code has been around for over a hundred years. For many
before people could talk with one another using a telephone or
many depended on sending and receiving messages using a code of
and dashes known as Morse code. This code was invented by
inventor of the telegraph, Samuel Morse, and its first use was to
and receiving messages over long distances using the telegraph.
quickly realized that Morse code could also be sent my using
lights or signal flags, and ships at sea quickly began using it to
communicate with each other, as did the military.
And when radio
was first invented, the only means of communication by radio was
code as well. It would take several more years to figure out
to send and receive voices over the air. But even long after
voices could be sent by radio,
people still used Morse code to send in receive messages on land
sea, as well as in the air. Morse code was often used
signals could be heard much farther than voice communications, and
as radio communication equipment improved, Morse code was
less and less, and today it has largely been abandoned in favor
of digital signals that can be sent much faster and can carry
But Morse code is not entirely dead.
It is still used and enjoyed by amateur radio operators (also
"hams") around the world. For many years, one of the
of a ham radio license was the ability to send and receive Morse
but in the last few years, most countries have dropped the code
requirement. Still, although hams are no longer required to
learn Morse code to obtain an amateur radio license, many still
the time to learn it on their own. These hams regularly enjoy
communicating using Morse code. In addition, there
are still some individuals and outdoor groups who use morse code
each other using flashing lights or by "wigwagging" signal flags.
you think it would be fun to try your hand at communicating with
Morse code, but you are put off by the fact that Morse
code might take some work to learn. Well, let The Science
staff let you in on a little secret. It is
a little hard to learn, but
not as much so as you might think. And just think of the fun
you can have communicating once you do!
give you an idea of how much fun you can have with Morse code,
going to show you a code known as "tap code" that you can
begin using right
away! Once you have learned to use tap code, The Science Notebook
hopes it will encourage you to learn Morse code! The
to learn Morse code are available right here, and they are free!
Is Tap Code?
code was used by American prisoners of war during the Viet Nam War
to communicate with one another inside POW camps when talking was
allowed. Although American POWs were punished, and sometimes
for talking with one another, they were able to keep track of what
going on inside the camp by means of tap code without their guards
knowing what they were up to.
code is very easy to learn, and it can be sent and
received using many diferent methods including tapping
(naturally), a simple telegraph, radio, flashing lights, and
flags, just like Morse code. In addition, you can use hand
signals, and probably many other ways as well!
So How Does Tap Code
Special thanks to Nyle, K7NS, for
suggesting an important correction to this material!
tap code is based on a 5×5 grid of letters, representing all
letters of the alphabet, with C and K sharing the same code.
letter is represented by two numbers. Take a look at the
that there ia a number at the top of each column on the
chart, and a number for each row on the left side of the
chart. The code for each letter
is found by first locating the letter you want to send. The
for that letter consists of two numbers. The first number is
number in the row
to the left
of the letter, and the second number is the number in the column
above the letter.
example, the two digit code for the letter "W" is 5-2. (The
is there just to show the space between the two numbers.)
first number (2) is number in the row above the W, and the second
number (5) is the number in the column to the left of the W.
The order is ROW first, and COLUMN
can decode tap code as it as it is being sent using the above
the person is not sending too fast. You can also send tap code by
of the same methods you could use to send Morse code.
However, the main
disadvantage of tap code is that it takes longer to send each
than it would in Morse code, but you can even work around that to
Receiving Tap Code
To send a tap code for the letter "W", you would tap five times,
pause, and then tap twice, like this:
"tap tap tap tap
tap (pause) tap tap"
Using dots to represent taps, the code for "COME HERE" would be:
send this message, you would make the number of taps for the first
number, pause, and then tap the second number. Leave a
pause between letters. Be sure to send this slow enough that
other person has time to copy each letter. After a while,
will have memorized the codes for each letter and will be able to
and receive much faster, but never send any faster than you can
receive this message listen carefully for each pair of taps and
down the two numbers. When the sender is done, decode the
by going along the top row to the first number and then straight
to the second number on the column to find your letter!
will take some practice to do this with any speed, but with the
above table, you can
begin to use tap code right away. As you practice, you will
to recognize the number pairs for each letter and you won't have
You may find it a little bit tedious to send or receive one letter
at a time, but we'll show you some shortcuts a little later.
Sending And Receiving Tap Code
you are just starting out, send slowly. You need to give the
person on the other end plenty of time to count the taps and
them down. If you want them to copy each letter as you send
you will also need to give them time to locate the letter.
more you practice, the faster you can send and receive,
but never never send faster than the other person can copy!
sure to leave short pauses between each number in the pair.
longer taps between number pairs, even longer gaps between words,
the longest gaps between sentences.
