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I
have been
listening
stories
from dad
that he
made a
radio when
he was
little
younger
than me.
It was
hard
to digest
that his
radio
worked
without
power! I
thought, its
nothing
more than
those
interesting
old stories
that we
have been
told at
bed time!!
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However,
Understanding
little
more about
radio
waves
&
basic principles,
I realize
that dad's
story
could be
true &
it was worth
giving a
try to see
if it
works. So, I
decided to
make a
crystal
radio for
myself.
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The
Basic
Crystal
Radio is
just this
much:
A
coil,
Variable
capacitor
to tune
frequency,
a crystal
Diode and
a High
Impedance
headphone,
makes a
crystal
radio.
You
require a
very good
antenna
and good
ground.
The .001
capacitor
is to
remove
radio
frequency
from
signal
& get
audio only
for
phones.
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In
this
project, I
am using above
circuit
already, for those
interested
only up to this
level. So
that a
crystal
Radio
remains a
crystal
radio in
its
original
form. You
have an
option to
use High
Impedance
earphone
and listen
this radio
without
power. |
 |
However,
in
addition
to basic
circuit, I
decided to
add some
amplification
for the
very basic
reasons
that, it
was hard
to find a
High
Impedance
earphones
and
second, it
was more
pleasant
to listen
to a radio
thru a
speaker.
 |
An
Op. Amp was
added to
increase
level of
crystal
signal so
a low
impedance
earphones
may be
used and
an audio
IC was
added to
drive a
small
speaker. |
Please
go thru
the
Crystal
Radio
Document
given
below for
more
details.
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