The concertina is a free reed instrument, invented around 1829 by Charles Wheatstone. They have a number of buttons at each end on plates, connected by a flexible bellows.
Notes are sounded as the buttons are depressed whilst moving the bellows in or out to create an airflow over the reed or reeds.
Note that a concertina has buttons in line with the bellows and reed pan. While accordions have buttons (or keys) at right angles to the bellows.
Concertinas are typically "threepenny bit" shaped i.e. polygonal (6, 8 or 12 sides) but can be (rarely) square or circular. The most common being the six sided variety. The nearer they are to circular, the more prone they are to rolling off tables.
There are different types:
- Anglo, which is of German descent and sounds a different note on push and pull. are diatonic and may have a chromatic scale though they are commonly in the Key of C/G though D/G is also common. It was created by Mr. lachenal after seeing the German Chemnitzer Koncetina at a Worlds fair during the early years development.
- English, chromatic, monosonoric (same on push and pull) and usually can be found in the forms of a Treble, Tenor, or Bass instrument. With some models covering more than one.
- Duet, is chromatic instrument that is set up to allow harmony to be played on one hand (the left normally) and melody on the other (right normally). They are also monosonoric and the two most well known key layouts are Maccann and Hayden.