AC/DC Strain Gage Amplifiers
for Interfacing Data Acquisition Systems - Model LP122 Series

Model LP122 AC/DC Strain Gage Amplifier features high gain, low noise, stabilized DC amplification with versatile input switching to permit operation as an AC amplifier. This new amplifier has touch-pad controls.

The LP122 is intended to provide a signal conditioning interface for data acquisition systems, oscilloscopes and other devices.

Transducer excitation, balancing circuitry, amplification and filtering are standard features. With appropriate sensors, the LP122 can process signals such as pressure, force, temperature and many others. The AC input positions provide an excellent interface for EEG, EMG, EOG, ECG and other bioelectric signals.

Some typical applications include multiple channel in-vitro tissue bath studies, cardiovascular measurements, pulmonary mechanics, gut motility studies and many more.

A complete, stand-alone data acquisition and analysis system can be created by combining the LP511 High Performance AC Amplifier with the LP122 AC/DC Preamplifier and the PolyVIEW16 Data Acquisition and Analysis Software Package.

The bench-top unit is enclosed in a compact, rugged all-metal cabinet that is easy to stack vertically or horizontally. Optional rackmount hardware allows the unit to be mounted in a standard 19" rack while using only 1.75" of vertical space. All models require a Grass medical-grade regulated power supply which provides highly regulated ▒12 VDC.

Amplification   50 minimum to 50,000 maximum
Amplification Settings   10 settings of 50, 100, 200, 500, 1,000, 2,000, 5,000, 10,000, 20,000, 50,000
Input Selections
DC   For DC bioelectric potentials from electrodes and for interfacing transducers
AC   For AC coupling of bioelectric potentials from electrodes and AC coupling transducers. Selectable time constants of 0.01, 0.1, 1 and 10 seconds
Input Impedance   1 Mohm, differential
Balance Voltage   ▒50 mV DC, ▒5% accuracy
Coarse Control   x0.1 and x5, selectable
Fine Control   10-turn potentiometer provides 0.1 and 5 mV/turn
Drift   Less than 1 ÁV/hour after thermal stabilization
With Grass FT03
Force Transducer
  5 mg/hr (typical)
High (cutoff frequencies, -6 dB)   3,000, 300, 100, 30, 10, 1, 0.3, 0.1 Hz
Line Filter   Notch-type filter (50/60 Hz selectable with internal switch)
Time Constants   0.01, 0.1, 1 and 10 seconds, selectable. Corresponding to frequencies of 10, 1, 0.1 and 0.01 Hz
Output Connector   BNC, front panel
Load Tolerance   5 kohms or greater
Maximum Output   ▒5.0 volts
Output Level   Adjustable to zero with the balance control
Noise   5 µV peak to peak, referred to input (100 Hz)
CMR (Common
Mode Rejection)
  20,000:1 (86 dB) at 100 Hz
Physical Size
LP122   11.25" W x 1.75" H x 6.2" D
(28.6 cm x 4.5cm x 15.8 cm)
Weight   2.5 lbs. (1.2 kg)
Safety   EN 61010-1:2001, UL 61010A-1, CSA C22.2 No. 1010.1-92
EMC   FCC Part 15, Subpart B, Class A, EN 61326:1998 Class A
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Model LP122 Amplifier

Amplification from 50 to 50 k for processing of a wide range of bioelectric signals
AC and DC Input extends versatility by providing excitation for transducers and, with convenient switching to AC, supports EEG, EMG, ECG and other signals
▒50 mV Balance Voltage simplifies transducer balancing and provides precise measurements of offset potentials
Very low drift; less than 1 microvolt/hour minimizes time-consuming rebalancing procedures
Regulated transducer excitation voltage
Compatible with all Grass Transducers

Up to ±5 volts output
Model LP122   AC/DC strain gage amplifier, bench-top cabinet, includes manual (power supply required)
Model RPS312RX   Medical-grade power supply for up to 8 channels, bench-top style
  Medical-grade power supply for up to 8 channels, rackmount style
Optional Accessories:
Model SRS   Stimulate/Record Switching Unit
Model TAC-8   Transducer cable, 8-foot length (2.4 m) for connection to Grass FT03, FT10, PT5
Model TAC-9   Transducer cable, 1-foot length (0.3 m) for connection to SCA-1, TPA Adaptors, and P23XL, P10EZ, PT300 Pressure Transducers
Model CAB-21572   3-lead input cable, 8-foot length (2.4 m)
Model CAB-21826   Power supply cable for "daisy-chaining" power to additional amplifiers, 1-foot length (0.3 m)
Model LP1BT-1   Adjustable bench-top stand
to mount one amplifier
Model LP1BT-2   Adjustable bench-top stand
to stack two amplifiers
Model LP1RK   Rackmount conversion kit to mount one LP122 amplifier in 19" rack