PSN-L Email List Message

Subject: Re: Another New Lehman
From: ChrisAtUpw@.......
Date: Fri, 9 May 2008 00:16:06 EDT


In a message dated 2008/05/09, tchannel1@............ writes:

> It has a proven hinge, top and bottom.   Proven in that I have used this 
> approach before several times and it was successful.  ball bearing for the 
> bottom and wire for the top.

Hi Ted,

       What have you used for the hard counterface for the ball bearing? I 
use either a polished tungaten carbide triangular tool tip or a SS scalpel 
blade, stuck in place with acrylic glue.

> The period is set at 20 seconds, and this was difficult, but I got it.

       This should not be difficult.

> The coil is 3600 turn and magnets are also proven design.
> The boom is pointing East West.
> The damping is as expected.
> I did get this earthquake on two other sensors one vertical and one tilt 
> meter (just a 48" pendulum) swinging East West.
>  
> Q.  Could it be over damped?
> Q.  With the period at 20 second, could this be too high? Too high for this 
> earthquake?
> Q.  Could it be the base on which the sensor is position?  It is carpet, on 
> top of the carpet are concrete blocks, SS pads, and the sensor set on these.  
>  I have used this on many other short period sensor, and it works for those.
>  
> I see nothing wrong.   It does record all the road construction, and my 
> movements around the room.

       You can easily check the damping. Push the boom 10 mm to one side with 
a pencil or similar and release it. It should swing about 1/2 mm past the 
zero position. I use a magnifying glass and a transparent ruler to observe this.

       You should have seen the Love waves.

       Regards,

       Chris Chapman   
In a me=
ssage dated 2008/05/09, tchannel1@............ writes:

It has a proven hinge, top and=20= bottom.   Proven in that I have used this approach before several=20= times and it was successful.  ball bearing for the bottom and wire for=20= the top.


Hi Ted,

       What have you used for the hard counter= face for the ball bearing? I use either a polished tungaten carbide triangul= ar tool tip or a SS scalpel blade, stuck in place with acrylic glue.
<= FONT COLOR=3D"#000000" BACK=3D"#ffffff" style=3D"BACKGROUND-COLOR: #ffffff"= SIZE=3D3 PTSIZE=3D12 FAMILY=3D"SANSSERIF" FACE=3D"Arial" LANG=3D"0">

The period is set at 20 second= s, and this was difficult, but I got it.


       This should not be difficult.

The coil is 3600 turn and magn= ets are also proven design.
The boom is pointing East West.
The damping is as expected.
I did get this earthquake on two other sensors one vertical and one tilt me= ter (just a 48" pendulum) swinging East West.

Q.  Could it be over damped?
Q.  With the period at 20 second, could this be too high? Too high for= this earthquake?
Q.  Could it be the base on which the sensor is position?  It is=20= carpet, on top of the carpet are concrete blocks, SS pads, and the sensor se= t on these.   I have used this on many other short period sensor,=20= and it works for those.

I see nothing wrong.   It does record all the road construction,=20= and my movements around the room.


       You can easily check the damping. Push=20= the boom 10 mm to one side with a pencil or similar and release it. It shoul= d swing about 1/2 mm past the zero position. I use a magnifying glass and a=20= transparent ruler to observe this.

       You should have seen the Love waves.
       Regards,

       Chris Chapman

[ Top ] [ Back ] [ Home Page ]