NFAC Transducer Adaptor PCB

NFAC's data acquisition system routes strain-gauge signals through Pacific Instruments amplifier boards that only work when the excitation common sits within a 10V window of both signal legs. A transducer grounded off facility common would violate that requirement and clip the output. Replacing the amplifiers wasn't realistic, as they're decades old and hard to source, so instead the facility team tasked me with designing an adaptor that could fix the signal clipping issue.

I found documentation for this issue in a six-year-old facility worknote and used it to design a small board in KiCad that ties the excitation common to the negative signal leg to trivially fulfill the 10V condition. The work happened on airgapped machines with no internet access, so every footprint and 3D model was built by hand from datasheets and drawings. 

Each adaptor recovers roughly two channels per amplifier board, against several hundred boards across the facility DAQ. As of writing this, they haven't shipped in quantity yet, so the real validation is still ahead.