| Tip of the
Month |
|
Importance of
mounting conditions when
calibrating...
A smooth, clean
mounting surface is critical to getting good results when
calibrating accelerometers. Make certain that BOTH mounting
surfaces (the reference and the sensor under test) have been
prepared properly. Eliminate all adhesive residue at the
interface and always use a little silicone compound with threaded
mounts. Even a human hair can prevent good results at high
frequencies - try experimenting with a stud mount accelerometer with
and without to see the
difference. |
| Newsletter
Archive |
May 2007 - Basics of Accelerometer Function; How Standards Link Together
June 2007 - Shear,
Compression, Flexure; ISO 16063 Overview
July 2007 - Accelerometer
Transduction Types (PE, PR, VC); Laser Primary Calibration
| |
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| Similarities between... |
...ICP and
charge.
 Piezoelectric
accelerometers can be broken down into two categories, defined by
their mode of operation: traditional charge mode
operation and the now standard ICP® mode
operation. These two
approaches accomplish the same end function of supplying a low
impedance varying voltage signal suitable for data acquisition. Internally amplified, ICP
accelerometers contain built-in microelectronic signal conditioning
rather than an external amplifier box. Accordingly, the ICP
approach accomplishes these same basic functions of a charge mode
vibration channel while it also simplifies the measurement with a
robust, noise immune, low impedance signal and reduces the risk of a
myriad of common measurement challenges. Charge mode
accelerometers contain only the piezoelectric crystal sensing
element with no electronics.
In charge mode vibration systems, the conversion of the high
impedance signal output from the crystals is accomplished remotely
in an expensive laboratory charge amplifier. Other than a few very high
temperature applications requiring remote location of the
electronics, most vibration measurement challenges are better served
by the simplified and lower cost operation of modern ICP
accelerometers.
Click here to learn more
about the similarities of charge output and ICP/voltage output
accelerometers. Adapted from an application note by James F.
Lally, co-founder of PCB Piezotronics, Inc.
|
| Basics of
ISO-16063-22... |
| ...Shock Calibration via Reference
Standard
 Part 22 of the
vibration and shock calibration standard covers "Shock
calibration by comparison to a reference transducer". Compared to the general
accelerometer calibration techniques discussed last month, shock
calibration is a specialty method. As such, there are a number
of accepted apparatus and methods depending on the desired shock
acceleration magnitude and pulse
width.
Click here to learn more
about the different techniques available for shock
calibration...
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| As always, your
satisfaction is at the pinnacle of our work. If you have questions that
you would like answered, please contact us and we'll be glad to help
out. Your question may
even be featured in a future month...
Sincerely, |
|
Michael J. Lally The Modal Shop
A PCB Group Company | |
