eDAQ Picostat, User Manual

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Chapter 2 — The Potentiostat 17
You can shift or stretch the vertical Amplitude axis to make the best use
of the available display area — similar to the amplitude axis in the
main Chart, Scope or EChem window.
Setting the Range
Use the Range pop-up menu to select the input current range (channel
sensitivity). The Potentiostat has ranges of 100 mA to 2 nA, while
resolution within each range is 16 bits or 0.0015%. You should set the
range so that it is larger than the biggest current that you expect to
encounter during your experiment. If, during the experiment the current
signal exceeds the range, then the signal will go off scale and be lost.
Filtering
The Potentiostat incorporates four low-pass filters at 10 kHz, 1 kHz,
100 Hz and 10 Hz for removal of high frequency signals (‘noise’).
In addition the e-corder provides filter settings at 1, 2, 5, 20, 50, 200,
500, and 2000 Hz (Chart software on Windows computers).
As a general rule the 10 Hz filter setting is highly effective for the
removal of mains hum (50 or 60 Hz interference) and should be
employed whenever possible. However, it should not be used for
pulsed amperometric, or voltammetric experiments, where the pulses
are shorter than 100 ms, or for experiments where rapid scan rates
(greater than about 100 mV/s) are used.
With Chart and Scope software, there is an additional Mains Filter
checkbox,
. If this is ticked, then the e-corder will apply a
mains filtering algorithm to the incoming signal which removes
repetitive signals occurring at 50 or 60 Hz which are typical of mains
interference. Note that the mains filter is not a notch filter, and that it
can remove a 50 or 60 Hz interference even if it is not a pure
sinusoidal function. However, the mains filter does take a few seconds
to ‘learn’ the pattern of the interference so that you will need to record
for longer than this for it to take full effect. The mains filter can be
employed even for experiments in which there are sudden potential
jumps.