PSN-L Email List Message
Subject: Re: Opinion on seismometer
From: Larry Cochrane lcochrane@..............
Date: Wed, 13 Jun 2007 18:58:58 -0700
Hi All,
This is a reminder that you can not send attachments to the PSN-L list. If you have a
file you would like to share with the group you will need to place it on a web/ftp
server somewhere and send the link to the file to the list. If you do not have access
to a web server I can place the file on my system.
If you have a PSN event file you would like to share with the group you can send them
to event@.............. as attachments. The event file(s) will show up on this page
http://www.seismicnet.com/cgi-dos/event.exe a few minutes after my mail server
receives the message.
Regards,
Larry Cochrane
Redwood City, PSN
Pete Rowe wrote:
> Hi all
> I sent the following message with a pdf of my
> recording but it bounced back as too large for the
> group. I'm not sure how to send it any other way.
> Pete
>
>
> Here is my recording of the Guatemalan quake today. As
> Jan mentioned, my seismometer is the size of a
> shoebox, has a three second period, is critically
> damped with a resistor across the coil, has almost no
> weight on the boom, and I can see a 7.0 anywhere on
> earth. The suspension is two fine steel wires (violin
> E string) both of which are in tension. This sits on
> the dirt under my house. The noise level is higher
> than normal today due to wind in the trees. Normally,
> I have a very quiet baseline. It has been running
> almost untouched since 1988.
>
> regards,
> Pete Rowe
> San Jose, CA
> --- Jan Froom wrote:
>
>> I can remember when Pete Rowe and I first started
>> playing around with
>> amateur seismometers... I built a large unit with a
>> long boom with a
>> very heavy mass. Pete built a little unit, with no
>> mass on his boom at
>> all. I had my unit mounted on three massive concrete
>> piers... Pete set
>> his unit on a scrap of 2X4 under his house...
>> Funny thing... we both got about the same results...
>> and Pete didn't
>> have half the problems I had.
>> Pete finally put a small fish weight on the end of
>> his boom... I sure...
>> simply to appease me.
>>
>> I've also come to the conclusion that the antique
>> seismometers I've
>> collected all have large masses and huge coils
>> simply because they had
>> to generate enough power to drive a pen motors
>> directly, with no
>> external amplification. With today's amplifiers and
>> technology you can
>> do a whole lot more with a whole lot less.
>>
>> Since the only response to my query about drum
>> recorders came from
>> Chris... I took his advice and took an aspirin and
>> thought about my
>> problem. I've decided to take advantage of the
>> antique nature of what I
>> have, and capitalize on that. Part of what I've
>> tried to inspire in the
>> kids I've worked with... is the simplicity of a
>> seismic monitoring
>> system... the simplicity of a whole lot of "complex"
>> scientific
>> devices... what better way then to let them see the
>> simple pieces up
>> close... and if it looks a bit "Rube
>> Goldbergish"... well that will be
>> kool too.
>>
>> Jan in Gilroy.
>>
>
>
>
>
>
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