-
idly, has a peculiar property: it gives offradio waves which have the
same frequency as the current that produced them. Radio waves are
somewhat like light: they spread through space at a speed of almost
200 thousand miles per second without needing any wires to carry
them. Unlike light, however, radio waves are invisible, and they can
travel through objects that would stop light-objects like trees, or
buildings, or people.
When the radio waves strike a long piece of
wire, like the crystal radio antenna, they cause
an electric current. This current is a very
weak copy of the transmitter current thit sent
out the radio waves back at the station (see
Fis.13)
The alternating current set up in the crystal
radio antenna travels to the diode. The diode
is a one-way electrical switch. That is, it lets
through electric current moving in one direc-
tion but blocks any current moving in the op-
posite direction. In effect, only the "top half'
of the AC current gets through.
Fig,7a
Fig.1,5
From the diode, the modified current goes to ^ A
iiTir,[:1"#"'l;]#H#J :Llffi :ffilil3J' .,/ " h^. 16r
in the announcer's speech. impulses in the -g
announcer's speech. We hear the announcer at
almost the same time she/he is speaking.
MORE ABOUT YOUR RADIO
The Circuit Diagram of the Radio
When you built your crystal radio, you made a number of moderately
complicated mechanical connections. Several times, you passed two or
three wires through different holes in the base and twisted them around
various bolts. You probably gave very little thought to what the final
connections look like as a whole.
ll

But if you look at the top of your
crystal radio and trace out the
pathway of the metal wires and
connections, you will find that it
looks something like Fig. 16.
An electronics engineer would
want a clearer diagram than this.
The engineer would use the sym-
bols shown inFig. 17.
Using these symbols, he or she
would produce a diagram that
shows in the simplest way the
pathways, or circuit, that elec-
tricty can take in the radio. This
kind of diagr&m, shown on Fig.
18, is therefore called a circuii
diagram.
Compare this circuit diagram
with the earlier sketch of the
radio. Notice how much simpler
the circuit diagram is. But notice
how the circuit diagram shows
the same essential information as
the drawing.
- First, there is a pathway for
electricty from the coil.
-Then there is an antenna (aerial)
connected to the circuit
between the tuning ball and the
diode. -And there is a ground (earth)
wire connected between the
coil and the earphone.
F-
tuningball
@
earphone
C]
diode
Fig.17
Y
antenna
='L
,*E
ground
rig' t8
- First, there is a pathway for electricty from the coil.
-Then there is an antenna (aerial) connected to the circuit
between the tuning ball and the diode.
-And there is a ground (earth) wire connected between the
coil and the earphone.
the CrysJaI Radio Compared to a Regular Radio
You may be interested in the similaritieJand differences between your
crystal radio and a regular radio.
Fig.16
t2

A regular radio has a power source-batteries or an electrical wall
socket. It also has transistors in place of a single diode. The outside
electrical power and the transistors work togeTh er to amiiiyy (fik;
stronger) the electrical impulses caused whdn radio wavler"jt ike the
set's antenna.
This amplification permits a regular radio to pick up more stations
wrth a much smaller antenna. The extra power also^runs a loudspeaker
instead of an earphone.
Another difference is the tuner of a regular radio, which allows FM
broadcasts. FM is clearer, butAM sigials travel iarther. iour crystal
radio picks up onlyAM
g-asic_{!V, your crystal radio and a regular radio work alike.
The difference between the two mak6 the regular radio more efficient.
I
I
13

CE QU'ILYA DAIIS TON KIT
=1 -1 1
eoil fiibe
eatphone
sond paper
Tu auras besoin aussi des choses suivantes :
- crayon
- 4livres 6pais
- des ciseaux ou des coupe-fils
- une loupe
- un petit tournevis
AVERTISSEMENT:
Ce rdcepteur fonctionne sans 6lectricit6. Ne pas la brancher it
un appareil 6lectrique ou d une prise dlechique. prendre garde
aux coins pointus et aux bordures rugueuses.
r
re
funingrod
t4ll
rg
firning baII
&
diade
@
2 connecting
wires
€nrcdterr
ffru
bolts,
@ffi
rubber bands
t4

