The 2mF capacitor simulates the battery, and the switch near the top above it simulates plugging and unplugging the battery from between the charger and an intended use, in this case it is setup to light a terquoise L.E.D. The 5v power source simulates the USB port, and the switch below it, near the ground, simulates plugging and unpluggin the charger from the computer USB port. Starting state is the battery is plugged into the charger, and you then must plug the charger into the computer by using the right-most switch. The red L.E.D. stays lit until it is fully charged. When cahrged, using the left-most switch, simulates unplugging the battery from the charger and plugging it into your L.E.D light application! - nforystek
