Considerations of Potentiostatic Control

The time base of available storage oscilloscopes limits low-frequency measurements to about 10 Hz. High-frequency limitations are imposed by effects external to the oscilloscope, principally stray capacitance and transmission line effects in the leads and cell. Measurements can often be made at frequencies above 10 Hz. 

The primary limitation of this technique is precision. Oscilloscope linearity is seldom better than 1%, and it is difficult to measure phase angles directly with a precision of better than 2°. Measuranents usually can be accomplished with an uncertainty in Z and Z of 3% of Z.  

A single-beam oscilloscope or an Z-F recorder also can be used to measure impedance parameters directly by the method of Lissajous figures. 

Limitations of oscilloscopic recording are essentially those of precision as described above for two-channel measurement. However, since time is not an explicit variable, time base limitations do not apply when recording Lissajous 

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