PSN-L Email List Message
Subject: Re: Damping Resistor
From: Geoffrey gmvoeth@...........
Date: Mon, 6 Feb 2012 18:18:48 +0000
The trouble with these government pubs is that
I do not have a decent reader for their
file types.
I will never understand why they don't use rich text files
or simply html or plain 7 bit text.
Something more universal than a snobby DOC file
which takes too much space on your machine
or cost too much money for the software to read it.
I do not like to MS stuff because they are too
involved when it comes to installing the software.
They almost always use special software
to make their documents.
I guess Ill stop crying now.
Regards,
geoff
On 2/6/2012 5:39 AM, Stephen Hammond wrote:
> Hi Geoff, I get the impression you are looking for a simple answer to a
> complex problem. Here is a simple answer: I use three HS10 geophones on my
> system and based on word of mouth input I received from a USGS tech in 1990
> he told me to start with two 500 ohm resisters in a t-pad arrangement just
> to get started and work up until I got the output I desired. That said,
> Chris is right-- you will need the specs from the manufacture if you want to
> setup your geophones with any kind of precision . Here are two links, one to
> a USGS report describing setting the damping values for the S and T
> resisters in a t-pad style damping (one resister across the coil output and
> one resister in series between the coil output and one of the inputs to the
> filter/amp). Here is a link to a USGS paper and calibration results for
> their sensors. http://geopubs.wr.usgs.gov/open-file/of99-434/
>
> Here is the link to the Stanford Geo lab calibration procedure for the L4C
> geophone. http://www-ssrl.slac.stanford.edu/lcls/technotes/lcls-tn-03-6.pdf
>
>
>
> I hope this helps, Regards Steve Hammond PSN San Jose, Aptos, CA.
>
>
>
>
>
>
>
> From: psnlist-request@.............. [mailto:psnlist-request@...............
> On Behalf Of chrisatupw@.......
> Sent: Sunday, February 05, 2012 4:42 PM
> To: psnlist@..............
> Subject: Re: Damping Resistor
>
>
>
> Subject: Damping Resistor
>
> Is anyone able to comment on this expression
> to get a value for the damping resistor ?
> .
> Hi Geoff,
> Most geophones use a copper coil former, which also forms part of
> the mass. Since this is moving in the magnetic field, damping currents
> are induced in it, giving maybe 0.4 critical damping. I think that your
> formula relates to a system with no inherent damping. The manufacturers
> supply response curves for a range of damping resistors.
> Regards,
> Chris
>
__________________________________________________________
Public Seismic Network Mailing List (PSNLIST)
To leave this list email PSNLIST-REQUEST@.............. with
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.
[ Top ]
[ Back ]
[ Home Page ]