NL202 - AC Signal Delay

The NL202 AC Signal Delay is an analog signal delay unit utilizing a 'bucket-brigade' delay line, providing a low cost unit and almost continuous representation of the delayed signal.  However, the NL202 cannot produce delays of more than 50msec, nor can it be used for very low frequency (DC to 5Hz) signals.  The NL202 is ideal for use with the NL201SpikeTrigger for visualizing the entire waveforms of amplitude - discriminated spikes or for producing pre-triggered averages of AC signals (consistent with its limited delay range).

  NO LONGER  AVAILABLE

NEW  NL254 - Ratemeter

The NL254 calculates, using digital circuitry, the 'instantaneous frequency' of each interval in trains of events, uses a 3 digit display to show the rate in pulses per second or pulses per minute and produces an analogue voltage which is proportional to this rate.  It features an adjustable threshold so that additional modules for detecting peaks (such as the NL201 Spike Trigger) should not be necessary.  The NL254 Ratemeter has four ranges which allow it to be configured for low frequency events such as heart or respiration rate as well as higher frequency signals such as neuronal action potential firing.  The NL254 combines and replaces the functions of the NL253 and NL256 which are no longer available

NL410 - Calibrator

This module can be used for the precise calibration of the gain of an amplifier system for adding a pulse of accurate amplitude and duration to a recording trace. The output of the Calibrator is isolated allowing for the user to choose the best method of preparation grounding to optimise recordings. Switches allow selection of 1 of 3 calibrated output levels with 1 of 2 calibrated triggered pulse widths of either polarity. The calibration level at the preset amplitude and polarity may also be enabled or pulsed manually from a front panel switch.

NL506 - Analogue Switch

The NL506 contains a single pole change-over analogue switch. The state of which is controlled by a logic signal. This signal can be generated externally or by the internal Flip-Flop that can be toggled by the negative going edge of a logic input. A front panel switch allows direct selection of the switch state which is indicated by an LED.

The switch is bi-directional allowing it to be used as a 1-input, 2-output or a 2-input, 1-output device. Also, as the switch is analogue, it can handle signals up to +15V as well as being of low enough impedance to handle TTL signals.

NL700 - Log Display

The NL700 converts intervals between input pulses into output voltage levels which are proportional to log frequency.

The S&H output can be plotted directly on a chart recorder for low input rates, and for high firing rates in which the interval structure shows high serial correlation (that is, the interval duration changes only slightly, on average, from one interval to the next. Examples of suitable firing patterns are those of muscle spindles, retinal ganglion cells, central respiratory neurones, motoneurones, etc.

NL701 - Lin Display

The NL701 Linear Display converts intervals between input pulses into ramps whose heights are directly proportional to the interval duration. The peak of each ramp is sampled and this peak amplitude is maintained by a "sample and hold" circuit until the arrival of the next input pulse. The sample and hold output is a continuous signal linearly proportional to the time interval between the previous two input pulses. This output can be used to drive a chart recorder allowing firing interval to be represented on a low frequency output device.

NL703 - EMG Integrator

The NL703 EMG Integrator module was designed to produce an analogue signal to represent the amount, or strength of muscle activity. The unit accepts signals up to +1V, which are first full wave rectified and then applied to a "leaky integrator" within the module. The output of the integrator is buffered and the overall gain is set at unity. The time constant of the integrator is selected by a 6 position rotary switch. A toggle switch is also provided so that the direct signal can be viewed.

NL741 - Analogue Delay

The NL741 Analog Delay module is an analogue delay line consisting of an analogue-to-digital converter (ADC), digital memory, clock logic and a digital-to-analog converter (DAC) at the output. The input signal appears at the output after a fixed delay which is set by the two front panel rotary switches giving an overall delay range of 0.1milliseconds to 2 seconds.

Fast sample rates (200kHz) ensure a 20kHz frequency response for delays up to 20milliseconds, with corresponding frequency response reduction for longer delays (approximately-sample rate/10).

The NL741 can also be used to display the entire waveform of a pulse transient which has been selected by amplitude discrimination (most of the waveform will already have occurred by the time the discrimination is completed) using the NL201 Spike Trigger.

NO LONGER AVAILABLE