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Simple Telegraph

Telegraph was the choice of long distance communication in early days. In this activity we will build a simple telegraph. Let us say I want to send message ‘Hi’ from Pune to Mumbai. Transmitter at Pune will send electrical signals over wire to Mumbai. Receiver at Mumbai will print the signals. All communication happens in dots and dashes. This is morse code. Telegraph Operators in Pune and Mumbai know how to translate morse code to and from English alphabet. Let me explain how it works. 4 AA battery will act as a power source. This is transmitter. When pressed it completes the circuit and electromagnet is active. It attracts the coin and brings the ruler down. This action results in sketch pen making a dot on paper below. Paper is moving. More time on the paper results in dash. Let us see how to build it. We will use ruler, empty refill and steel wire to form a lever mechanism. Plastic bobbin with screw as a core acts as an electromagnet. Coin attached to the ruler is attracted by electromagnet when signal is received. Counterweight at the other end are responsible from moving away the coin when electromagnet is not powered. Sketch pen at the front marks the moving paper below. Paper moves at a constant speed. We will move it manually. In real telegraph, roller is used. As signals are received, ruler moves up and down. When sketch pen touches paper for longer duration, dash is created as paper is moving at constant speed. Smaller durations create dots. This creates a series of dots and dashes on the sliding paper. Later on, these can be translated to english alphabets as per Morse Code. This is the morse code for english letter ‘hi’. Do try this at home. Music www.zapslat.com #electromagnet #telegraph #207_EM_SimpleTelegraph