Hi Folks,  I have also built another Lehman.  I was disappointed that I =
did not get the 6.8M Japan May 7.

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.

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

Thanks for you suggestions.








Hi Folks,  I have also built =
another=20
Lehman.  I was disappointed that I did not get the 6.8M Japan May=20
7.
 
It has a proven hinge, top and =
bottom.  =20
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.
 
The period is set at 20 seconds, and =
this was=20
difficult, but I got it.
The coil is 3600 turn and magnets are =
also proven=20
design.
 
The boom is pointing East =
West.
The damping is as =
expected.
 
I did get this earthquake on two other =
sensors one=20
vertical and one tilt meter (just a 48" pendulum) swinging East=20
West.
 
Q.  Could it be over =
damped?
Q.  With the period at 20 second, =
could this=20
be too high? Too high for this earthquake?
Q.  Could it be the base on which =
the sensor=20
is position?  It is carpet, on top of the carpet are concrete =
blocks, SS=20
pads, and the sensor set on these.   I have used this on many =
other=20
short period sensor, and it works for those.
 
I see nothing wrong.   It =
does record all=20
the road construction, and my movements around the room.
 
Thanks for you =
suggestions.
 
Ted