In accordance with an embodiment, a control circuit for controlling a light emitting diode includes a first switching circuit having first and second inputs and an output and a second switching circuit having at least first and second inputs and an output, the first input coupled to the second input of the first switching circuit. The cell also includes an oxidant electrode configured to operate as a cathode to reduce oxygen when connected to the load. The method comprises sensing a power received from an external power source; when the power received is lower than a threshold value, periodically cycling power from a backup power source to one or more lamps; illuminating the one or more lamps; and controlling traffic based on the one or more lamps. Hence, before delivering the product to the purchaser, the settlement is completed, and the credit card number of the purchaser is kept secret from the seller.