Vibration pickup

Vibration Pickup Locknut or Vibration Pickup Spacer ... 

Common noise sources include vibration, pickup from 60-Hz lines, temperature variations, frequency or voltage fluctuations in the power supply, and the random arrival of photons at the detector. 

Carbon Resistors, Pressure Transducers and Vibration Pickups Used for Measurements of Temperature, Pressure and Vibration at Liquid Hydrogen Temperatures (1) 114... 

For the measurement and assessment of the effects of ground vibrations due to blasting on buildings (see DIN 4150, Part 3), the vibration pickups (transducers) for the three mutually perpendicular velocity components are installed in or on the foundation of the building or otherwise in the wall as close above ground level as possible and preferably on the side facing the blasting site. 

Direct Mass Measurement One type of densitometer measures the natural vibration frequency and relates the amplitude to changes in density. The density sensor is a U-shaped tube held stationaiy at its node points and allowed to vibrate at its natural frequency. At the curved end of the U is an electrochemical device that periodically strikes the tube. At the other end of the U, the fluid is continuously passed through the tube. Between strikes, the tube vibrates at its natural frequency. The frequency changes directly in proportion to changes in density. A pickup device at the cui ved end of the U measures the frequency and electronically determines the fluid density. This technique is usefiil because it is not affec ted by the optical properties of the fluid. However, particulate matter in the process fluid can affect the accuracy. 

However, the horizontal reading on one bearing will not show the same phase relationship as the vertical reading on the same bearing. This is due to the pickup axis being oriented in a different angular position, as well as the phase adjustment due to possible resonance. For example, the horizontal vibration frequency may be below the horizontal resonance of various major portions of machinery, whereas the vertical vibration frequency may be... 

The major piezoelectric applications are sensors (pickups, keyboards, microphones, etc.), electromechanical transducers (actuators, vibrators, etc ), signal devices, and surface acoustic wave devices (resonators, traps, filters, etc ). Typical materials are ZnO, AIN, PbTiOg, LiTaOg, and Pb(Zr.Ti)03 (PZT). 

Other cases of non-detector noise occur when the noise is introduced after the detector. These are usually a result of limitations of the instrument and in principle could be reduced by re-engineering the instrument. Examples include power line pickup, and mechanical vibrations affecting a sensitive part (generically called microphonics ). The magnitude of these would also tend to be independent of the signal level. 

The principle embodied in Mark 29 Anti-torpedo Device was as follows Two explosive streamers and a third streamer contg audio pickups sensitive to vibrations from the torpedo were to be trailed by a faired (joined so that external surfaces blend smoothly) cable attached to a paravane (See Note). When a torpedo passed over or under the detector streamer, one of the explosive streamers would be fired automatically to destroy the torpedo. The 2nd streamer would then be thrown automatically into the firing circle in readiness for a 2nd attack (Ref 2)... 

Little change of viscosity makes silicone liquids indispensable damping devices and parts of various measuring devices. A drop of silicone liquid put on a pointer index in the cockpit prevents vibration and keeps the index at rest this kind of damping is more efficient than complicated mechanical devices. Silicone damping liquids are also used in speedometers, amperemeters, voltmeters and gasometers, in relays and breakers, in acoustic pickups. 

Many sources of noise can be overcome by careful design, such as the use of shielding to prevent pickup of random voltages, smoothing of power supplies to obviate the effect of main voltage variations, and the use of shock absorbers to reduce mechanical vibration. Other sources of noise can be avoided by simple precautions, such as avoiding defective components, poor contacts, leaky insulations, and temperature fluctuations which adversely affect the noise of ampliflers and photomultipliers (W8). 

The complex mechanical impedance can be obtained by measuring force, velocity, and their phase difference using probes or pickups attached to the transducer at suitable points [144], This method is very convenient with solids [52] (sometimes the most accurate), but not with liquids, although in this case it can be a convenient method of checking the performance of a transducer. The output from an accelerometer or strain-sensitive pickup gives information on resonant frequency and vibrational amplitude. However subsequent correlation with the power transmitted to the sonicated medium is not straightforward. 

The mechanical vibration of the probe is transferred through a second welded node point along the upper spring rod to the pickup end of the detector. The pick-up end consists of an armature and coil arrangement which is similar to that of the driver end one exception being that the stator of the pick-up coil is a per-... 

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