The Original Two-Way Radio: The Tin Can Telephone

May 19th, 2016

The most intricate and revolutionary advances in modern technology have had their origins in some of the most rudimentary sources. The two-way radio has become a bellwether of 21st century cutting-edge technology, but what’s now state-of-the-art still has the same fundamental intent as a homemade “toy” many of us played with as kids: the tin can telephone. And while we’re on the topic of radio nostalgia, we invite you to get a bigger-picture view of the cultural impact of the radio. Now that we’re ready to move on, here’s what you should know about the tin can telephone:

History in the Making

Before they were introduced to smart phones, cell phones and wireless technology, kids derived a unique fascination from the tin can telephone. All it took was two tin cans – or paper cups – with the tops removed, duct tape, string, a hammer and nail and any decorative embellishments one wanted to add to create this oh-so-basic version of a two-way radio.

Tin Can Telephone Schematics: How it All Worked

The process of making a tin can telephone would start by turning either cans or cups upside down and hammering a nail through the bottom of each can to make a hole in the center. Then you’d cut a length of string anywhere from 5 to 15 feet long and poke one end through the bottom of one can, knotting on the inside. After doing the same with the other end of the string in the opposite can, you and the person on the other end of the line would each take a can and move apart until the string is taut. When one of you put a can up to your ear, the other would talk directly into the other can, with the sound of the voice being transmitted across the string.

When we speak, our voices create vibrations, which travel down the string, if it is stretched tight enough, and vibrate the bottom of the can on the other end. That then vibrates the air, and those vibrations get transmitted to the other person’s ear.

While this was a common children’s activity in the 20th century, the tin can telephone actually predates the electromagnetic phone. The tin can telephone has also been called the “lovers’ telephone,” and it evolved from experiments conducted by Robert Hooke, an English inventor and physicist in the 1600s.

Categories: Two Way Radios

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