An alternative to the use of a zero resistance ammeter for electrochemical noise measurement: Theoretical analysis, experimental validation and evaluation of electrode asymmetry

•Potential noise generated by two electrodes coupled by an external resistor is analyzed.•Two values of apparent noise resistance can be obtained.•Electrode asymmetry can be evaluated.•The simplified measurement circuit does not feedback noise to the electrodes.•Results are validated by real-time imaging of the corroding surfaces. The measurement of current and potential noise during corrosion generally requires two electrodes, coupled by a zero resistance ammeter (ZRA), and a reference electrode. Statistical methods then enable estimation of the noise resistance, if the electrodes are identical. In this work, a resistor is used instead of a ZRA and, consequently, the electrodes potentials are partially decoupled. This enables evaluation of electrode asymmetry and the reliability of the estimated noise resistance. Additionally, the simplification of the current-measuring circuit ensures that no instrumental noise due to active electronic components within the ZRA is fed back to the corroding electrodes.