Multichannel Systems MPA32I Manual - Manual (Page 11)

FlexMEAs
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6. Connect all unused recording channels to the GND input or to the reference electrode if the
reference and ground electrode of the amplifier are short circuited, to avoid noise pickup. As the
total amplifier gain generally lies in the range of 1000, even very small noise signals may generate
high noise signals.
7. If you are not using a Faraday cage, it might be necessary to shield the complete setup with
aluminum foil or similar to prevent electrical interference from the outside. Connect the
aluminum foil to the ground of the setup (for example, the metal table).
Troubleshooting: If you observe problems with noise, check that the ground of the setup
is connected to exactly the same ground as the data acquisition computer . For example,
connect the metal table to the ground / earth wire of a free power outlet (of the same electrical
system), as the computer is generally connected to ground/earth via the power plug, too.
Also, connect the
data acquisition computer’s metal case with a thick ground wire
to the ground of the setup (for example, the metal table), preferably with a 4 mm plug.
3.2 Testing the Noise Level of the Setup
A terminal plug that connects all inputs to ground, and a test model probe that mimics the
electrode impedance are provided for testing the noise level of the setup. Please note that all
instruments were thoroughly tested at the factory site before delivery. The suggested tests are
mainly intended for optimizing and troubleshooting your setup, to exclude any damage that
might have occurred during transportation, or to fulfill your own guidelines, for instance. It will
take only a few minutes time and can save time and trouble in the long run. Multi Channel
Systems recommends running these tests before you start your real experiments.
1. Connect the terminal plug to one miniature preamplifier and the test model probe to the other
as shown in the picture (do not mismatch the polarity). If you have only one MPA32I, you can
perform the two tests consecutively.
2. Connect the MPA32I with the test model probe to channels 1 to 32 of the signal collector.
3. Connect the MPA32I with terminal plug to channels 33 to 64 of the signal collector.
4. Make sure that all other connections are appropriate, and that your setup has an appropriate
grounding and shielding as recommended in the chapter “General Setup Recommendations”.