Reader Palle Dahlstedt sent in this video that captures a live performance on a custom built instrument, using a pencil drawing as a gestural interface for controlling complex analog synthesis (on a Bugbrand Modular).
Here are the technical details:
The instrument works by creating a voltage potential field in the graphite/pencil markings on the paper using custom movable electrodes made from coins. Control voltages are extracted from other points on the paper, controlling various aspects of the synthesized sound.
The sound is recorded directly from the BugBrand Modular (with a slight reverb), and from contact mics on the pencil sharpener.
“There is no normal microphone,” notes Dahlstedt, “which explains the slightly awkward silence in the beginning, while I’m drawing.”
This is an interesting alternative to traditional control devices and makes great use of everyday technologies.