Digitimer NeuroLog NL824 Benutzerhandbuch - Seite 3

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Users Manual
Connection
Fig. NL822-1 illustrates the output and supply connections provided via the 9-way plug to a matching socket.
Normally when used with the NL820A ISOLATOR module the correct connections are made by inserting the
plug into the socket.
The NL824 provides channels through to outputs 1-4 on the NL820A.
The NL822 connects channels 1 and 2 to outputs 1-2. A "T" adaptor (Part No. NL969T) is available for
connecting two NL822 amplifiers to a single NL820A to drive outputs 1-4.
The information provided on Fig. NL822-1 will therefore only be required if an NL822 or NL824 is to be used
without the NL820A in which case one, or more, matching socket(s) must be ordered (Part No. NL969S).
Pin No.
Function
1
Channel 1
2
Channel 2
3
Common
4
+13V
5
-13V
6
Common
7
Channel 3
8
Channel 4
9
Mute
Operation
The NL822 and NL824 amplifiers are suitable for amplifying low level AC signals in the presence of large
interference potentials from mains supply sources and DC potentials generated by electro-chemical action at
electrode interface connections. They are particularly suitable for electro-physiological measurements, however
it is still important that care is taken over input connections and wiring layout.
When recording differentially, electrode leads should be run close together and where possible twisted.
Connection impedances should be as low as possible since although the amplifiers present a high input
impedance, both noise and common mode rejection of power source interference will deteriorate with increased
signal source impedance.
Similarly although the amplifiers are AC coupled there is a limit to the magnitude of any DC potential which can
be applied to the input terminals without producing limiting effects on the signal. Accordingly good quality
matched electrodes should be used to minimise these potentials.
Switch setting of gain and low frequency cut-off point are clearly marked on the front panel and can be adjusted
by the user as required to suit the application. The sensitivity of any channel can easily be checked by
connecting either input socket to the 100 microvolt calibrate socket whilst linking the un-used input socket to
common.
When used with the NL820A ISOLATOR module the amplifier inputs are separated from ground by the isolation
barrier existing within the NL820A. It is therefore important if this safety feature is to be preserved that
accidental grounding of the input circuit is avoided.
The mute push button on the front panel provides for rapid resetting of the amplifier coupling components to
minimise blocking effects following large "artefact" signals. It can also be operated immediately prior to any
expected disturbance or external stimulus and will suppress the output whilst the button is held depressed.
Digitimer Ltd
NeuroLog™ System
Page 3 of 4
Tel:+44 (0)1707 328347; Fax:...373153
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7
2
9
3
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Fig. NL822-1
Website: www.digitimer.com
NL822/824
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