We touched on harmonic table MIDI controllers when [aris] was building one. [Ken Rushton] has one of C-Thru’s industrial keypads, the AXiS-49, as well as disassembled the gadget to show how it works. A PIC18F2450 microcontroller supplies the USB interface as well as is connected to a dsPIC33FJ128GP310 digital signal controller which decodes the keypresses. The membrane buttons are made with two concentric graphite disks that touch gold contacts. The microcontroller procedures the time between the two points contacting to figure out the button velocity. monome button clones likewise use circular get in touch with pads, however cannot determine velocity since they only have one element.

[via Matrixsynth]