Testing the EPC9 EPC9 Manual 30
The action of the internal filters on the background noise level and the temporal
response can be observed by changing Filter 1 and Filter 2. An improved signal-to-
noise ratio should be apparent when the Gain is increased to 50 mV/pA or greater
(which selects the 50 GΩ measuring resistor).
With filter 2 set to 2.9 kHz (4) and nothing attached to the probe you should read a
noise value between 90 and 110 fA (2).
Tip: If you wish to ground your setup you should now attach the pipette holder to the
probe, insert a glass pipette, bring the pipette tip into the recording position near the
recording chamber and power on every piece of equipment that introduces noise
(lamps, oscilloscope, camera, ...). Setting the duration of the test pulse to 100 ms (5)
and the gain of the E9SCREEN oscilloscope to a high value (6) will make the noise
and the 50/60 Hz pickup very obvious. In a well grounded setup all these
components should introduce no more than about 100 fA of additional noise.
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