## PSN-L Email List Message

Subject: Re: Mass vs. Coil
From: tchannel1@............
Date: Wed, 18 Jul 2007 15:30:16 -0600

```Hi Jerry, A lot of these discussions go over my head, for sure!  However =
Someone usually explains its in terms I can understand.   A great thing =
about the group is there are many levels of education, and just as =
important, experiences.
Someone will answer your question, better than me, but let me try just =
from my experience.

If the coil was large enough, you might use it as your mass.  I have =
seen horz sensors with large and small masses, from 8 ounces to 5 lbs.  =
Your period, will not change because of your mass.  One  to two kgs has =
been recommended.  Someone said the more mass the less movement from air =
currents etc.  I have one horz with 3 lbs, one with 5 lbs both work well =
for me.  On my sensors, don't know why, 1 lbs seemed too lite and 6 lbs =
seemed too heavy.  You might try 3...?

On the vertical sensor the mass is whatever is necessary to balance the =
spring.  On my vertical, I placed a 1/4" threaded bolt and added washers =
until it balanced the spring at the correct position.=20

If you are about to build your first sensor, let me know, as I have two =
simple vertical versions, very low tech. which work well.

Good luck, Ted

----- Original Message -----=20
From: Jerry Payton=20
To: psn-l@.................
Sent: Wednesday, July 18, 2007 2:49 PM
Subject: Mass vs. Coil

You gentlemen are so much advanced and more educate than I that I =
almost hesitate to ask this question.  A lot of your discussions, =
especially math and physics, go right over my head.  However, here goes:

I have always wondered why a mass is needed.  Why could not the coil =
itself  be used as the mass on a pendulum seismometer? =20

If  I understand what I have read in my books (questionable), the size =
and weight of a mass has nothing to do with the period.  Futhermore, I =
believe the length of the pendulum and supporting spring or wire on a =
horizontal or vertical sensor matters more for obtaining the wanted =
period, excluding friction loses etc.  The coil is only the desired =
method of detecting movement.=20

Regards,
Jerry Payton

Hi Jerry, A lot of these discussions go =
over my=20
head, for sure!  However Someone usually explains its in terms I =
can=20
understand.   A great thing about the group is there are many =
levels=20
of education, and just as important, experiences.
better than me,=20
but let me try just from my experience.

If the coil was large enough, you might =
use it as=20
your mass.  I have seen horz sensors with large and small masses, =
from 8=20
ounces to 5 lbs.  Your period, will not change because of your =
mass.=20
One  to two kgs has been recommended.  Someone said the =
more=20
mass the less movement from air currents etc.  I have one horz with =
3 lbs,=20
one with 5 lbs both work well for me.  On my sensors, don't =
know why,=20
1 lbs seemed too lite and 6 lbs seemed too heavy.  You might try=20
3...?

On the vertical sensor the mass is =
whatever is=20
necessary to balance the spring.  On my vertical, I =
placed a 1/4"=20
it balanced=20
the spring at the correct position.

sensor, let me=20
know, as I have two simple vertical versions, very low tech. which work=20
well.

Good luck, Ted

----- Original Message -----

From:=20
Jerry =
Payton=20

To: psn-l@..............
Sent: Wednesday, July 18, 2007 =
2:49=20
PM
Subject: Mass vs. Coil

You gentlemen are so much advanced and more educate than I that I =
almost=20
especially=20
math and physics, go right over my head.  However, here =
goes:

I have always wondered why a mass is needed.  Why could =
not the=20
coil itself  be used as the mass on a pendulum seismometer?  =

If  I understand what I have read in my books =
(questionable), the=20
size and weight of a mass has nothing to do with the period.  =
Futhermore,=20
I believe the length of the pendulum and supporting spring or wire on =
a=20
horizontal or vertical sensor matters more for obtaining the wanted =
period,=20
excluding friction loses etc.  The coil is only the =
desired=20
method of detecting movement.

Regards,
Jerry Payton

```