A fourth simulation product SimOhm is now available. SimOhm allows modeling and simulation of circuits such as the Wheatstone bridge shown below.
Currently, SimOhm support resistors and cells. Linear as well as parallel circuits can be modeled and simulated. Sliders are provided to vary resistances and cell voltages. To simulate, simply click on the play icon. Then click on the probe icon to the left of the play icon and move the mouse pointer over various circuit elements to view currents, voltages etc. throughout the circuit. The model shown above can be accessed by clicking here.