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1.
How
do I correctly set the values on the NL403 Delay/Width module?
The
NL403 has both a Range Control and Variable Control which allows
precise setting of the values of Delay and Width. Click
here to view a PDF file which explains how to use these
setting controls.
2.
I'm
using the NeuroLog system to record extracellular potentials.
How do I use the NL120S Audio Amplifier to monitor spikes audibly?
Can I use the "Mon" output of the NL201 Spike Trigger?
It
is easy to do this, but you MUST NOT use the "Mon"
output of the NL201 as this would generate an unpleasant
"ringing" noise. The Monitor output is intended to
provide an oscilloscope display of the input signal with the upper
and lower window levels superimposed.
To listen to the spiking, you should actually take the raw or
filtered output from your NL104A AC preamplifier or NL106 AC/DC
Amplifier and feed this into (i) your data acquisition system and
(ii) the input of the NL120S using an NL961 "T"
connector and a couple of cables. The threshold of the
NL120S can then be adjusted and the output listened to using the
NL985 Speaker connected to the Audio Amplifier.
3.
I
see that the NeuroLog Case is now called the NL900D - why
has it changed and is it compatible with older NeuroLog modules?
The
NL900C has now been superceded by the NL900D, which was introduced
due to discontinuance of certain components. The new case
system is fully backwards compatible with older NeuroLog modules.
4.
I
want to feed my output signal from the NeuroLog system into a data
acquisition board fitted with BNC sockets, what is the easiest way
to do this?
The
NeuroLog system uses micro-miniature Lemo coaxial cables, plugs
and sockets, while many other devices use more common BNC
connectors. We supply single pole Lemo cables of various
lengths (NL951)
with a Lemo plug at both ends, however you can purchase an NL960
adaptor from us which fits one of the Lemo plugs and turns it into
a BNC plug. As an alternative, we can offer 1m and 2m cables
with Lemo plugs on one end and BNC plugs on the other (NL951B-1m
or NL951B-2m).
5.
I am using more than one NL100AK headstage in order to make
extracellular recordings, however I seem to be picking up a large
amount of noise. When I use each headstage on its own, the
problem goes away. What is happening?
When
using multiple NL100AK headstages it is important to ensure that
you maintain a single grounding point when wiring up the
headstages, as you may be setting up ground loops. In order
to avoid ground loops, please follow this
Application Note.
6.
I am using the NL100AK headstage and NL104A AC Preamplifier to
record extracellular spike potentials, however I find that my
signal is intermittently lost for a few seconds. This loss
of signal seems to occur shortly after electrical stimulation of
the tissue. If
your signal appears to be fine most of the time and you only see
this loss of response at the point of stimulation, then I would
check the setting of the low frequency cut-off filter on the
NL104A front panel. In order to produce a flat baseline, the
NL104A uses this low frequency cut-off filter to remove unwanted
DC potentials from the signal. The switch can be set to
0.1Hz or 10Hz. At 0.1Hz the amplifier will not filter out
your stimulus artefact and as a result, the large DC offset will
temporarily prevent the amplifier from working correctly. If
you change the setting to 10Hz, you should solve your problem.
7.
I am intending to use the NL107 Transducer Amplifier to make field
potential recordings from brain slices, can you tell me how the
amplifier should be configured? Extending what the
NL107 Users Manual says. The
amplifier differentially amplifies the signal between the A-in and B-in
("A-B") thereby removing any Common-Mode interference that is present on both
inputs. Connections MUST be made to both inputs and if the preparation is
grounded/earthed it is preferable to perform this using the Ground from
the NL107 input - the shell or braid. If full differential recordings are not
required, it is best if the "B-in" is connected to the point that is grounded actually
AT the preparation. The Balance control sums a DC potential with the input signal. The control
can be locked using the small side lever. Note that the AC/DC switch on the unit must be set to "DC" to record
same.
8.
Is it possible to use a trigger input to gate the NL512 Biphasic
Buffer, thereby controlling stimulus timing and pulse duration,
and a computer DAC to separately control the NL512 output
amplitude?
Yes,
the NL512 has two inputs (GATE & IN). An incoming
trigger pulse at GATE can be used to gate the voltage applied at
IN. As a result, even with a voltage applied at IN, there
will be no output from the NL512 until the GATE input is made high
by the trigger pulse.
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