Chapter 3: Measurement of Small Current Signals
13
as “Code 2” in the Data View. Below is a table of time constants associated with each range where the
TC>500ms.
Table 2. Time Constants
Current Range
Time Constant
20nA
900ms
2nA
2.1s
200pA
5s
20pA
7s
4pA
7s
3.4.2. LCI Bandwidth Limits
All potentiostats can become unstable and oscillate when connected to capacitive cells. Although
designed to minimize the onset of these oscillations, they can still occur in some experimental conditions,
and are most often manifested as excessive noise or “jumps” in the data and graphical output.
If an oscillation is suspected, one can use the LCI Bandwidth Limits in the VersaStudio software to try
and eliminate the oscillation. The “limits” are a range of damping filters (Normal, Slow, and Very Slow)
within the control loop of the VersaSTAT LC Low Current Interface that can help prevent oscillations
when performing experiments on capacitive cells. There is no recommended setting other than Auto
(which is “Normal”), and if oscillations occur, try stepping to “Slow” first, then “Very Slow” as a last resort.