Gary,

I am curious.

What are typical times for Lehman half-life decay?

What are the main causes  of decay?

Rob

Gary Lindgren wrote:
> Jon,
> Without damping give the boom a light touch, what is the natural period.
> Count how many seconds it takes to make one cycle. Then count how long it
> takes for the displacement to go from one centimeter to 1/2 centimeter. This
> will tell you how much friction you have in your sensor.
> Gary
>
>
>
>
> -----Original Message-----
> From: psn-l-request@.............. [mailto:psn-l-request@............... On
> Behalf Of Jón Frímann
> Sent: Wednesday, April 15, 2009 4:26 PM
> To: psn-l@..............
> Subject: RE: Changes to my Lehman sensor
>
> Hi
>
> There is a peak around 0.6Hz, it might be the sensor it self that peaks
> like that. But it might also be natrual forces in my area that create
> this peak. I am not sure yet what natrual frequancy of the sensor is.
>
> Regards.
> Jón Frímann.
>
> On miđ, 2009-04-15 at 15:53 -0700, Gary Lindgren wrote:
>   
>> Jon,
>> What is the period length of your Lehman sensor. Were you able to measure
>> how long it takes for the boom displacement to drop by 1/2 after giving it
>>     
> a
>   
>> light touch and this would be without damping in place.
>> Gary
>>
>>
>>
>>
>> -----Original Message-----
>> From: psn-l-request@.............. [mailto:psn-l-request@...............
>>     
> On
>   
>> Behalf Of Jón Frímann
>> Sent: Wednesday, April 15, 2009 11:20 AM
>> To: psn-l@..............
>> Subject: RE: Changes to my Lehman sensor
>>
>> Hi
>>
>> Here are pictures of the latest changes to my lehman sensor. One of the
>> change is that the top now has a hindge to make it more movable. In
>> theory that should provide me with better frequancy. However. I
>> continune to get the peak at 0.6Hz, even with thoise changes. The damper
>> plate is now aluminum, not steel.
>>
>> I am not sure how well this works until I get a earthquake close to
>> Iceland or some where in the world.
>>
>> Pictures.
>>
>> http://www.jonfr.com/myndir/v/geology/seismometer/p4150001b.jpg.html
>>
>> Regards.
>>     
>
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