eDAQ Picostat, User Manual

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Chapter 3 — The Picostat 37
Filtering
The Picostat has an internal 10 Hz low-pass filter for removal of high
frequency signals (‘noise’). The Off setting gives the full bandwidth of
the Picostat which can be up to 16 kHz (but which may also be limited
by the characteristics of your electrodes and sample solution).
The 10 Hz filter setting is highly effective for the removal of mains hum
(50 or 60 Hz interference) and, as a general rule, should be employed
whenever possible. However, it should not be used for either pulse
amperometric or voltammetric experiments where the pulses are shorter
than 100 ms, or for voltammetric experiments where fast scan rates
(greater than 100 mV/s) are used, or for other signals which are likely
to exhibit fast rise or fall times — otherwise excessive smoothing of the
signal may occur.
In addition, with Chart and Scope software, there is a 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 can remove 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.
Inverting the Signal
The Invert checkbox allows you to invert the incoming current signal. It
provides a simple way to redefine the directions (up or down) of an
anodic (or cathodic) current signal. This control
does not affect the
direction of current flow at the electrodes.
Cell Control
The Picostat can be in one of two operating modes, controlled by the
Cell radio buttons:
• Standby : If Standby mode is selected the auxiliary and reference
electrodes are isolated by an internal relay which effectively means
that all the electrodes are at a ‘floating’ potential and that no current