From:=20
Mike =
Speed=20
Sent: Thursday, January 01, =
2004 7:33=20
AM
Subject: Re: STM-8 =
Questions
Dear Sir,
On the "Block Diagram of Hardware Store Broadband=20
Seismometer...", what is the value of the feedback resistor on =
A2 (I=20
see the value of the Integral Feedback resistor is =
107K)? I=20
assume that resistor is supposed to be connected to the output =
of A2,=20
but from the drawing there are just two dots there.
Greg
Do you Yahoo!?
Find out =
what made=20
the Top Yahoo! Searches of 2003
Subject: RE: A "new" seismo base plate adjustment screw/s approach
From: "Meredith Lamb" meredithlamb@.............
Date: Tue, 6 Jan 2004 22:25:56 -0700
Hi all,
Included herein is a reply from Chris Chapman in relation to this subject. The reason for
this approach is that Chris uses the AOL email system which can neither send to, or be
received from PSN. Meredith Lamb
----- Original Message -----
From: Meredith Lamb
To: psn-l
Sent: 12/6/2003 9:53:24 PM
Subject: A "new" seismo base plate adjustment screw/s approach
Hi all,
Have tried researching this on the PSN web site search function, but I see no reference.
It maybe nothing new...(?)...but it sure works great! Best of all, there is little to no adjustment
screw wobble, with quite solid firm movement.....and no base plate bolt threading (tapping)
to be done. The normal "fitting" of the nuts to the bolts, alone by themselves is quite loose
and non-exact....but not in this application.
Basically this approach uses a standard bolt and three nuts, but, the seismo base has
only some predetermined chamfer widening of the bolt hole/s that is larger than the bolt
(adjustment screw) diameter, but only wide enough to make contact with the chamfer on
the nuts.
The nuts themselves have 6 planes (hexagonal outer shape), and some chamfering on
the outside top/bottom outside edges. Non-chamfered nuts are useless.
One nut is above the other two; this is a locking nut only....which may or maynot be
absolutely necessary depending on how much tension the other two nuts are adjusted too.
A crude guide to trying/using this; could be the "base material" I used. It was actually
a hardened tool steel machinist "parallel", that had two holes through the item. The actual
hole/s were .5" in diameter but the chamfer was wider and made full contact with the nuts
chamfer (.575"). The actual bolt thread diameter was .311". Here, the hole drilling and
chamfer was done with a likely professional grade machine somewhere of course, but it
was likely done straight into the item without a lateral tilt offset. If your hole and chamfer is
done by hand, the bolt may not be exactly standing upright 180 degrees to the "base plate"
material when installed. Visually for this "model", I couldn't see any bolt tilt.
One nut is threaded on the bolt, then passed through the base material, and the other
nut is threaded on lightly finger tightened to where....the bolt can be turned (adjusted) but the
nuts don't. With the two nuts on the bolt thread, increased turning of "a" nut, narrows
the space for the inside bolt thread, and lessens the "normal" bolt freedom to wobble.
Increased finger tightening of "a" nut makes this "bolt wobble" almost nil, and of course
makes it harder to turn the bolt (adjustment screw), but the firmness of the approach
seems to enhance the mechanical stability quite noteably. One might call this a
holding/tension/friction adjustment nut. A wrench isn't needed of course for this or
the locking nut.
One may have a tough time trying to use non-chamfered holes for this approach;
most of my attempts failed with various material. Various large drills (movement
limited) could be used for creating a chamfer; but their is other tools for this also.
One "could" epoxy the nut/s. Epoxy one or both after adjusting the nut/s to your
satisfaction. Its possible the top nut "could" remain free of any cement, to adjust
the fitting tension on the nut to their satisfaction, whenever they wish
For smooth bolt thread movement action, I'd suggest that the bolt/s be re-die-ed to
eliminate burrs, or clogging matterial that might be in the threads. I'd look for a
straight bolt thread; theres no use buying a bent bolt.
One might also consider that in the base plate hole and between the nuts is a air
space that might serve as a "lubricant reservoir", for any of a variety of such lubricants
or types for various material. A thicker variety of non-liquifying grease might be a good
bet (auto grease) for the iron/steel bolts/nuts functioning over time, as well as anti-rust
prevention.
One might try this out on scrap material first before plunging into using it on the planned
for base plate installation. One doesn't need expensive adjustment bolts/nuts with this
route.
Merry Christmas and happy new year everyone!
Take care, Meredith Lamb
****** Chris Chapmans reply below:
12/19/03
Hi Meredith,
Ordinary grease is made from oil and soap. The soap decays with time, but some soaps are better than others. The high temperature Molybdenum disulphide grease used on cars is fairly good and the moving surfaces get coated with the solid MoS2 lubricant. Vaseline also lasts a very long time. Don't use graphite grease; it is inclined to promote corrosion.
