I am exploring the subject of a torsion spring sensor again. I say =
again because I have tried this approach before with no success at all.
I took a long band saw blade cut it to form a long vertical torsion =
spring. Attached both ends and pulled it tight.
In the middle of this spring I attached a boom. On both ends of the boom =
I attached a mass of equal value.
This boom would move around the vertical axis with very little effort, =
twisting the spring and then reversing to the other direction, rocking =
back and forth for a very long time. I don't remember how long but I =
think it was one hour plus.
The period of oscillation was controlled by moving the masses further =
out on the boom. Very long periods 30 seconds plus. To make a long =
story short, it did not record any earthquakes.
I think I did two things wrong. 1. The booms of equal mass cancelled =
the movement of each other. And in this configuration the earthquake =
would need to spin the house to move the masses.
2. The torsion spring needed to be tipped, not vertical.
Here is my next attempt. 1. I removed the boom, which formed a (+) on =
the vertical torsion spring and replace it with a short pendulum boom, =
this time on one side only.=20
it looks like a T on its side ( l-)
2. I contained the vertical torsion spring in a strong box about =
12"x12"x36". This retains all the parts and I can add tension to the =
spring, and mount the magnet and coil
3. I placed three leveling legs on the base of the box. Now I can tip =
the vertical spring (Off Vertical). Similar to tipping a Lehman, =
pitching up or down.
The spring now at an angle, contains a pendulum which is now (Off =
Horizontal).
The pendulum I am using is only about 6" long, and I get a period of =
about 5 seconds. I could get 20 seconds with a 18" boom. But my box =
could only accommodate a 6" boom.
It is now running as a test......I will see if it will record =
earthquakes.
It is sensitive to me moving around the room, and to drafts and tilts.
I have seen something similar somewhere on the web, but I can't fine it. =
This is all I could find. If someone has tried this please email me. =
Thanks, Ted
Torsion Seismometer Wood Anderson
I am exploring the subject of a torsion =
spring=20
sensor again. I say again because I have tried this approach =
before with=20
no success at all.
I took a long band saw blade cut it to =
form a long=20
vertical torsion spring. Attached both ends and pulled it =
tight.
In the middle of this spring I attached =
a boom. On=20
both ends of the boom I attached a mass of equal value.
This boom would move around the =
vertical axis with=20
very little effort, twisting the spring and then reversing to the other=20
direction, rocking back and forth for a very long time. I don't =
remember=20
how long but I think it was one hour plus.
The period of oscillation was =
controlled by=20
moving the masses further out on the boom. Very long periods =
30=20
seconds plus. To make a long story short, it did not record any=20
earthquakes.
I think I did two things wrong. =
1. The booms=20
of equal mass cancelled the movement of each other. And in this=20
configuration the earthquake would need to spin the house to move =
the=20
masses.
2. The torsion spring needed to be =
tipped, not=20
vertical.
Here is my next attempt. =
1. I=20
removed the boom, which formed a (+) on the vertical torsion spring and =
replace=20
it with a short pendulum boom, this time on one side only.
it looks like a T on its side ( =
l-)
2. I contained the vertical =
torsion spring in=20
a strong box about 12"x12"x36". This retains all the parts and I =
can add=20
tension to the spring, and mount the magnet and coil
3. I placed three leveling legs =
on the base=20
of the box. Now I can tip the vertical spring (Off=20
Vertical). Similar to tipping a Lehman, pitching up or =
down.
The spring now at an angle, contains a =
pendulum=20
which is now (Off Horizontal).
The pendulum I am using is only about =
6" long, and=20
I get a period of about 5 seconds. I could get 20 seconds with a =
18"=20
boom. But my box could only accommodate a 6" boom.
It is now running as a =
test......I will see=20
if it will record earthquakes.
It is sensitive to me moving around the =
room, and=20
to drafts and tilts.
I have seen something similar somewhere =
on the web,=20
but I can't fine it. This is all I could find. =
If=20
someone has tried this please email me. Thanks, =
Ted
Torsion Seismometer Wood =
Anderson
http://www.data.sc=
ec.org/Module/s3inset3.html