Jaw Circuit

Jaw
Here's the circuit I developed to work with the jaw transducer. The sensor is a linear Hall-effect unit from Allegro MicroSystems (allegromicro.com). Its output is amplified to the 0-5 V range by amplifier A1. Amplifier A2 provides the "tight-lip" response. It has zero output when the sensor output is at midrange, and a dead zone around this operating point is provided by the feedback network. With the component values shown, the dead zone is about 20% of the total range. The gain in the dead zone is non-zero, and the response through this region is quite smooth, due to the characteristics of the diodes.

Amplifier A3 provides the "loose-lip" response. It responds above a threshold force that is near the midpoint of the transducer range so that it does not produce a signal with the normal force needed to seal the mouthpiece against air leakage. An output switch, not shown, selects between the two modes.


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