Experiments have been carried out with a ring array of iron electrodes in sulfuric acid under conditions in which high-frequency periodic and chaotic oscillations occur. All the electrodes were held at the same constant potential. The currents of the electrodes were measured independently, and therefore, the spatiotemporal patterns in current density which occurred were directly determined. Depending on the conditions of the experiments, primarily applied potential, and also solution concentration, a variety of periodic and chaotic oscillatory spatiotemporal patterns arose. The simplest case, a uniform periodic oscillation, does occur, but it is not the most common state. With a change of parameter, higher modes become important. One set of changes among pattern types with variation of potential, including an apparent period doubling, is investigated in detail. Other types of behavior including antiphase oscillations and chaotic patterns were also observed.