Modifications have been made to the AutoAC to dramatically reduce noise in AC impedance curves. Systems using remote reference electrodes salt bridges and lugin probes are prone to very high levels of mains pick up causing large random scatter of data points. A well-established technique to remove this noise is to provide an AC coupled feedback path from the reference electrode output back to the electrolyte. This is typically an additional platinum electrode coupled to the RE by way of a 1microFarad capacitor. This capacitor has been built into the AutoAC for convenience. The connection to this noise reducing electrode is made using the second connector on the RE lead marked NR (for noise reduction).

In practice this NR electrode does not have to be platinum (although conventionally it is) our experiments have shown that for example another working electrode can be used. This does not change the rest potential as the NR electrode is purely AC coupled with no DC component.

For example the bode plot showing phase v frequency below shows the result using a SCE and lugin only in green and in red the SCE lugin and a Pt electrode connected to NR. The data is much cleaner and no other parameter of the cell is changed.

All run parameters were the same.

In many cases the Noise Reducing electrode will not be needed but if the data looks like the green curve above it is strongly recommended.

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