How to Make/Build a Crystal Radio

Step-by-step instructions for making a tunable crystal radio. This is a radio that gets its power from the radio waves. I made it almost entirely from junk except for the diode (1N34 germanium diode) and the earpiece (though you can use a speaker from a phone instead.) The capacitor is made from aluminum foil and a paper towel roll. The coil is rolled on a toilet paper roll. The wire is enameled magnet wire. For the antenna I use a 15 foot wire laid out on the floor. For the earth ground I connect a wire to the ground in the household wiring.

I originally got this circuit from the book "Radio Receiver Projects You Can Build" by Homer L. Davidson.

For this circuit, the diode must be germanium. The following is a partial list of germanium diodes that should work:
1N34A, 1N60, 1N91, 1N119, 1N270, 1N277, 1N283

The following are not germanium diodes and may need a long antenna or a powerful radio station nearby to work:
1N4148 (silicon, found on a lot of circuit boards), B16 (zener diode), 1N5060 (avalanche diode)

The crystal earpiece (piezoelectric earphone) and/or 1N34 germanium diode and/or air core variable capacitors can be ordered from most of these sources:
http://www.midnightscience.com
http://www.scitoyscatalog.com/categor...
http://www.maplin.co.uk/p/mono-crysta...

You can find the circuit diagram shown in this video on this page:
http://rimstar.org/equip/crystal_radi...

See also:

How a Crystal Radio Works
http://youtu.be/0-PParSmwtE

Crystal Radio Troubleshooting and Tips
http://youtu.be/HZZmKZJrIW0

Make Crystal Earphone/Earpiece for Crystal Radio
http://youtu.be/OVapqz4yBCY

Use Earbuds/Earphones with Crystal Radio
http://youtu.be/GCh2LVHUavQ

Make a Crystal Radio Coil with Taps
http://youtu.be/Gi9EmhrcfIg

Make Razor Blade Diode for Crystal Radio/Foxhole Radio
http://youtu.be/eIdHsjfbckw

How to Make Crystal Radio Amplifier for Speaker
http://youtu.be/JtPwxbOgBHw

How to Make Amplifier for Crystal Radio Earphone
http://youtu.be/cQ-LxMDrD_o

Steps for How to Make Amplifier for Crystal Earpiece
http://youtu.be/V0dKdSNv_dY

How to Make an AM Radio Transmitter (so you can transmit to your crystal radio)
http://youtu.be/_4-Sx-T6VBc

Amplitude Modulation with Simple AM Radio Transmitter
http://youtu.be/R04yEKqgGPc

Follow me on Twitter:
https://twitter.com/#!/RimStarz

- http://rimstar.org

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Closed Caption:

hey guys a few weeks ago a friend of
mine asked me to show my crystal radio i
made which is this one right here made
many years ago and since then i played
around with other variations and even a
kit then I looked around YouTube and saw
that there was no video that really went
through step by step how to make a
crystal radio so i figured i'd make one
using as much scrap pieces as I could
so here's the video hope you enjoy it
here's the complete circuit diagram but
don't worry you don't have to understand
in order to make this the parts we'll
have to make our this capacitor and
these two coils
so let's start with the capacitor can
make the capacitor will get some
aluminum foil is we're going to cut to
six by six pieces
there we go ok the first piece of foil i
simply taped onto a paper towel roll
using masking tape use any kind of tape
you want as long as it's not
electrically conductive tape and i left
about a half inch of the bottom here one
centimeter for the other piece of
aluminum foil cut a seven by seven piece
of white paper and tape the aluminum
foil onto the middle of it
here we go mixtape that piece and tape
it's that it's wrapped around paper
towel roll make it so it's snug fit but
so they can slide up and down fairly
easily
you want the aluminum side facing out so
that the paper is facing in that with
papers between this aluminum piece and
the piece that you previously take on to
the role
also I'd ass it's just at the paper be
seven inches by 7 inches and that's
because I knew that that if it's seven
inches that paper would fit completely
around paper towel roll because you want
this aluminum insulated from this into
aluminum next cut a piece of wire about
1 foot long and strip about an inch long
piece of insulation off one end of it
give a little bit of a 90-degree turn
their and tape it to the top corner is a
free moving piece of aluminum foil
the peace the tape just make sure fairly
snug there want to move around and then
cut another piece of wire the same way
and strip at the same way and take it to
the bottom of the piece of foil that
doesn't move
there we go there's our completed
capacitor
now I'll show you how to make the two
coils ok for the coil
i'm going to use this I try to keep her
all right here
I make sure your fingers off so you'll
get all the toilet paper and glue and
stuff the sticking up off it for the
wire for all kinds of wire here
this is magnet wire it's a thin wire
about what on all 22 24 26 gauge and
it's covered in an amiable installation
this we kind of resin or something
that's called a magnet wire and reasons
call my wires use for making
electromagnets about this from radio
shack in the package of different ones
can also use wire like this with the
thicker insulation but it is going to
take up more room mom
when you wind down the coil and then
I've got this big spool right here which
1 i'm actually going to use a long time
ago i'm never going to use to completely
it's 26 gauge
that's a wire to use ok to start for the
coil when I suggest this is a technique
that works well for me take a piece of
masking tape or whatever take they're
using and I cut it to the complete left
of the the toilet paper roll
stick it on there for the back if you
want
ok and then take another piece just like
that and do again
ok for the first winding is the primary
and that's the one that the wire that
the Italian antennas can be attached to
the tree in put water on to boil
i'm going to start it fairly close to
the edge and it said to hold it in place
peel back the tape and put in place
I'm going to leave about a white and a
foot or so wire sticking out with them
ok so ready to start their 25 turns
okay there we go
left about a foot right here on the end
and set this up i'm doing this is just
want to point out the direction that you
start first coil the coil really matter
as long as both cause you're going to do
or while in the same direction
let's have lifted the tape put it
underneath there
I believe very close to the other
windings and put the tape back
there we go that's the first one now to
work on the second coil
ok second coil secondary is 90 turns 90
and you want to start it
one eighth of an inch away from the coil
you just did
that's quite close to 90
ok the next step is to make a good
holder for all of this
and so I got this literally pieces of
scrap wood and I script piece of as you
can see scrap with the here and then on
the back
I also screwed some more if you
subscribe were together the whole idea
is it goes like this you take the
capacitor
and just slide it on like that so for
adjusting a capacitance you can just
traipse through that you put a thumb
tack there now for the coil you're going
to need some way of tuning this coil
because it's a tunable crystal radio for
that I've got this sort of thing
what is this well this is simply a piece
of paint can I took a piece of cake
paint can and cut it up and cut a piece
of metal to this shape that way I can
make a wiper blade
I simply put a little screw here and
screw that to the top of that that's so
I just basically bend it into a V shape
that way where whites against the coil
air
it's a not very smooth but pro slippers
but it comes to a point
ok so the next step will be to find out
we're going to put this probably around
there and put some tax just to hold it
in place and I've got to sand the top of
the coil right here
but when you send the top of the coil
that makes contact with the blade when
you send the topic will you want to make
sure you don't short out one wire to the
next wire
so when you sand you really just want to
send the very surface of the wires but
not be between the wires
ok i just take the coil down there you
can see it in this result next step is
to start hooking up some wires here
first thing we'll need is a ground wire
connection for that i use this trick
right here
what I do is I have a North America we
have plugs like this
this problem right here on the plug is a
ground connection and these two are hot
and neutral but i only want to use this
one so i bought a plug that you can buy
at hardware stores and then I can't get
up just a single wire to just this
ground connection and i'll plug it into
this extension cord and I tested this
wall socket that the extension cord is
plugged into it does in fact have a good
ground connection so I'll just need to
take that up here somewhere
some other suggestions for our ground
connections you can connect to your hot
water pipes
your water pipes underneath your sink
you get a radiator you can connect to
that anything that's connected to ground
it's the next I need an antenna and for
that you simply take a long wire and
string it up about 15 feet long so I'll
tape that in place probably right here
next I need a diode
this is a one-in-three for diode
germanium diode works quite well I've
tried a few different ones and notice it
has a gray strip stripe along one end
here
that's important for positioning this
thing properly so I'm just going to take
that into place
I'll take it with the striped facing
outwards from it
the last piece will need is this your
piece right here
it's a two thousand ohm earpiece very
very sensitive
some people use speakers from phones as
well so if you dig up an old phone you
might want to try that
just realized I forgot to mention a very
important step and that's to bear these
wires right here
so the way I usually do that they simply
take exacto knife and just scrape like
that
very gently you don't want to cut the
wire and do that all around you just
need to take the insulation off the
enamel just like we did when we sanded
the top of it other ways of doing this
are to use sandpaper and there's also
something you can dip it in and I don't
have to acetone or something that just
dissolves the enamel
ok I've done all four ends right here
all four pieces enameled wire
ok now to start putting it together and
start over here with the ground
basically just follow the diagram
I just twist things on twist the mac
very tightly lots of turns
materials at least LOL i like to put the
enamel ones on first
you can wire first because the other
wires then wrap around this tightly
and one more wire I need to go from the
wiper blade to ground as well so i'll
have to make a wire for that
ok not a test
ok to adjust it you adjust the wiper
first to hear something
if you don't hear anything at all then
just keep moving this back and forth but
and then once you find something adjust
the volume using the capacitor
I got something and just put that in the
camera microphone so you can hear -
anyway there you have it the crystal
radio made mostly from junk
the exception of the diode and the
earpiece
well thanks for watching be sure to
check out my youtube channel rimstarorg
for more science and tech videos
including more crystal radio related
ones
also be sure to subscribe if you like
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leave a comment or question below see
you soon