Remember that the tap code
for the letter K is ths same as for the letter C, so if the
receive is first copied as CNIFE, you should see
that the word is really KNIFE.
If you are copying
tap code and miss a letter, you can send a string of taps.
can also do this if you send the wrong letter.
Other Ways To Send Tap
are not limited to sending tap code by just tapping. There
lots of different ways that will work, particularly once you have
memorized the letters. Here are just a few.
- You can send tap code at night over a long distance using a
flashlight or any other light that you can turn or off
the light won't turn or off easily, you can put a piece of
over the light and flash the light by uncovering and covering
You can also flash the light by moving it from behind a tree trunk
other object and back. In the daytime, you can use a mirror
flash reflected light, although it will take some practice.
Flag or Other Signal
- You can send tap code during the day over a long distance by
flag to send the numbers. A piece of cloth tied to a stick
do fine. Starting with the flag hanging straight down, lift
to your side and back down for each tap. Depending on the
the flag and its color, this can work over a fairly long
distance. You can also make signals using just a stick, or a
stick with a piece of cardboard attached. Can you think of
Your Hand or Hands
- Since it just so happens you have five fingers (or if you
four fingers and and a thumb) on each hand, you can easily send
code just by using the fingers on one hand. Instead of taps,
would simply hold out the number of fingers required for each
Using Tap Code to
that you know the basics of tap code, you can begin using it right
away. Grab a friend and a couple of note pads, decide which
method you want to use, and begin practicing. You can use
camping trips, between rooms at home, or hundreds of other
places. Use your imagination!
Simple Telegraph Set
help you use tap code with sound, you can make this telegraph
set so that you can
send and receive with a friend. With a second set and one or two
cords, you can send and receive a couple of hundred feet or
To make a single unit you will need one buzzer unit
(RadioShack mini-buzzer, 273-0053 or similar); small piece of wood
the base; a battery holder that will hold two C or D cells; 5
metal screws; a disposable aluminum food pan; clip leads or
covered wire. (Clip leads are really good for connecting the
battery and the wires between stations, but you can make do with
The unit shown above uses a homemade battery holder for
C or D cells. You can buy a battery holder at RadioShack or
online, but you can make one for almost no cost following the
instructions found HERE
If you want to buy your own battery holder, skip the next
couple of paragraphs.
you don't have clip leads and will be using covered wire, make the
battery holder as instructed. You can get covered wire for
from an old string of Christmas tree lights. (See more information
the homemade battery holder instructions found HERE
can also use the "zip cord" from a non-working drop cord or
electrical cord from a broken appliance. This cord has two
strands that con easily be split apart. Each side makes a
length of insulated wire,
you have clip leads and want to make the homemade
holder, instead of putting wires on either end, cut two small
from the food container. (You should be able to cut the aluminum
with a good pair of scissors.) Each strip should be about 1/4 inch
than the width of the cell. Tape one strip to the positive
terminal of one
cell and the other strip to the negative end of the other cell.
One end of each strip should stick out about 1/4 inch so
can attach the
clip leads. Finally, place the rubber band around the two
and make certain it pressed firmly against the metal strips.
This will give you a nice tab on each end on which to
buzzers available today are piezo buzzers that
work correctly when attached to the battery one way only. Notice
that the red wire coming from the buzzer attaches to the positive
(+) end of the battery, and the black wire attaches to
or (-) end of the other battery. Black wire almost always
indicates negative and red wire represents positive. The
leads attached to the battery in the above picture follow this
Of course, the color of the wire you use is not
but getting the buzzer hooked to the right ends of the battery is,
the buzzer wires are color coded so that you will get it right.
This particular buzzer will
operate with a voltage of 1.5 to 3 volts. We are using two cells
give us 3 volts because we are building this to work with another
of the same kind and attaching the units with a long electrical
cord, so we
want to use the higher voltage. Touch the (+) end from the
battery holder to
the red wire on the buzzer and the (-) end to the black wire.
The buzzer should
sound. If not, check all of your connections and be sure
have the right wires connected to each end of the battery.
Next, mount the buzzer on the board. You can mount it using
very small screws, double sided foam tape, glue, etc.
cut a small strip from the aluminum pan about 3 1/2 to 4 inches
and 1/2 inch wide. Make a sharp bend in this piece about 1/2 inch
one end. This will be the telegraph key.
three strips of aluminum 1 1/2 inches long and 1/2 inch wide.
Fold each of these strips over the long way to form a two
strip about 3/4 inch by 1/2 inch. Also cut two pieces of
insulated wire about 3 inches long and
strip about 3/4 inches of insulation from each end
of both wires.
the key (the long aluminum strip) at the bent end by screwing it
into the wood
with a sheet metal screw. Before you tighten the screw
completely, wrap the bare end of one of the wires around the
along with the bare end of the black wire from the buzzer unit.
