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Telegraph Science Project



This telegraph science project article provides information on how a telegraph works, step-by-step directions on how to build a telegraph, and a Morse code chart with instructions on how to use Morse code on your telegraph project.

Introduction

In this project, students build a telegraph and then extend their learning in several ways.

Build a Telegraph

In this project, students make a simple telegraph. A telegraph has three main components, all connected by wire: the battery, the key, and the sounder. The battery supplies voltage when the key is closed, setting whatever sounder mechanism you use into operation.

To put it another way, when you press the key, the circuit is completed, causing electricity to flow from the battery through the coil of the sounder, which will click as the metal hits the head of the nail that forms the center of the coil.

SAFETY WARNING: Caution is required when working with electricity. Adult cooperation and supervision are recommended. Use these instructions at your own risk.

Materials

  • Coil of insulated wire, 22-30 gauge
  • Plastic coated hookup wire
  • 2 “D” cell flashlight batteries
  • 2 “D” Battery Holder (for example, Radio Shack model 270-386)
  • 4 small screws and matching screwdriver
  • 6” x 12” (15.25 x 30.5 cm) base board
  • 3” (7.5 cm) iron nail
  • 2 flat strips of sheet metal, 1 ~ 7” (17.75 cm), the other about half that length
  • wire strippers (scissors can be used instead)
  • 2 small pads of paper
  • 2 pencils or pens

Directions

  1. About 4” (10.15 cm) in from one short end of the board and centered, tap in one of the nails.
  2. Leaving a tail of about 5” (12 cm) of wire, and starting at the base of the nail, wind 100 turns of insulated wire neatly around the nail, leaving the finishing end trailing from the base as well, after giving the two ends two twists to unite them. Use the wire strippers to strip away about 1” (2.5 cm) of insulation from each wire end.
  3. Bend the longer strip of metal into a L-shape with 1 90º angles: make the base of the L only about 1 ½” (3.8 cm) long.
  4. Between the nail and the closest short edge, also centered, but about 2” (5.1 cm), use a screw to attach the base of the L to the board, with the part that rises up towards the nail.
  5. Bend the L’s riser at a 90º angle so that it extends over the nail with the coil of wire. It should be about 1/8” (3 mm) above the nail. This is the sounder.
  6. Place the board so a long edge faces you and the nail is closer to the right-hand short edge. Put the batter holder above the board with its black wire trailing to the right and its red wire trailing to the left.
  7. In the upper right-hand corner of the board, about ½” (1.25 cm) in from each edge, screw in one little screw, leaving some of the neck exposed. Wrap the shorter trailing wire from the nail and the black battery wire under the screw head so that metal from each is touching the screw. Tighten the screw.
  8. In the lower left-hand corner of the board, about ½” (1.25 cm) in from each edge, screw in one little screw, leaving some of the neck exposed. Wrap the longer trailing wire from the nail under the screw head so that metal from the wire is touching the screw. Tighten the screw.
  9. In the upper left-hand corner of the board, about ½” (1.25 cm) in from each edge, screw in the shorter strip of metal, attaching the red wire from the battery holder before tightening it. Bent the metal strip into a very shallow Z so that it lies along the short end with its tip over the screw in the lower left-hand corner, but not touching it. This is the Key.
  10. Insert the batteries into the battery holder, paying attention to the positive and negative indicators.
  11. Test your telegraph by tapping the key.

Extend Your Understanding of the Telegraph

In this section, students extend their understanding of their observations by making alterations to their basic project.

  1. Adapt your design by hammering in a second 3” (7.5 cm) iron nail so that it’s head extends over the near edge of the sounder close to the tip, so that the sounder will strike it when it is released from the coiled nail to help you distinguish the dot from the dash (the second sound will come sooner for a dot, longer after the initial sound for a dash).
  2. To make dots and dashes even easier to distinguish, replace the sounder with a buzzer. The red wire will be positive and the back wire, negative.
  3. To be able to operate your telegraph soundlessly, replace the sounder with a light. Your dots and dashes will then be conveyed by longer and shorter flashes of light.
  4. Change the number of coils on the magnet. How does this affect operations?
  5. Create two connecting telegraphs to make a communications system. Note that the key must be pushed down on one set to receive from the other: this is like a walkie-talkie with a listen button as well as a talk button.
  6. Create a model to show how the ability to telegraph changed communication.
  7. Compare the use of the telegraph to the use of one or more of the following: Braille, smoke signals, drum signals, maritime signal flags, semaphore signals, and signal fires.
  8. Write a history of Morse code.

MORSE CODE

A dot is a short burst - create it by clicking the key and immediately releasing it.

A dash is three times as long as a dot, so hold the key down before releasing.

Spacing follows this pattern - space between letters is the same length as a dot, while space between words is the same length as a dash.

If you want to say Morse Code out loud, say dah for a dash, di for a dot at the beginning or middle of a word and dit for a dot at the end of a word. And if you want to use Morse code with someone who is not an American, check out International Morse Code.

American

International

A . _

. _

B _ . . .

_ . . .

C . .    .

_ . _ .

D _ . .

_ . .

E .

.

F . _ .

. . _ .

G _ _ .

_ _ .

H . . . .

. . . .

I . .

. .

J _ . _ .

. _ _ _

K _ . _

_ . _

L _____

. _ . .

M _ _

_ _

N _ .

_ .

O .   .

_ _ _

P . . . . .

. _ _ .

Q . . _ .

_ _ . _

R .    . .

. _ .

S . . .

. . .

T _

_

U . . _

. . _

V . . . _

. . . _

W . _ _

. _ _

X . _ . .

_ . . _

Y . .   . .

_ . _ _

Z . . . .

_ _ . .

1 . _ _ .

. _ _ _ _

2 . . _ . .

. . _ _ _

3 . . . _ .

. . . _ _

4 . . . . _

. . . . _

5 _ _ _

. . . . .

6 . . . . . .

_ . . . .

7 _ _ . .

_ _ . . .

8 _ . . . .

_ _ _ . .

9 _ . . _

_ _ _ _ .

0 ______

_ _ _ _ _

Not for publication: my records.

miniscience.com

yesmag.ca

chss.montclair.edu

home.clara.net

morsecode.scphillips.com