Switching on the Code

The ability to send a message through electrical wires depends upon opening and closing a switch. When the switch is closed, the circuit is complete and electricity flows. When the switch is open, the circuit is not complete and electricity does not flow. By opening and closing a switch, you can turn communicating devices that depend upon this electrical current "on" and "off". Here's how: 

 
1 bulb (1.5 V) with holder
1 "D" cell with holder
Bell wire
Wire strippers
Paper clip
Brass fastener
Foam core (size of playing card)


1. First you need to construct the pressure switch (telegraph key) that will open and close this circuit. To build this circuit component, bend open a metal paper clip.

2. Use a fastener to anchor the paper clip in a scrap of foam core as shown here.

3. Anchor a second fastener in the foam core, but position it just beneath the bent up end of the clip.

4. Assemble a circuit using this pressure switch, "D" cell with holder, and bulb in holder as shown here.

5. Work with another student who has assembled a similar pressure-switch circuit. Use longer lengths of wires to distance each switch from the light that it controls.

6. Use the Morse Code system to communicate using these devices. First, send simple messages. Then, increase the sophistication of your coded communication.

 

 

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