Finish tightening the screw, making sure that the metal
screw and the two wires all make good contact.
sheet metal screw underneath the other end of the metal strip.
This will be the contact for the key. Before you tighten the
screw completely, wrap one bare end of the other
wire around the screw and finish tightening. Make sure the
contact between the screw at bare wire is good.
fasten the other bare end of each wire and a 1/2 by
3/4 folded aluminum strip to the edge of the board as shown
in the photo. The folded end
of each strip should hang off the edge of the board enough to make
good surface to fasten a clip lead. If you don't have clip
you can just fasten the bare wire strips to the board and
other connecting wires later. Some hints for connecting
be found HERE
Finally, mount the red wire to the board using the third folded
strip and a screw.
connect the positive end of the battery to the red wire using a
lead or one of the other ways of connecting wires on the
pages (see above). Connect the negative end of the
to the wire coming from the screw underneath the metal strip.
right now, you do not need to attach wires where the green and
clip leads are shown.
Checking It Out:
If everything has been wired correctly, the buzzer should
when you press the key. If not, check all your connections
against the picture above, and be sure that the connections are
Once it is working properly, you have a nice buzzer set you
use to send or receive either tap code or Morse code. But
real fun, you or a friend can build another unit and connect the
together to make two telegraph stations. Let's see how...
Connecting Two Telegraph Sets
Two telegraph sets made using the plan above; a disposable
food container; clip leads or wire; one or two long outdoor
electrical extension cords;
tape (optional). NOTE: The extension cords will not be
harmed in any way.
The extension cord(s) are used to connect the two sets
While you are using any cord for this purpose, it
should NEVER EVER be
plugged in! Otherwise, you might get a very nasty
electrical shock -
or much worse! If you don't understand this, please go play with
You can use an extension cord with either two or three
Almost all outdoor cords have three prongs - two flat ones
third round one. If you have an extension cord with three
you will only
use the flat prongs.
Connect clip leads or wires to
each telegraph set where the green and yellow wires appear in the
illustration in the last activity. Connect the other ends of
each of these these wires (or clip leads) to the blades
of the plug on
the drop cord. It is a really good idea to hook up to
the plug end first so that you don't accidentally plug
it in later!
Next, after making absulutely certain that the plug end is
attached to the other set
and NOT plugged into the wall, cut two small strips of aluminum
from the aluminum food container about four inches long and not
as wide as the slots in the socket end. Fold each strip over
long way twice so that you have two strips that are each one inch
long. Insert the
folded end of a strip into each of the flat slots in the
you are using clip leads, fasten a clip lead to each strip, being
that the two leads don't touch. If you hear a low buzz, that
means the wires should be reversed.
you are using wire with the ends stripped, tuck the bare end of
wire between the fold of each aluminum strip. Again, if you
hear a low
buzz, that means the wires should be reversed.
Press one of the
keys. If everything is working correctly, both buzzers
sound. Next, press the other key. Again, both buzzers should
sound. If not, check your connections carefully and try
If any of the connections are loose, you can secure them
tape as necessary.
Using the Stations:
Once you have the two stations working, you can move them
different rooms, or even different houses. They can also be
between two tents while you are camping. The longer your
extension cord, the farther you can move them apart. You can
connect two different extension cords for greater distance.
using batteries on both units, and by using two cells to produce 3
volts instead of 1 1/2 on
each unit, these units worked well up to 200 feet. They
might work over a much greater distance, but we only had two drop
can immediately use thse to send and receive tap code, and if you
decide to learn Morse code, two sets connected together will make
learning and practicing a lot more fun!
OK, now that you know how to send and receive tap code and have
several ways to do so, let's learn some shortcuts!
you have ever chatted over the Internet or texted over a cell
you already know a lot of shortcuts you can use with tap code,
such as LOL
for "lots of
You can also use these shortcuts used by ham radio operators who
send morse code:
Send the letters BK
to say you
are finished for now and waiting for the other person to start
Send the letters AR
to say you
have finished your message
Send the letter R
to say you
received the last message
Send the letters CL
to say you
Send the letters AS
to tell the
other person to wait or stand by.
you use the tap code a lot, you can really save time by making a
book. A code book consists of all the shortcuts you
such as the texting and ham radio codes mentioned above. You
can also make thousands of three letter codes to represent words,
or whole sentences. In fact, if you use all the the letters
except K (since it has the same tap code as C), you can make as
13,800 different codes!
