Model 839 is a high-sensitivity, low noise triaxial accelerometer which simultaneously measures acceleration and low-frequency vibration in three mutually perpendicular axial. 839 is triaxial capacitive accelerometer family utilizes a silicon Micro-Electro-Mechanical System (MEMS) variable capacitance sensing element. The sensing element of each axis consists of a very small inertial mass and a flexure element cantilever positioned between two plates. As the mass deflects under acceleration, the capacitance between these plate changes. AC excitation and synchronous amplitude demodulation circuitry contained in the accelerometer's internal signal conditioner provides an analog output signal proportional to the applied acceleration. This output signal is scaled as a voltage which is proportional to the applied acceleration. The output signal format is single-ended 2.5±2V. The accelerometer is powered by a single regulated supply between 8 to 36 Vdc. Thermal drift has been compensated by internal circuit for the best environment stability. The sensing element and electronics are contained in a lightweight housing with an integral cable terminated by pigtails or specified connector. Signal ground is isolated from the test object that benefit from the anodized aluminum housing. The accelerometer can be mounted by M3 metric screw or adhesive. 839 is well-suited for a wide variety of R&D applications requiring precision measurements and packaging for demanding application and handling needs.