Low Impedance Headstages
RA4LI - Four Channel Headstage
The RA4LI headstage is designed for low impedance electrodes with input impedance between
< 1 kOhm and 20 kOhm. Electrode connectors are standard 1.5 mm safety connectors making
it easy to connect to standard needle and surface electrodes for recording evoked potentials
and EEG's. The headstage connects directly to the RA4PA Medusa preampli
fi
er's 25-pin
connector. A built-in impedance checker can be used to test each channel and the reference.
Additional 20x gain on the headstage improves signal-to-noise of low voltage signals.
Impedance Checking with the Low-Impedance Headstage
The Impedance checker on the RA4LI provides a simple check of the channel impedance
relative to ground. To check the impedance level, press the button next to the channel
indicator. The highest-level light indicates the maximum impedance between the channel and
the ground. If all impedance lights are illuminated it is likely that one of the channels is not
properly connected. The (-) impedance button checks the impedance between the reference
(black connector) and the ground (green connector).
Low Impedance Headstages | 4
