If I was young again I’d learn to make clavichords and play them. Here’s a video showing one, giving a good look at how the simple mechanism works. It’s a series of keys, the ends of levers that cause a blade of copper, called a tangent, to touch a pair of strings, producing very quiet, infinitely delicate notes rich in overtones. The few times I ever got to play one proved that it needs the most careful touch of any keyboard instrument.
The clavichord was a very early keyboard instrument. In its earliest examples a pair of strings is touched by up to four tangents, arranged so none of the notes played on that string would have been commonly played at the same time. That saved on the number of strings needed and the size of the instrument.* As the harmonic language of music changed, later versions reduced the number of notes per string to no more than two, one note per string becoming common near the end of the 18th century.
Here are some of the earliest extant keyboard pieces from the 15th century. Three pieces, the first is Conrad Paumann’s setting of the song Mit Ganczen Willen, well known to music majors since it’s found in the universally used Historical Anthology of Music (ed. Willi Apel). The second is (an anonymous piece?) from the Buxheimer Orgelbuch followed by one by the early organist, Hans Kotter. The player is Ernst Stoltz.
Three pieces by anonymous Italian composers.
Two Miserere by William Byrd played by David Moroney
Tombeau de Monsieur Blancrocher by Johan Froberger, a great composer who isn’t known enough these days. The video of cemetery art is gloomy but no more than the magnificently gloomy music, again played by Ernst Stoltz.
There are other videos with pieces by later composers including J. S. and C. P. E Bach played on clavichord. Both are known to have owned clavichords, C. P. E. Bach was famous as a player and composer for the instrument. A lot of J. S. Bach’s instructional pieces fall within the most common range for the clavichord of his time so it’s possible that those were composed to be played on it.
* For more information about clavichords The Clavichord Society of Boston, not the president, but a member. And, this is a case when wikipedia has a pretty decent article on the subject.