Exploring the Yamaha BC2 Breath Controller

Rubber ‘bladder’ connected to the breath input with
a magnet in the center which ‘drives’ the hall effect sensor IC3 

This is the other side of the bladder. It is sealed by the bottom of the BC2 case.

Component Side of Yamaha BC2 Breath controller. IC3 is in the very center
and is a hall-effect sensor which increase it’s output as the magnetic field above it is increased. 

IMG 1731

This is the inside of the headpiece showing where the PCB sits. The teardrop shaped 
feature seals the rubber bladder while the “+
”  in the center preloads the
rubber bladder so it sits close to the hall effect sensor on the PCB. 

The “top side” of the PCB. Output cable is in the lower right corner.

It is not well documented, but the Tip (red wire) of the stereo plug is ground, the Sleeve (black wire) is +Volts and the Ring (white wire) is the output voltage.