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Insight - How Telephone Works

Table of Contents:

Written By: 

Arpit Jain

“Mr. Watson, I want you here”, Alexander Graham Bell knew so well that he has created a revolution when he said these words after testing his telephone experiment. It was the first of its kind and an invention that revolutionized the way we communicate with people separated by geographic distances and barriers. Years after its invention, telephones have penetrated almost every nook and corner of this world and a large proportion of these connections are landline phones. Once a luxury, telephones aremore of a habit now, indispensible requirement of any 20th century citizen. These devices have been sitting silently in most homes in modest corners that no one seems to question what goes on inside them that they keep on working without maintenance and battery.In this insight, we intend to look inside them to know for sure, what are they made of.

The image above showsa basic telephone. The standard parts of any corded phone package are the base, a handset cord and the handset. The shape of the base and the handset can vary as per the manufacturer. Innovative designs often feature an LCD display and for that require a battery, the one in this insight doesn’t require a battery as it doesn’t have any LCD or similar electronic accessory attached to it.
The base contains the keypad, switchhook, ringer and a small LED that glows whenever the handset is picked up. The ringer is a small speaker that produces a sound when the call comes in. The hook switch is a tilted structure over which the handset is placed. Whenever the phone is not in use, the handset rests over the hook switch. This position is called ‘on hook’ and the circuit that brings the tone to the handset is open. When the handset is picked up, the telephone goes’off hook‘and circuit is restored to its closed position, thus giving a dial tone.
The images above are the bottom and the side views of the phone. On the bottom, an input jack for line-in and switches for the ringer volume and tone-pulse selector are there. On the side, a jack for connecting the handset cord is there.



Thank u very much for providing all the details..i request u to provide schemetic of internal circuit of telephone so that it will become easier to understand..