UFi 2122 User manual

MODEL 2122 / 2122i
BIOAMPLIFIER
UFI
545 Main Street, Suite C-2
Morro Bay, CA 93442
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Introduction
The Model 2122 is a differential amplifier for use with low-
level signals -- 2 microvolts and above -- ranging from DC
to 10 KHz. Primarily designed as biological
instrumentation, the Model 2122 is well suited to many
other demanding applications. It features high common-
mode rejection, high input impedance, low noise, small
size, and excellent frequency response. The Model 2122i
includes subject isolation, but is otherwise identical to the
standard Model 2122. A BioAmplifier Input Box with
convenient binding post terminals is an included accessory.
Controls and connectors

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Power switch
•Connects power supply to BioAmplifier; should be
left in OFF position when instrument is not in use.
Amplification switch
•Provides 16 fixed-gain settings; Model 2122
frequency response does not change with gain.
High- and low-frequency rolloff switches
•Use these controls to filter out undesirable or
interfering signals. Here are recommended
settings for various bioelectric signals:
•
0.05 Hz and 0.1 Hz settings have long time
constants; Model 2122 may require 30 seconds to
stabilize when first turned on with these settings.
Calibrate µV switches
•Active circuit generates symmetrical square
waves at about 0.5 Hz, and may be used to
test amplifier at any time.
Desired signal Low freq
(Hz) High freq (Hz)
EKG 0.1 50
EEG 1.0 50
EMG 10 1000
EOG 0.05 50
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•Press 500 µV switch to disconnect signal and feed
500 µV calibration to Model 2122 input.
•Press 50 µV switch to disconnect signal and feed
50 µV calibration signal to input.
•Calibrator voltage is usually accurate to 5%.
•Bioamplifier may require rebalancing when
calibrating.
Balance adjust control and meter
•Since the Model 2122 responds to frequencies as
low as DC (0 Hz), you’ll need to adjust this control
when a signal has a DC (offset) component.
•Connect transducer, set amplification to 100.
•Adjust 10-turn balance control in direction you
meter needle to move: clockwise for higher
reading, counter-clockwise for lower.
•Balance control can compensate for some offset
due to electrode polarization potentials: 100-150
mV offset for gains of 200-1000; 10-15 mV offset
for gains of 2000 to 10,000.
•If meter cannot be centered with balance control,
input offset is excessive.
•To check for this, press 500 µV calibrator switch
and adjust balance control. Meter needle should
return to zero and fluctuate with calibrator pulses.
•If this is not possible, a) reduce amplification to
x1000 or less; b) switch to AC position on Model
2122 Input Box; c) use better Ag/AgCl electrodes
such as UFI Model 1081.

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•To input a single-ended signal into Model 2122,
ground unused differential Model 2122 input, then
adjust balance control.
Power connector
• Model 2122 operates from 12VDC wall-mount
power supply plugged into 110VAC mains.
• Use only UFI-supplied wall-mount supply – others
may have reversed-polarity connectors.
Input connector
• Model 2122 features a 6-pin input connector
(viewed from rear, below); pin functions are:
•Energize high-resistance strain gauges (like UFI
Models 1030 and 1040) or similar full-bridge
transducers with the +9V pin. A 0K resistor limits
Pin B current to less than 0.7 mA.
•Driven Shield (Pin F) supplies buffered sum of
inputs from Pins A and E; connect F to transducer
shield for signal with large common-mode
component.
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BioAmplifier Input Box
•Plugs into Model 2122 input connector
•Connects wire-terminated transducers.
•AC switch position blocks DC component.
Rear-panel outputs
•1000-ohm output impedance allows Model 2122 to
drive oscilloscope or virtually any recorder.
•Use DC output for signals that require DC
response like those from Models 1030/1040.
•Use AC output for bioelectrical signals such as
ECG, EEG and EMG.
•Both outputs operate at all times: you can
simultaneously record large-signal DC response
and small superimposed "AC" variations.
•Both DC and AC outputs respond to amplification
and high-frequency rolloff switches.
•Only AC output responds to low-frequency rolloff
switch; it does not affect DC output.
Model 2122 specifications
•Input impedance 10 megohms
•Input connector Switchcraft EN3P6F;
fits EN3C6M plug
•Freq response DC to 10kHz +/- 3 dB
•Frequency rolloff -12 dB/octave
•Common mode rejection 90 dB minimum

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•Noise Less than 2 µV peak-
to-peak, DC to 100 Hz
with 10KΩsource
•Output configuration Single-ended
•Output impedance 1000 ohms
•Power supply 110 VAC-to-12 VDC
wall-mount transformer
•Power input jack Switchcraft 722A;
matches plug S-760
Model 2122i additional specifications
•Maximum isolation voltage 700 volts AC
•Typical leakage current <5 µA at 240 VAC
Warranty and repair
All UFI instruments are warranted against defects in materials and
workmanship to the original purchaser for a period of one year
from the date of original purchase. This warranty is void if our
inspection shows the equipment has been tampered with; or
installed at variance with factory-designated procedures; or has
been subjected to negligence, misuse, or accident beyond normal
usage; or has had the serial number altered, defaced, or removed.
No third party, including any dealer or agent, is authorized
to assume any liability for UFI.
All questions regarding the warranty should be directed to:
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Customer Service Department, UFI
545 Main Street, Suite C-2
Morro Bay, CA 93442
Email: [email protected]
When corresponding or communicating with UFI
concerning your equipment, please include the model and
serial numbers.
UFI instruments and transducers are subject to continuous
improvement. We reserve the right to modify any design or
specification without notice and without incurring any
obligation.
ALL UFI TRANSDUCERS AND ELECTRODES ARE
COVERED BY OUR EXCLUSIVE "LIFELINE®
WARRANTY" AS OUTLINED BELOW
If your UFI transducer, electrode, or electrode tester ceases to
operate--regardless whether the cause is accidental, intentional, or
whatever---return it to us
. We will repair it or replace it with a new
one for a minimal handling charge, as listed below:
Model 1010, 1010C $25.00
Model 1020, 1020EC, 1020FC, 1110 $25.00
Model 1030, 1040, 1070, 1081FT $50.00
Model 1081 & 1081 SNP $11.00
Model 1089 MK II & MK III $65.00
Model 1130, 1131, 1132 $35.00
Prices subject to change
10-06-10