maybe this could help http://www.coleparmer.com/TechLibraryArticle/825
2012/1/12 Chris Lautre <chris.lau...@karusoft.com>: > Hi > > Thanks for your comments - I am finding out that Vibration sensing is pretty > specialised - seem to be mainly designed for rotating machines and various > vehicle applications where the sensor produces an RMS output over time. > > I will need to get much more info on the types of Vibration we will be > trying to identify (Frequency and Amplitude). > > Chris > > On 11/01/2012 21:06, Jerry Scharf wrote: > > Sorry, I had to jump in. > > Accelerometers are not good at measuring vibration. Accelerations are > measured instantaneously and are designed to operate above the noise floor > of the sensor. The accelerometers have filters to remove the noise to give > less erratic readings. The filters are a best guess by the designer of the > maximum meaningful rate of acceleration change (jerk) vs the amount of noise > to allow through. Most tend to lean toward heavily smoothed readings. > > Vibration sets the noise floor of acceleration in rough terms. You need > something that internally integrates the various frequencies of noise into > RMS and peak vibrational energy measurements. Depending on what you want, it > is often better to measure the vibration in multiple frequency bands. > > My guess the specific reading regimens are driven by the military and space > applications areas, they are the most demanding/knowledgeable about the > area. Things shake quite a bit on rockets and ships, and the equipment needs > to be able to survive that. I have never needed to deal with this, but can > get more information from a friend if others want it. At higher frequencies, > it becomes audio noise and then it's a whole different set of techniques and > constraints (microphones, SPL meters.) > > jerry > > On 01/11/2012 02:14 AM, Mick Sulley wrote: > > I have not actually tried it, but the Wii remote has accelerometers inside, > that may be a cheaper source than buying the components. > > Mick > > > On 11/01/12 06:35, Chris Lautre wrote: > > Hi > > Thanks for all your suggestions. Yes will use the DS2438. > > I am looking at some accelerometers that give out 4-20mA. > Seem to be very expensive. > Will continue looking for a cheaper sensor. > > Chris > > On 10/01/2012 20:57, Mark Richards wrote: > > On 1/10/2012 13:07, Chris Lautre wrote: > > I am thinking along the lines of finding a sensor that produces 4-20mA and > using a DS2450 to convert to 1 Wire. > > You might consider a DS2438 and using the current sense pins... As others > have stated, the 2450 is done for. > > How would you implement the sensor portion? Accelerometer? Intriguing.. > > /m > > > > > > ------------------------------------------------------------------------------ > Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex > infrastructure or vast IT resources to deliver seamless, secure access to > virtual desktops. With this all-in-one solution, easily deploy virtual > desktops for less than the cost of PCs and save 60% on VDI infrastructure > costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox > > > > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers > > > > > ------------------------------------------------------------------------------ > Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex > infrastructure or vast IT resources to deliver seamless, secure access to > virtual desktops. With this all-in-one solution, easily deploy virtual > desktops for less than the cost of PCs and save 60% on VDI infrastructure > costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox > > > > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers > > > ------------------------------------------------------------------------------ > RSA(R) Conference 2012 > Mar 27 - Feb 2 > Save $400 by Jan. 27 > Register now! > http://p.sf.net/sfu/rsa-sfdev2dev2 > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers > -- Roberto Spadim Spadim Technology / SPAEmpresarial ------------------------------------------------------------------------------ RSA(R) Conference 2012 Mar 27 - Feb 2 Save $400 by Jan. 27 Register now! http://p.sf.net/sfu/rsa-sfdev2dev2 _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
