The Carbon Microphone
The carbon microphone, like the one seen above, is one of the earliest microphone types, and most of the microphones below were manufactured in the 1920s and 1930s.
The initial design for carbon microphones used a platinum bead which pressed against a hard carbon disc. Later models, like the ones in Mr. Steele's collection, were more likely to utilize loose carbon granule elements instead of the hard carbon disc. This later model has dominated telephony, though not broadcasting, up to the present. This type of microphone was outshone in the area of broadcasting by later inventions which provided much better sound quality.
At right is the diagram Francis Blake, inventor of the loose carbon granule microphone, submitted when he applied for a patent on his design.
In the gallery below are most of the carbon microphones contained in the Steele Collection. Though the manufacture years for most of these is known, more precise dates are known for only two of these; the RCA Type 1, manufactured around 1920, and the Westinghouse Carbon microphone, manufactured around 1921.