ZView has three discrete Circuit Modeling methods; Simulating Data, Fitting Data and Instant Fit. When simulating, the user provides values for each component (R, C, etc) in the model and ZView calculates the impedance spectrum of that model. When fitting, ZView alters the values of the components and attempts to find the values which best fit your data. Instant Fit is a special technique where a small portion of data is fit to a simplified model. The results are then used as starting values for the full circuit model.
Simulating is particularly useful when first using a new model. Often the relationship between the component values and the spectrum is not intuitive. Changes in the component values may change the spectrum in unexpected ways. By simulating the spectrum with a variety of component values, you can get a 'feel' for the model.
Select Tools | Equivalent Circuits... (or click on the icon). ZView starts with a blank model to which elements are added. A number of predefined models are available. We will initially use these, and later build one ourselves. The predefined models are described in Appendix C of this manual.