Miniature rotating amplifier system for windtunnel application packs 256 pre-conditioning channels in 187 cubic inch

For a NASA windtunnel model NLR developed a 256 channel pressure sensor signal conditioning and amplifier system. This system was to be mounted within the rotating part of the model in a volume of 7 inch diameter and less than 6 inch long. The development of this system, called Rotating Amplifier System (RAS), required a close cooperation between electrical and mechanical designers to meet all customer requirements. For all 256 channels the bridge supply voltage, offset and gain are separately remote controllable to allow for adjustments during a running experiment. These configuration settings are loaded into the system using a dedicated serial link. For on-line calibration an R-Cal function is available with 3 separate resistor values. The mechanical construction of the RAS unit consists of a cylindrical unit that is mounted on the propeller shaft between gearbox and sliprings. The RAS unit is of modular design and consists 16 of identical modules, each containing 16 self contained amplifier channels, sensor power supplies and associated control logic. The amplifier system was realized using specially developed hybrid modules and packs the complete functionality in 187 cubic inch