<. The clavichord is a keyboard instrument that makes sound by pressing a metal tangent against a wire, thus exciting waves and defining the sounding length at the same time. More than any of the other usual keyboard instruments, the quality of the sound depends on details of the key velocity, and the force that is maintained on the key as the note sounds.
It would be interesting to:
* Put sensors in keys to measure force.
* Sense key position.
* Add an actuator, model force and simulate action.
* Connect force and sound, model sound production.
####Week of March 15. Make a rough prototype of sensor/actuator/key
I made a solenoid using 3D printed spool and steel strapping. I was impressed by the quality of [this Youtube video:](https://www.youtube.com/watch?v=DvHiPvuWDPg)
Some things about solenoids:
* Power and time constant are a function of geometry, not wire radius.
* Choice of wire radius determins the tradeoff between voltage and current. Turns out that for my geometry, wire diam. of 0.015" or so gives a few ohms of resistance.
* Return path is important. It adds force, and also creates instability (Earnshaw).
Below are pictures of my solenoid. Without return path 1A gives 0.3 N. With return path 1A gives 1 N. More details will follow!
Used a hall sensor for distance measurement. Also want to explore capacitance - first attempt at this unsuccessful.
Connected sensor and solenoid programmatically and electrically to make an action roughly equivalent to harpshichord keystroke.
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