MONTER LE RECEPTEUR
Comment d6marrer
A. V6rifier I'6couteur
Avant d'assembler le r6cepteur i cristal, examinez deux de ses
pidces : 1'6couteur et la diode.
L'6couteur est l'une des parties les plus importantes de votre
r6cepteur d cristal. C'est 1'6couteur qui modifie les impulsions
6lectriques en sons. L'6couteur 6mettra un d6c1ic d chaque petite
impulsion 6lectrique. Beaucoup d' obj ets quotidiens contiennent
une toute petite charge 6lectrique.
Mettez 1'6couteur sur votre oreille. Tenez une extr6mit6 de filnu
dans votre main. Faites toucher l'autre extr6mit6 nue du fil d cer-
tains objets de la maison : un robinet, un cadre de fen6tre en m6tal
ou un radiateur.
AVERTISSEMENT : Ne mettez pas le filen contact avec une
prise murale ni avec une prise de lampe, ni avec tout ce qui con-
tient de 1'6lectricit6.
AVERTISSEMENT:
Ne touchez pas le fil d une prise murale ou d une prise de la
lampe, ou ir tout ce qui porte l'6lectricit6.
B. La diode ir cristal
Le cCIur de votre r6cepteur d cristal, c'est-d-dire la partie qui
contient le cristal, est la diode. Faites preuve de beaucoup de pru-
dence en ouvrant le paquet qui contient la diode de cristal ! Les
diodes sont faites de verre et peuvent se briser.
Une diode est un appareil6lectrique qui permet au courant de
passer dans un sens seulement. La raison pour laquelle il s'agit
d'un 616ment important est complexe. Il sera possible d'en ap-
prendre plus d ce sujet plus loin, dans la section intitul6e : << Com-
ment fonctionne le r6cepteur >.
I1 est possible d'observer de prds la diode i l'aide d'une loupe. A
l'int6rieur du tube de verre se trouve un minuscule point qui cor-
respond d un cristal de germanium, l'un des m6taux les plus rares
au monde. Un filtrds fln s'appuie sur lui. Pouvez-vous voir le
cristal et le fil ? (Voir Fig. 1)
15

IL
Assemblage du r6cepteur
A. Pr6parer la bobine du syntonisateur
1. La premidre 6tape de l'assemblage du r6cepteur d cristal est
l'enroulement du fil sur la bobine du syntonisateur. Commencer
avec la bobine de fil. Retirer le ruban adh6sif et trouver l'extr6mit6
du fiI. Fig. z
2. Glisser un dlastique de
caoutchouc autour d'une
des extr6mit6s de votre
tube de bobine. Le glisser
jusqu'd environ 1,3 cm de
1'extr6mit6 du tube.
(Fig.2)
coil tube
B. Enroulement du fiI sur la bobine
Remarque : L'aide d'un adulte est recommandde pour la
rialisation de cette tdche. L'enroulement dufil
sur la bobine doit Atre effectud minutieusement et avec
prdcision pour que
le rdcepteur fonctionne Fig, s
1. Enfiler un crayon dans la bo-
bine de fil. Placer les deux extr6-
mit6s du crayon sur deux livres
trds 6pais. Placer ensuite deux
autres livres sur le crayon afin de
les maintenir en place. La bobine
doit maintenant rouler librement
sur le crayon. (Fig. 3)
2. Tenir l'une des extr6mit6s de la bobine sans trop la seffer en plagant
le pouce sur le fil de la bobine.
Tourner alors le tube de bobine avec Fig. 4
l'autre main. Garder le pouce sur le des-
sus du fil en le guidant pour qu'il se place
d plat en formant une surface lisse sur le
tube de bobine. Le fil doit 6tre enroul6
afin de n'avoir qu'une couche d'6pais-
seur, avec les autres parties du fil qui sont
plac6es sans contraintes les unes d c6t6
des autres. Les fils doivent se toucher,
mais ils ne doivent jamais se chevau-
cher les uns sur les"autres. (Fig. a) t6
-".- rubber band

