eDAQ e-corder, Manual

Page: 31 / 112

Chapter 3 — The Dual Picostat 27
In all cases, it is essential that the Faraday cage be electrically
grounded to act as an effective shield against electrical interference.
The case of the Dual Picostat is grounded via its connection to the
e-corder
unit which is in turn earthed via the three pin mains power
connector. It is of course important that the power socket that you are
using is well earthed. The purpose of this ground cable to the Faraday
cage is to provide an easy means of grounding the cage — please
note that it is not for grounding the Dual Picostat.
If your Faraday cage is already earthed by its own ground connection
then you should not use the ground cable to the Dual Picostat! Use of
the cable in this instance will provide a second pathway to earth which
could result in a ground loop which can actually increase signal
interference! Thus you can try grounding the Faraday cage via its own
connection to earth,
or via the Dual Picostat ground cable — but not by
both methods simultaneously.
Connecting the Dual Picostat
The Dual Picostat will have been supplied with an I
2
C cable (DB–9 pin
connectors at either end), and two cables each with three BNC
connectors at either end.
First make sure that the
e-corder
is turned off. Then connect the I
2
C
cable to the I
2
C connector on the back panel of the e-corder , and the
other the other end to the I
2
C Input connector on the back panel of the
Dual Picostat. Use the BNC cables to connect the back panel of the
Dual Picostat to the front panel of the
e-corder
as in Table 3–2 .
With these connections, when you use the software to set a more
positive voltage at ‘E in’, a more oxidising (anodic) potential will be
applied at the working electrode. Such an arrangement is shown in
Figure 3–5 and Figure 3–6 .
To operate the Dual Picostat with the reverse polarity change the
connection at e-corder to e-corder Output –. Now when you
set a more positive voltage in the software, a more negative potential is
sent to E in, and a more reducing (cathodic) potential will be applied at
the working electrode.