A hundred years ago this month, the October 1919 issue of Radio Amateur News showed how to make this receiver (that is, a replacement for a headphone) for wireless use. It was said to provide a bit more volume than a standard headphone, allowing its use on the table, rather than strapped to the ear.

It consists of a phonograph reproducer attached to a steel piano wire held taut above a coil. The tightness of the wire, the number of turns of the coil, and the distance from the coil to the wire were subject to experimentation.

The cone was optional, but would produce more volume.

For more ideas on homemade speakers and headphones, visit our posts on
piezoelectric speakers, a homemade magnetic speaker, and homemade microphones.