Wireless World Carbon Microphone

In January 1935, Wireless World magazine publised an article which described in detail how to build a working transverse current carbon microphone from scratch. In our collection we have several carbon microphones which have most likely been built by amateur radio enthusiasts following these instructions, some of which are pictured above.

The design is very simple - the body of the microphone was built from a resin-free hardwood or another insulator, which housed a pair of carbon rod electrodes that in turn were connected to two terminals at the rear of the microphone.

A cavity was chiseled out between the rods and packed with fine carbon powder, and a sheet of mica glued to the front as a membrane. Ideally the assembled microphone was mounted in a suspesnion ring, although it would work perfectly well sat on one's desk.

Some professionally built models look suspiciously like this design!

If you know anything about these microphones, please get in touch! And if you want to give it a try then you can download the instructions in the link below.

How to build a Carbon microphone, from Wireless World, January 1935.