Differential amplifier for laboratory measurements

June 03, 2013 // By Graham Prophet
A three-channel unit, Model 121, provides user-selectable parameters for measurement flexibility and features low input noise over wide bandwidth.

Measurement Specialties, specialist in sensor-based measuring of pressure/force, position, vibration, temperature, humidity and fluid properties, has added a 3-channel DC differential amplifier with an exceptionally low noise input of less than 20 µVrms. The Model 121 enables precision measurement on up to three channels simultaneously. Offering programmable gain up to 9,999 and user-defined output scaling, the new signal conditioner is suitable for use with bridge-type or differential output accelerometers, pressure transducers and load cells.

The unit’s low noise floor over a wide frequency bandwidth up 200 kHz makes for exceptional, accurate measurement of dynamic signals. The Model 121 is used in a variety of instrumentation lab, vibration and shock testing as well as process monitoring applications. Full scale accuracy is ±0.5% and linearity is ±0.1%. The Model 121 also features an auto-zero function that can be initiated by the operator to maximise voltage span in the data acquisition system. Each of the amplifier’s three channels uses a 9-pin D-sub connector. Input impedance is less than 1 M Ω. User-configurable shunt calibration can be applied via an internal or external resistor to any of the four legs of the transducer under test. Default shunt value is 150 k Ω. Testing parameters of the Model 121 can be set from the unit’s front panel via a push button interface. The unit stores settings for all functions on internal memory, and will automatically restore the last session’s settings on power-up.

Measurement Specialties; www.meas-spec.com/product/tm_product.aspx?id=9790