3. Une fois i la fin du fir, terminer l'enroulement de manidre d ce le d6but
et.la fin du_ fil soit placds du m0me .Oig Ou
tube de bobine. S,assurer
de laisser au moins
7,6 cm de fil ddpasser Fig. 5 --.,--..7 rubber bands
d l'extr6mit6 du tube. -------=* /
(Fig. s)
4. Glisser une autre
bande 6lastique sur le
tube et le fil afin de
maintenir l'extr6mit6 du
fil en place. S'assurer
-.- 3 in. (7.5 cmJ
que l'enroulement e.st soigneusement.ry:lu6 et que re fil est bien serrd,
et placer la bobine du synlonisateuiie cOte.
C. Pr6paration de la base et insertion de la bobine
1. Placer la base de plastique face au sol, de manidre d ne pas voir les
lettres et les mots imprimds. *.td f.fineau carr6 arridre vers le haut et
plier les deux langue^ttes vers t,inteiiSui.
2' Plier maintenant le.s deux panneaux lat6raux vers le haut. S,il reste des
:::i1t9_.- plastique aans tes pannlau* laterau,,, rilpl#;t les enrever
et lesJeter.
3- Plier les larguettes pour les ins6rer dans les panneaux rat6raux. Les
tnserer dans les fentes-des languettes du panneiu arridre. S;urrrr., qu.
les languetres soient bien verr6uir-rG.], piu... d;;;;;rant de plier le
panneau avant.
4. Glisser une des exh6mit6s de la bobine
dans l'un des c6t6s de la base- Ciis.e, '^
-l'autre extr6mit6 dans l,autre "Ote J"lu
base.
5. Tourner la bobine de manidre d ce que
les fils.soient prds du trou n a. i* j..
cotes de la base et du trou B de l,autre
c6t6. (Fig.6)
Fig.6
l7

Glisser un des fils d travers le trou B. Enrouler cette extr6mit6 du fil en
la passant deux fois parle trou B et la couper.
6. Glisser l'autre fil d travers le trou D de l'autre c6t6 de la base. Ne
PAS couper cette extr6mit6 du fil.
7.Lefil de la bobine est recouvert d'une mince pellicule isolante fait de
plastique clair. cette pellicule empcche le courant 6lectrique de passer.
I1 faut retirer cette p_ellicule de la partie du fil de la bobine qui pisse par
i travers le trou D. Voici comment proc6der :
A. Replier votre_morceau de papier abrasif sur lui-m6me en pla
qant le c6t6 abrasif vers l'int6rieur.
B. Placer environ 2,5 cm du bout du fil de la bobine de trou D
dans le papier adh6sif replid.
C. Presser le papier adh6sif et retirer fermement l,extr6mit6 du
fil hors du papier adh6sif. Efflectuer cette op6ration au moins
dix fois. Continuer de tourner le fiI. Sabler f isolant jusqu,d
ce qu'il disparaisse.
D6poser le papier adh6sif. Il sera encore utile plus tard.
D. Pr6paration de I'6couteuro de Ia diode et des fils de connexion
1. D6rouler les deux fils des 6couteurs qui sont tordus l'un avec l'autre,
de manidre d ce que chaque extr6mit6 dis fils mesure environ 15 cm de
long. Faire un neud de manidre d ce que le fil ne puisse plus se d6rouler.
2.Faire une petite boucle d l'exk6mit6 de
chacun des fils de diode en les enroulant
autour de la mine d'un crayon. (Fig. 7) Les
boucles devraient pouvoir se glisser i l'extr6-
mit6 d'un des boulons fournis avec le kit.
3. Faire une petite boucle i l'extr6mit6 de chacun
des fils de connexion, comme fait avec la diode.
E. Placer l'6couteur et la barre de r6glage sur la base
1. Placer un des fils de 1'6couteur dans le trou D et le faire ressortir
par le trou C.
2.Faire la m0me chose avec l'autre filde l'6couteur de l'autre c6t6
de la base. Le placer dans le trou B et le faire le ressortir par le
trou A.
18
Fig.7

3. Faire une petite boucle d l'extr6mit6 de chacun des fils des 6cou_
teurs en les enroulant autour de la mine d,;;;;t;.
4. Pousser la barre de rdglage dans le trou 1. pousser un peu la barre
dans le trou et ins6rer talolle a" ryntoriruiionlffi;# Sisuite la
barre au fond jusqu,d ce qu,elle peiret " aur.-f. t.o;;:' -"'
5. Tourner la barre de r6glage- de manidre i.ce que l,eillet soit arign6
il?fJ:ru 4. Le r6cepteuidevrait ressemblei'aui d.;;i"r;", Fi?:-
Fig. sa
Icft side Fig. sb
fright side
F. Connexion des fiIs
Il est maintenant possible de connecter les fils.
1. Placer l'extremit6 d'un des fils de connexion sans la boucle dans
le trou D et le faire ressortir par te irou C.
l.Prgoargr u_n boulon en y insdrant une rondelle. Glisser ensuite les
boucles des fils suivants iur le d;i;;;
- le fil de connexion
- le fil de l'6couteur le plus nrds
- le fil de la bobine
3. Glisser la deuxidme rondelle et ins6rer le boulon dans re trou 5.
Toutes ces op6rations peuvent devenir compliqu6es. Travailrer
Ientementet^minutie"3.-"ni.ri..ipr.rin-r.'d,j,;;ir;;i
t9