Gary Lindgren gel@.................
Sent: Tue, 8 May 2012 5:26
Subject: RE: Time domain switches for earthquake detection



There is not much information, I tried, but here is the chip he is talking =
about. http://www.lumedynetechnologies.com/Accelerometer.html It has 20 bit=
 accuracy so it must have digital output. The picture shows 24 pins. I thin=
k one of the applications could some sort of inertial navigation system. It=
 could be very simple. And we could use it in seismometer sensor. I couldn'=
t find any application information online and I sent the company an e-mail =
requesting information but no reply yet.
Gary
=20
 Hi Gary,
=20
    Thanks. I could not find a data sheet or anything giving information on=
 how it works. Several of the on-line references on the site seem to have b=
een removed. Did you have any success ?
=20
    This looks like the patent, US6,763,718, using Google patent search.=20

    The previous types of MEMS accelerometer were high g range devices and =
did not give the low noise performance necessary for detecting earthquakes7=
 - they are maybe only useful for very strong motion detectors.   =20
=20
    The problems with 1/f amplifier noise were mentioned in the talk. See h=
ttp://earthquake.usgs.gov/regional/nca/seminars/2012-04-25/ I wonder if Ern=
ie Major knew that chopper amplifiers are immune to this ? Probably not.
=20
    DigiKey sell 44mm OD piezo buzzer disks 102-1170-ND for $1.51. You can =
make a very sensitive accelerometer with a 1 oz mass, working out to 4 seco=
nds period. These give a higher output voltage than a geophone.  See http:/=
/www.jclahr.com/science/psn/chapman/piezo/index.html=20

    Regards,

    Chris Chapman












=
Gary Lindgren gel@.................
m

Sent: Tue, 8 May 2012 5:26

Subject: RE: Time domain switches for earthquake detection











There=
 is not much information, I tried, but here is the chip he is talking about=
.. http://www.lumedynetechnologies.com/Accelerometer.html=
 It has 20 bit accuracy so it must have digital output. The picture shows 2=
4 pins. I think one of the applications could some sort of inertial navigat=
ion system. It could be very simple. And we could use it in seismometer sen=
sor. I couldn't find any application information online and I sent the comp=
any an e-mail requesting information but no reply yet.


Gary


 


 Hi Gary,


 


    Thanks. I could not find a data s=
heet or anything giving information on how it works. Several of the on-line=
 references on the site seem to have been removed. Did you have any success=
 ?


 


    This looks like the patent, US6,7=
63,718, using Google patent search. 


 


    The previous types of MEMS accele=
rometer were high g range devices and did not give the low noise perfo=
rmance necessary for detecting earthquakes7 - they are maybe only useful fo=
r very strong motion detectors.    


 


    The problems with 1/f amplif=
ier noise were mentioned in the talk. See http://earthquake.usgs.gov/regional/nca/seminars/2012-04-25/&=
nbsp;I wonder if Ernie Major knew that chopper amplifiers are immune to thi=
s ? Probably not.


 


    DigiKey sell 44mm OD piezo b=
uzzer disks 102-1170-ND for $1.51. You can make a very sensitive =
accelerometer with a 1 oz mass, working out to 4 seconds period. These =
;give a higher output voltage than a geophone.  See http://www.jclahr=
..com/science/psn/chapman/piezo/index.html 


 


    Regards,


 


    Chris Chapman