•Non-destructive evaluation techniques in measurement applications require transferring complex signals to usable quantities.•Equivalent circuit models for eddy current sensors evaluated for their voltage transfer functions are those of lossy transformers.•Splitting transformer coupling and eddy-current losses enables simple models, which can be automatically constructed.•Implementation of parameter identification in a real-time soft sensor is possible.•This soft sensor can be used to measure material properties in a repeatable fashion. The use of eddy-current techniques as a measurement method for material characterization instead of simple fault detection requires transformation of the electrical response signals to quantifiable physical parameters that correlate with material properties. Apart from calibration-curve methods, exact approaches that correctly represent all interactions between excitation field and response field are computationally intensive and not well suited to real-time application. In this work, an equivalent circuit network model is constructed and its analytical equation for the voltage transfer function is derived. This model is then implemented in a soft sensor system. Finally, measurement results from various materials with different electromagnetic properties are presented.