Electrolyte solutions of tetrabutylammonium bromide at concentrations from 10^-4 to 4 mol dm^-3 in propylene carbonate acetonitrile mixtures and in the pure solvents, 0 ≤ x_PC ≤ I (x_PC: mole fraction of propylene carbonate), at temperatures -35 ≤ θ /°C ≤ 75 are chosen to exemplify the treatment of electrolyte conductivity as a function of electrolyte concentration, solvent composition and temperature with the help of Hamiltonian models at McMillan-Mayer level. Data analysis is based at low to moderate concentrations on the Chemical Model of electrolyte solutions, at moderate to high concentrations on the Mean Spherical Approximation. Alternatively, the Casteel Amis equation is used to exemplify the reproduction of data for technical use with the help of empirical equations. The measurements on solution conductivity, solution density, solvent viscosity and permittivity were carried out on highly pure products in an inert gas atmosphere with an equipment known to yield precise data.