The left switches control which adapter is used to power the charger board (DC center pin positive, DC Center pin negative, and AC). The upper switch controls the charge rate for NiCad or NiMH batteries. The right switch is used to set up an initial voltage for the capacitor (modeling a 6 AA rechargable battery pack), so that the simulator can find a solution (Below 8.5 volts will cause the charger to charge the batteries. Above 8.5 volts will cause the charger to discharge the batteries. The 720 mOhm resistor models the internal resistance of the battery pack.
http://eecs.oregonstate.edu/education/docs/chargerboard/schematic.pdf
