voltage between the working electrode (WE) and the counter electrode (CE). is the last measured electrochemical potential, i.e. the voltage between the reference electrode and WE to be kept constant. is the next cell voltage to be set, i.e. the controller output. is the setpoint, i.e. the desired . If the measurement intervals of Eq. (8) are kept constant, the control algorithm sets the cell voltage so to keep as close as possible to the setpoint . The algorithm requires software-controllable hardware such as a digital multimeter, a power supply, and a double-pole double-throw relay. The relay is necessary to switch polarity. Significant features In electrochemical experiments the electrodes are the pieces of equipment that comes in immediate contact with the analyte. For this reason the electrodes are very important for determining the experimental result. The electrode surface may or may not catalyze chemical reactions. The size of the electrodes affects the magnitude of the currents passed which can affect signal to noise. But electrodes are not the only limiting factor for electrochemical experiments, the potentiostat also has a limited range of operation. The following are a few significant features that vary between instruments. Electric potential range (measured and applied): while the potential window is mostly based on the solvent window the electronics can also limit the possible range. Accuracy in potential (measured and applied): limits of deviations between the actual and reported. Range of scan rate: how slow or fast a potential window can be scanned. This is most important for experiments that require high scan rates such as those involving ultramicroelectrodes. Sample rate: the rate at which potential or voltage can be accurately sampled. This can be important for experiments that need high scan rates such as those involving ultramicroelectrodes. File size: a limiting factor can be the file size limit. This would most likely affect the choice of the potential range swept or the potential sample rate. Electric current range (measured and applied): the maximum range over which current can be sampled. Applying large currents is important for experiments that pass a great deal of current like a large bulk electrolysis. Measuring small currents is important for experiments that pass small currents like those involving ultramicroelectrodes. Current resolution: determines the operational range of a specific experiment and the bit resolution of that data in the current dimension. Accuracy in current (measured and applied): limits of deviations between