Hi Chris, Yes the coil is on the arm and the magnet(assembly) is on the =
baseplate. This is a Lehman similar to the one you built.  Just to =
repeat myself, it is now 6:30 pm here and the trace has gone from =
daytime noise, to very still and will remain quiet until appx 8:37 to =
8:50am
Nothing appears on the helicorer, except earthquakes, during the night.  =
So I don't think the sensor is sticking etc, at night all is working =
perfectly.
The noise doesn't start exactly on the minute, each morning, I see no =
pattern, other than the first noise starts around 8:37 am all day even =
on Sundays and Holidays. =20
There is some sort of pumping? station one mile away, I don't even know =
what it is but it has a large engine on a concrete slab, and a block =
building next to the outdoor equipment.  Maybe I should drive over there =
at 8:33am, and see if the ground shakes.


(Is the pickup coil on the moving arm and the magnet on the floor / =
baseplate?)

Chris, Now on the zero length spring, do I understand that if I hang the =
spring, add enough wt to start it to extend, then add 2# and measure, =
then add another 2# and measure, continue doing this.........say the =
first 2# expanded 1" the next 2# expanded another 1"
If I did this 5 times, 2+2+2+2+2=3D 10#  The expansions would be =
1"+1"+1"+1"+1"=3D 5"?
In other words the same force would be required to move the same =
distance thought out the length of expansion?
If so, is this why they use a zero length springs on the vertical =
sensors so movement is uniform?
The length is not so important 20" vs 28" but it need so pull evenly, vs =
easy at first and get harder at the end?





-----Original Message-----
From: psn-l-request@.............. =
[mailto:psn-l-request@................. Behalf Of ChrisAtUpw@.......
Sent: Wednesday, November 29, 2006 5:29 PM
To: psn-l@..............
Subject: Re: School project


In a message dated 2006/11/29, tchannel@.............. writes:


  I am still trying to eliminate my daytime noise, or at least identify =
it. It was suggested I remove the magnet from the coil area to see if =
the noise continued, if so it might be electrical, like RF, =
communications etc. using the coil and cables as antenna. During a noisy =
hour I remove the magnet, from the coil.  All the noise disappeared, the =
helicorer was just a flat line. After a while, I reinstalled the magnet =
surrounding the coil and the noise reappeared. Note: I only get these =
spikes between 8am and 5pm, the night time hours are very quiet.
  Q.  Should I conclude that this means that it can not be electrical, =
ie, radio interference, but must be something creating vibrations?


Hi Ted,

       This suggests very strongly that it is not RFI or pulse feedback =
from the power wiring.=20
       What is the construction of your seismometer? Is the pickup coil =
on the moving arm and the magnet on the floor / baseplate?


  Q. On a different subject. Thanks to your input, I now have a better =
understanding of LaCoste zero length spring suspension, and how it is =
applied.
  But I don't understand (what is zero length) or how to find if a =
spring is zero length.  Perhaps someone could walk me thru this using a =
"screen door spring" as an example.


       Extension springs are wound with a considerable internal tension =
- you have to pull them fairly hard to get them to extend at all.=20
       You hang the spring vertically and measure the distance between =
the loop ends. Then you add just enough weight to start to extend the =
spring, measure the separation, increase the weight etc until you have =
maybe 5 points of length vs weight. Then you plot the points on a graph =
and extend the line joining them back to the axis. If the line passes =
through the zero weight / zero length point, you have a zero length =
spring. Hopefully, it will give a -ve length for a zero load.

       Regards,









Hi Chris, Yes the coil is on the arm =
and the=20
magnet(assembly) is on the baseplate. This is a Lehman similar to the =
one you=20
built.  Just to repeat myself, it is now 6:30 pm here and the trace =
has=20
gone from daytime noise, to very still and will =
remain quiet until=20
appx 8:37 to 8:50am
Nothing appears on the helicorer, =
except=20
earthquakes, during the night.  So I don't think the sensor is =
sticking=20
etc, at night all is working perfectly.
The noise doesn't start exactly on the =
minute, each=20
morning, I see no pattern, other than the first noise starts around 8:37 =
am all=20
day even on Sundays and Holidays.  
There is some sort of pumping? station =
one mile=20
away, I don't even know what it is but it has a large engine on a =
concrete slab,=20
and a block building next to the outdoor equipment.  Maybe I should =
drive=20
over there at 8:33am, and see if the ground shakes.
 
 
(Is the pickup coil on the moving arm =
and the=20
magnet on the floor / baseplate?)

Chris, Now on the zero length spring, do =
I=20
understand that if I hang the spring, add enough wt to start it to =
extend, then=20
add 2# and measure, then add another 2# and measure, continue doing=20
this.........say the first 2# expanded 1" the next 2# expanded another=20
1"
If I did this 5 times, 2+2+2+2+2=3D =
10#  The=20
expansions would be 1"+1"+1"+1"+1"=3D 5"?
In other words the same force would be =
required to=20
move the same distance thought out the length of=20
expansion?
If so, is this why they use a zero =
length=20
springs on the vertical sensors so movement=20
is uniform?
The length is not so important 20" vs =
28" but it=20
need so pull evenly, vs easy at first and get harder at the =
end?



 
 
 
-----Original Message-----
From: =
psn-l-request@.................
[mailto:psn-l-request@...............On Behalf Of=20
ChrisAtUpw@.......
Sent: Wednesday, November 29, 2006 5:29 =

PM
To: psn-l@..............
Subject: Re: School=20
project


In a =
message dated=20
2006/11/29, tchannel@.............. writes:


I am still trying to eliminate my daytime noise, or at =
least=20
  identify it. It was suggested I remove the magnet from the coil area =
to see if=20
  the noise continued, if so it might be electrical, like RF, =
communications=20
  etc. using the coil and cables as antenna. During a noisy hour I =
remove the=20
  magnet, from the coil.  All the noise disappeared, the helicorer =
was just=20
  a flat line. After a while, I reinstalled the magnet surrounding the =
coil and=20
  the noise reappeared. Note: I only get these spikes between 8am and =
5pm, the=20
  night time hours are very quiet.
Q.  Should I conclude that =
this means=20
  that it can not be electrical, ie, radio interference, but must be =
something=20
  creating vibrations?


Hi=20
Ted,

       This suggests very =
strongly=20
that it is not RFI or pulse feedback from the power wiring.=20

       What is the construction of =
your=20
seismometer? Is the pickup coil on the moving arm and the magnet on the =
floor /=20
baseplate?


Q. On a different subject. Thanks to your input, I now =
have a=20
  better understanding of LaCoste zero length spring suspension, and how =
it is=20
  applied.
But I don't understand (what is zero length) or how =
to find if=20
  a spring is zero length.  Perhaps someone could walk me thru this =
using a=20
  "screen door spring" as an example.


       Extension =
springs are=20
wound with a considerable internal tension - you have to pull them =
fairly hard=20
to get them to extend at all. 
       =
You hang=20
the spring vertically and measure the distance between the loop ends. =
Then you=20
add just enough weight to start to extend the spring, measure the =
separation,=20
increase the weight etc until you have maybe 5 points of length vs =
weight. Then=20
you plot the points on a graph and extend the line joining them back to =
the=20
axis. If the line passes through the zero weight / zero length point, =
you have a=20
zero length spring. Hopefully, it will give a -ve length for a zero=20
load.

      =20
Regards,

       Chris =
Chapman=20