An open-source potentiostat/galvanostat instrument design is introduced that provides the ability to take accurate measurements over a current range of ±200 mA and a potential range of ±12 V. The improved capability of the instrument compared to the previously published design upon which it is based makes it suitable for performing a wider range of electrochemical measurements including the ability to use larger working electrodes, study of high current density processes, study of electrochemistry in nonaqueous solutions and use in high voltage processes such as electrophoretic deposition. The instrument can be controlled from any computer capable of running the Python programming language, including a low-cost Raspberry Pi. Unlike many commercial potentiostat designs, the instrument is completely open-source, giving researchers the ability to modify the hardware and software as needed for custom measurement techniques. The low cost makes the instrument attractive for research and teaching laboratories in which multiple electrochemical measurements need to be carried out in parallel.