Developed for XCEL Power Systems, NHDS recently completed the pre-production development of a particle analyser for measuring ferrous and non-ferrous debris aircraft engine oils. This was an unusual diversion into the complex field of mixed signal electronic design. Very low level analogue signals from transducers are tuned, amplified and measured to produce a meaningful representation of ferrous and non-ferrous particles held in suspension within engine oil, while flowing through a transducer attached to the engine.