- the total number of
possible combinations is 25 times 24 times 23 which eaquals
Let's see how that works.
with the lowest combination of three letters you can make
alphabetically and work your way up. We'll do the first ten.
decide what each three letter group will mean. You can pick
words, phrases or sentences that you use a lot. For example:
- AAA Meet
- AAB At my
- AAC At
- AAD At
- AAE At
- AAF In
- AAI As
soon as possible
- AAJ In
should be able to see that you can send a lot of sentences with
these ten groups. For example, "Meet me at the store in one
can be sent with just three letter groups - AAA AAE AAJ.
would be nine pairs of numbers in tap code.
Of course, you can
use as many words, phrases or sentences as you want, but you
list your letters alphabetically so that the meaning is easy to
find. Also, you don't want to have so many that you spend
much time looking them up. It is best to use only for long
phrases or sentences you send often.
An Example of a Code Book
is a sample code book that uses only two letter
noted above, using three letter code groups, you can make as many
13,800 different combinations, but you would never use anywhere
that many. However, using only a two letter code, you can
almost 600 (25 x 24 = 600) different combinations. You can't
qiute that many, though, because a few of these combinations are
actually words (me, go at, we) or abbreviations used above.
there are more combinations left than you would ever use.
Take a look at these and see just how many different messages you
||End of message
(sent only at the end of the message)
||When sent by
itself, it means wait or stand by
||I am through
sending and waiting for you to respond
||Through sending or
receiving, and I am quitting
||Foot or feet
||Mile or miles
||The word "are," or
when sent in response to a message or part of message,
||Repeat your message
|| Slow down.
||Yard or Yards
(since tap code does not include numbers)
tenses, add a third letter
Add D for
Add W for
= will come
= will send
for perfect tenses
To make plurals, add S
you want to add others, you can. If you don't think you
some of these, leave them off. The idea
here is to make it easier for you to send messages quicker, rather
than harder, so you
probably would not want more than 100.
Complete Phrases or
Part of that hundred
could be complete phrases or messages. In this example, we
with the letter Z because that should alert the person receiving
if this is a three letter code group, it is most likely a phrase
sentence code. If you want to send only two letters, you can
still have plenty of different combination just beginning with the
||Can you come over
to my house today?
||Let's go fishing!
||Do you have a lot
To make the actual code book,
you should list all your codes and abbreviations twice. The
time, they should be sorted into alphabetical order by the word,
or sentence. This list will make it easier for the sender to
the right code or abbreviation. The second list should be
alphabetized by code or abbreviation. This will make it
for the receiver to decode the final message.
If this sounds like a lot of work... well, it is. But it
will help you make tap code really useful.
you have had a chance to use tap code for a while, you will notice
while it is easy, it does take some time to send and receive
simple messages, even using
shortcuts and special codes. However, if you have found
codes to be fun and useful, you can speed things up a lot
by learning Morse
code. Morse code is a little more difficult to learn to
begin with, and it
really does have to be memorized to be useful, but if you take the
to learn it, it will speed things up for you quite a bit once you
Take a look at the International Morse Code chart below.
||di di dah
||dah di di
||di di di
||dah di di
||di di dah
dah dah dah
||di di di
||di di dah
||di di di
||di di di
||di di di
||di dah di
||dah di di
di di dit
dah di dit
dah dah dit
dah dah dah
||di dah di
dah di dah
||di di dah
dah di dit
||di di dit
di di dah dah
||dah di di
notice that each letter, number and punctuation mark is
paper by a series of dots and dashes. Morse code can also be
using sound or light, but unlike tap code, a dot is represented by
short sound or flash, and a dash is represented by a sound or
that is about three times longer. There are several good
and a free podcast class on the Technology section of the Useful Downloads
page that will help you to learn code by either
sound or flashing light. No matter which one you use, you
try to learn every letter as a single sound or flash pattern
trying to count the dots and dashes. You will learn much
Why Is Morse
Better Than Tap Code?
There are several reasons.
tap codes take longer to send. Letters in tap code can
to ten taps. If you study the tap code table, you will see
of the 26 letters of the alphabet only 7 can be sent with four
less, and two of those - C and K - share the same code.
Morse code, every character in the alphabet can be sent using a
combination of no more than four dots and dashes, and most use
less. Also, in Morse code, every letter of the alphabet is
represented since C and K each have their own unique code.
addition, Morse code has codes for each of the numerals, and each
no more than five dots and/or dashes. Morse code also has
punctuation marks, and these require no more than six dots and/or
dashes. Tap code does not have either numbers or
The bottom line is
that takes less than half the time to send letters in Morse code
using tap code, so if you want to use code to communicate, Morse
is much better than tap code, even though it is a little harder to
For other codes you might
find fun, check out the Gilbert
pages. They're old, but the codes are still useful.
you want to learn Semaphore, check out our Semaphore PowerPoints
Also, there's lots more to see and do on our Experiment Pages
or you can
visit The Science Notebook Home