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
NL506 – Analog Switch
The NL506 contains a single pole change-over analog 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 analog, it can handle signals up to +15V as well as being of low enough impedance to handle TTL signals.
NL703 – EMG Integrator
The NL703EMGIntegrator module was designed to produce an analog signal to represent the amount, or strength of muscle activity. The unit will accept signals up to +1V which are full wave rectified and applied to a “leaky integrator”. 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.
