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These
modules provide the basic pulse generation mechanism within a
NeuroLog System. When appropriately used, the NL301 Pulse
Generator and NL304 Period Generator can initiate repetitive
pulses/periods which can be used to synchronize external devices
(as a TTL trigger source) or form the basis of more complex stimulation protocols. The
NL412 is a simple handheld trigger box which can be used to start
or gate a protocol and is also used as a remote "buzz
box", useful when making intracellular recordings with the
NL102G DC Preamplifier.
NL301
- Pulse Generator |
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The
NL301 is a low cost module for producing trains of uniform
TTL pulses. It can be operated continuously, switched off,
or a single pulse can be triggered manually. A
"gate" input socket is provided to allow
synchronous trains of pulses to be gated-on by an
externally applied TTL signal. Pulse
frequency is continuously variable over more than three
decades and three fixed output pulse widths are
available. The frequency range and pulse widths were
chosen to make this module suitable as a timing source for
electrical stimulation of the nervous system, without the
necessity of additional modules for determining the pulse
width. The NL301
is also useful for a variety of other timing purposes
where a widely variable rate is desirable, and precision
is important but not critical.
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NL304
- Period Generator |
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The
NL304 contains a crystal oscillator and frequency dividers
for producing a precise, stable frequency standard. It can
be externally gated (GATE IN) and synchronised with
an external source (RESET input). The pulse train can be
switched off and a single output pulse can be produced
manually by a front panel push switch.
The
NL304 is the basic "clock" of the NeuroLog
System as it provides the "fine grain" (1 microsecond
increments) necessary for digital control of pulse width,
cycle duration, delay, etc using the NL603 counters.
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NL412
- Pulse |
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The
NL412 is a small, handheld, general purpose
pulse generator which can be used to "start"
experiments, command the
"gate" of a train of pulses or be
used with an NL102G
DC Preamplifier to "Buzz" electrodes.
The NL412 is self-powered by a
standard internal 9 V battery
and is fitted with a 2 m lead terminating in the standard
Lemo connector. It is now supplied with all new NL102G
amplifiers.
Start
- On pressing the button the
NL412 generates an active high
pulse which will trigger remote modules. Gating
- The front panel control on
the NL412 provides control for output
pulse durations over the range of 1 to 10 ms.
Setting this control allows different durations of trains
of pulses when the
NL412 is combined with a the NL301
Pulse Generator (see
above). Use
with NL102G - When
used with a NL102G (that incorporates external "Buzz"
control circuitry) the duration of the "Buzz" is
set by the front panel
control.
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