Piezo accelerometer for vibration analyse ?

[psykok]

Hi,

I saw some B&K accelerometer listed on ebay for more or less a decent price.
For example this one looks complet wth cable:
http://www.ebay.fr/itm/Bruel-and-Kjaer-Piezoelectric-charge-accelerometer-Type-4370-/151587530814?pt=FR_YO_MaisonJardin_Bricolage_ElectroniqueComposants&hash=item234b52283e

I don't find a lot of information about these capters and especially how to use it.
From what i understand with some accelerometer, a charge amplifier is need to interface it with the test instrument.

Do you have more information how it works?
My goal is to use a accelerometer coupled with a dynamic signal analyser to make virbation analyses .... Good or bad idea???


Alex

[Rerouter]

Once again with the above poster, it really comes down to the type and rate of the signal you are trying to measure, for down to clock ticks to up to about 3Khz, you can use a piezo buzzer films and a high impedance amplifier, (what i use to calibrate old auto clocks in under a minute as opposed to hours / days)

[psykok]

Hi,

i think I have to explain more about what I want to do ... I whant to mesure the vibration on hifi turnetable.
These kind of vibrarion are often coming from the motor but other environmental sources can also be in cause.

So I'm not realy sure about the frequency range I need for this king of job.

Currently I come to the b&k accelerometer because I saw that other peoples are using it to do exactly this job (fe: b&k 4517) ... But it seems that choosing the right capter will be not so easy as excepted.
Maybe an other way to go is using an accelerometer biard like the ADXL203.

Alex

[EEVblog]

I saw some B&K accelerometer listed on ebay for more or less a decent price.
For example this one looks complet wth cable:
http://www.ebay.fr/itm/Bruel-and-Kjaer-Piezoelectric-charge-accelerometer-Type-4370-/151587530814?pt=FR_YO_MaisonJardin_Bricolage_ElectroniqueComposants&hash=item234b52283e

B&K and PCB Piezotronics are two of the leading players.

I don't find a lot of information about these capters and especially how to use it.
From what i understand with some accelerometer, a charge amplifier is need to interface it with the test instrument.

There are two types of accelerometers, high impedance charge output and low impedance voltage output (they have charge am built in).
The voltage output ones need a constant current drive signal (usually 2mA or so). You can buy one or roll your own easily.
Charge sensors require special low triboelectric noise cables.
Not trivial to roll your own decent charge amp, so you usually buy one.

My goal is to use a accelerometer coupled with a dynamic signal analyser to make virbation analyses .... Good or bad idea???

Yes, that's standard industry practice and one of the main uses for DSA's.
You need features like coherence measurement.

[Rerouter]

first off i'm going to skip the part about the turn table as that may stir up some heated discussion that just kills threads..


moving on, considering the mass of the itmes involved and that you are measuring the turntable and not the read head, you are likely looking at no higher than 1Khz response to get everything, for the general stuff you would probably be closer to 100Hz, i am guessing your trying to measure some irregularities in the motor / shaft arrangement?

[psykok]

Yes it's exactly that.
In a first time, I don't want to mesure the vibration directly on the tonearm or the cartridge.

I just want to have a look on the motor, plinth ... To check how I can optimise my concepts and check I my mod are ok or not.



Alex

[robrenz]

This looks like a good candidate as it has a very high V/g and low noise level. Specs say it can resolve below 1mg if set for 60hz bandwidth.

[psykok]

This looks like a good candidate as it has a very high V/g and low noise level. Specs say it can resolve below 1mg if set for 60hz bandwidth.

Yes it's exactly the suggestion I made before.

Here is an example of using this module with a hp 3561a:
http://www.lencoheaven.net/forum/index.php?topic=15689.0

Alex