Steve Conner created this visual instrument for a Danish art group and it’s basically “an adaptor board that [is] connected [to] internal tone generators on a Roland JX-8P synth”. Two videos after the jump.
The board converted the volume envelope to burst length, so the harder you pounded the keys, the bigger the sparks got. Hitting a high pitched note hard would blow the fuses, and the MIDI arrangements had to take this into account
[via Hacked Gadgets]