We’ve previously reported on projects involving light-beam communication. It’s relatively simple to modulate an electric light, and receive it at a distance.

Fifty years ago, the February 1976 issue of Popular Electronics carried an interesting article by Forest Mims on the same general subject. But this project recreates the work of Alexander Graham Bell in 1880, the photophone. Bell was the first to communicate a voice wirelessly, but his transmitter (and the one shown in this article) is powered only be the sun. It consists of a mirror, to which is glued a short tube into which one can speak. The mirror is mechanically vibrated by the sound.

The receiver is essentially identical to the ones we’ve shown in the past. It consists of a photocell fed into an audio amplifier. With the use of a parabolic mirror at the receiver, or a Fresnel lens, ranges of hundreds or even thousands of feet can be achieved.

Students looking for an interesting science fair project couldn’t go wrong duplicating Bell’s early accomplishment.