The equivalent circuit method is extended to the case where two layers of the ionosphere, e.g., E and F regions, are treated as separate connected circuits. In this way the driving of E region currents by F region emf's can be studied. The net effect of the two layer current systems is similar to previous calculations, but some insight into current profiles is provided. It is seen that these may affect f0E variations. The dependence of electrostatic field strength on sunspot number is studied. Variations of the sunset increase in field are suggested to be mainly due to phase changes in the driving winds.