PSN-L Email List Message
Subject: Re: Seismograph for school
From: "tchannel" tchannel@..............
Date: Sun, 1 Oct 2006 22:12:06 -0600
Hi Bob, Thanks for the great picture. I really liked your ideas and =
also the great one that Chris made.
Chris posted a drawing showing the magnet layout. Two magnets on top, =
end to end N to S, I think, and on the bottom two magnets end to end S =
to N. I find they make these magnets with the N and S poles in various =
arrangement. I don't remember the terms
but are your poles on the ends or on the Axially (through 6mm =
thickness)? In other words, laying flat, face up, North and flip it =
over and that side is South?
I made my first sensor, using a cow magnet and a coil in the shape of a =
spool, the cow magnet's, North pole, only fits into the spool hole, to =
the center point. If the pendulum move right, the North pole moves from =
center to the end of the spool, if it move left the North pole moves =
from the center of the spool to the entrance of the spool. It does =
work, but I see these are much better arrangement.
After reading these postings, I have a much better ideas about the coil =
size and proper wire size. On the other hand I see picture of huge huge =
magnets and coil. Is there a measurement in mv's or other test to tell =
if one has made a coil/magnet arrangement which is proper in output?
Thanks, for the ideas, Ted
----- Original Message -----=20
From: Bobhelenmcclure@..........
To: psn-l@.................
Sent: Sunday, October 01, 2006 7:21 PM
Subject: Re: Seismograph for school
Hi all,
I agree with Chris Chapman on the design of magnets and coils for =
horizontal sensors. Those who have an interest in building their own =
sensors should take a look at mine on John Lahr's web site, especially =
page http://www.jclahr.com/science/psn/mcclure/horiz2.html
I operate three sensors for Z, N, and E. They are adjusted to fairly =
short natural periods, ranging from 5 to 14 seconds. I extend their =
effective period to 24 seconds by a digital filter of my own design, =
with excellent results.
The magnets I recommend are available for $5.50 each, 50mm x 18mm x =
6mm block magnet, from http://www.gaussboys.com You will need four of =
them and two pieces of 1/4 inch flat steel, two inches by three inches, =
and four steel bolts to make a magnet assembly. You do not necessarily =
need separate damping magnets. Just shunt the pickup coil with the =
appropriate resistance.
Bob McClure
Hi Bob, Thanks for the great picture. I really liked =
your ideas=20
and also the great one that Chris made.
Chris posted a drawing showing the magnet layout. Two magnets =
on top,=20
end to end N to S, I think, and on the bottom two magnets end to end S =
to=20
N. I find they make these magnets with the N and S poles in =
various=20
arrangement. I don't remember the terms
but are your poles on the ends or on the Axially (through 6mm=20
thickness)? In other words, laying flat, face up, North and =
flip it=20
over and that side is South?
I made my first sensor, using a cow magnet and a coil in the shape =
of a=20
spool, the cow magnet's, North pole, only fits into the spool =
hole, to the=20
center point. If the pendulum move right, the North pole =
moves from=20
center to the end of the spool, if it move left the North pole moves =
from the=20
center of the spool to the entrance of the spool. It does =
work, but=20
I see these are much better arrangement.
After reading these postings, I have a much better ideas about the =
coil=20
size and proper wire size. On the other hand I see picture of huge =
huge=20
magnets and coil. Is there a measurement in mv's or other =
test to=20
tell if one has made a coil/magnet arrangement which is proper in =
output?
Thanks, for the ideas, Ted
----- Original Message -----
Sent: Sunday, October 01, 2006 =
7:21=20
PM
Subject: Re: Seismograph for =
school
Hi all,
I operate three sensors for Z, N, and E. They are adjusted =
to=20
fairly short natural periods, ranging from 5 to 14 seconds. I extend =
their=20
effective period to 24 seconds by a digital filter of my own design, =
with=20
excellent results.
The magnets I recommend are available for $5.50 each, 50mm =
x 18mm=20
x 6mm block magnet, from
http://www.gaussboys.com =
You will=20
need four of them and two pieces of 1/4 inch flat steel, two inches by =
three=20
inches, and four steel bolts to make a magnet assembly. You do not =
necessarily=20
need separate damping magnets. Just shunt the pickup coil with the =
appropriate=20
resistance.
Bob McClure
Locust Valley, NY
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