iWorX ETH-256 Hardware Manual
ETH-256 Amplifier with Isolated Headstage
Hardware
Manual
ETH-256
ETH-256C
iWorx Systems, Inc.
www.iworx.com
LabScribe is a trademark of
iWorx Systems, Inc.
©2015 iWorx Systems, Inc.
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Overview
The ETH-256 is a high performance general-purpose life science research
amplifier. Its high input impedance and high Common Mode Rejection allows low
noise recording of biopotential signals, as well as outputs from strain gauge type
transducers, including force, displacement, and pressure transducers. The ETH256C includes the C-ISO-256 isolated headstage for recording ECG, EMG, and
EEG signals from humans.
The ETH-256 offers eight gain settings: x1, x5, x10, x50, x100, x500, x1k, and x5k.
Signals may be further conditioned using high- and low-pass frequency filters. All
ETH-256 Amplifier with Isolated Headstage
filters are four-pole active design with sharp roll-offs. High-pass filter cuts, useful
for biopotential measurements, are available at DC, 0.03 Hz, 0.3 Hz, and 3 Hz.
Low-pass filters, for limiting high frequency noise, are available at 5 Hz, 50 Hz, 150
Hz, 2k Hz, and 10k Hz.
Either of the ETH-256 amplifier's channels may be configured as a bridge-style
transducer amplifier or as a biopotential amplifier. In Bridge mode the ETH-256
amplifier's 10 gigohm input impedance and differential input allow it to accept input
from force, displacement, or pressure transducers. In addition, input from many
thermistors, pH electrodes, and other variable resistance devices is possible. In the
Biopotential mode, the ETH-256 functions as a low noise AC-coupled preamplifier.
Included Items
ETH-256 Two-channel Combination Bridge/ECG/EMG/EEG Amplifier
ETH-256C includes an Isolated Headstage (C-ISO-256)
Two10 ft. BNC-BNC cables (C-BNC)
Two-conductor 12 VAC power supply with a 3.5mm output plug (A-P12-AC-3.5)
Package of 50 disposable electrodes (A-GC-7165)
iWorx Systems, Inc.
www.iworx.com
Front Panel
The ETH-256 is divided into two units or channels with identical functions that are
capable of making low noise, AC-coupled recordings of bioelectric potentials, or
DC-coupled transducer recordings.
Each channel can provide ±5.0V of excitation at 50 mA, adequate for most
commonly used transducers. In addition, customers may specify adapter cables to
accommodate Grass, Gould, or HP sensors.
High-Pass Filter [HPF(Hz)]
The high-pass filter has four positions. Each time the button is pushed, the filter
advances, in step-wise fashion, to the next filter as indicated by the LEDs. The DC
position directly couples the input to the amplifier and is used for measuring from
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wheatstone bridge-style transducers or other ground-referenced sensors requiring
impedance conversion, such as pH electrodes or ion-selective electrodes (ISEs).
ETH-256 Amplifier with Isolated Headstage
There are three AC-coupled, high-pass filter settings: 0.03, 0.3, and 3 Hz. For
ECG, EEG, and EOG recordings, 0.3 Hz is normally used; for EMGs, 3 Hz is
commonly used. The result of using a high-pass filter with a higher value is the
creation of a more stable recording baseline; contributions from body movement or
breathing can be removed with high-pass filter settings.
Low-Pass Filter [LPF(Hz)]
The low-pass filter control sets the upper limit of frequencies measurable by the
ETH-256. The setting labeled 10k offers a maximum frequency response of about
10k Hz. Other settings may be chosen to limit noise. For example, the 50 Hz filter
removes signals above 50 Hz. AC noise at 60 Hz, the most common source of
electrical interference, would be filtered from the recording along with any other
frequencies above 50 Hz. For very slow (low frequency) signals, such as the
output of a force or pressure transducer, the 5 Hz setting will provide the quietest
recording.
Gain
The gain of each channel on the ETH-256 can be adjusted independently. This
allows very small signals to be amplified before presentation to the display device.
The gain control push-button allows you to select among eight preset multipliers:
x1, x5, x10, x50, x100, x500, x1k, and x5k.
iWorx Systems, Inc.
www.iworx.com
Input Offset
The position of the recording baseline, in either Bridge (DC) or Bio (0.03, 0.3 and 3
Hz) mode, can be moved up or down by using the Input Offset knob. This control is
very important in Bridge mode where the output of a transducer may need to be
zeroed, or the maximum height of the recording display area may need to be set.
Input
The input connectors are either BNC connectors for single-ended devices, or DIN8
connectors for transducers, isolation pods, headstages, and current-to-voltage
adapters.
Rear Panel
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