The critical point is that the expansion coefficients of the adjustment bolt and the nut or threaded baseplate need to be identical. This greatly reduces any tendency for the adjustment to creep as the temperature changes.
You can buy large multi flute countersink cutters quite cheaply, but I am not sure that this angle is quite correct for the nuts. Countersinks may have angles of 60, 82, or 90 degrees, 90 being the most common. You can get drills with a cone of 118 degrees, but 135 degrees is more common. The ordinary drills with two flutes do not centre very well over a smaller hole and are inclined to chatter. You can get smoother cutting by using a drill press and opening up the hole first with a standard countersink. The bevel angle cut on nuts may not be very well defined. It seems to vary from 100 to 110 degrees in the ones that I have measured and the depth of the cut may be asymmetrical - check both ends of the nut.
Drilling an accurate clearance hole in the baseplate with a drill press and then sticking a nut onto the flat surface is another option and this gives a high strength glue joint.
You can buy special nuts which have a large 45 deg chamfer on one end. These should be excellent when used with holes shaped with a 90 deg multi fluted countersink cutter.
You can also buy special nuts designed for insertion into sheet metal. They are longer than ordinary nuts and are turned down to a small tube at one end. When used in sheet metal, the turned down end is inserted through a hole in the sheet and the end is splayed with a press or a ball hammer. However, they can also be pushed into a plain hole drilled in say Al plate and secured with epoxy or Loctite. You can use one at both ends of a hole drilled through thick plate. This can provide a very precisely aligned rigid mounting.
Another method of providing a thread in soft Al plate is to drill out a central clearance hole for the bolt and then use a 'special' counterbore cutter to drill a flat bottomed hole slightly smaller than the outer diameter of the nut, to the length of the nut. You then press in a nut into the hole, maybe adding epoxy or Loctite, using a vice or a press. The six corners of the nut bed into the softer Al quite easily.
To get epoxy to perform well, the surfaces need to conform closely and there needs to be an appreciable glue area. It does not hole a sharp edge very well.
One thing that I have been doing is to drill the end of the vertical adjusting screws with a centre drill. I then stick a Stainless Steel ball bearing into the V cup, with epoxy. The diameter of the bearing is slightly less than the tap drill size for the thread used eg use a 5 mm ball for a 6 mm OD thread. This seems to give a contact which does not change with time. The wide angle points which are sometimes used seem to 'bed into' the mounting plates and may wander a bit. The seismometer is mounted on 2" squares of 1/4" thick stainless steel bonded to a concrete floor.
I drill and tap the hole in the steel seismometer baseplate. I put a nut and a wavy washer on the bolt, screw it into position and tension the nut. You can get wavy washers in phosphor bronze and stainless steel. They look like a very thin ordinary washer but are bent to have three S shaped curves which act as a spring. A dab of rubber contact adhesive will keep the nut from rotating as the suspension is levelled and the wavy washer keeps the screw thread under tension.
Regards,
Chris Chapman
Hi all,
Included herein is a reply from Chris Chapman in relation to this subject. The reason for
this approach is that Chris uses the AOL email system which can neither send to, or be
received from PSN. Meredith Lamb
----- Original Message -----
Sent: 12/6/2003 9:53:24 PM
Subject: A "new" seismo base plate adjustment screw/s approach
Hi all,
Have tried researching this on the PSN web site search function, but I see no reference.
It maybe nothing new...(?)...but it sure works great! Best of all, there is little to no adjustment
screw wobble, with quite solid firm movement.....and no base plate bolt threading (tapping)
to be done. The normal "fitting" of the nuts to the bolts, alone by themselves is quite loose
and non-exact....but not in this application.
Basically this approach uses a standard bolt and three nuts, but, the seismo base has
only some predetermined chamfer widening of the bolt hole/s that is larger than the bolt
(adjustment screw) diameter, but only wide enough to make contact with the chamfer on
the nuts.
The nuts themselves have 6 planes (hexagonal outer shape), and some chamfering on
the outside top/bottom outside edges. Non-chamfered nuts are useless.
One nut is above the other two; this is a locking nut only....which may or maynot be
absolutely necessary depending on how much tension the other two nuts are adjusted too.
A crude guide to trying/using this; could be the "base material" I used. It was actually
a hardened tool steel machinist "parallel", that had two holes through the item. The actual
hole/s were .5" in diameter but the chamfer was wider and made full contact with the nuts
chamfer (.575"). The actual bolt thread diameter was .311". Here, the hole drilling and
chamfer was done with a likely professional grade machine somewhere of course, but it
was likely done straight into the item without a lateral tilt offset. If your hole and chamfer is
done by hand, the bolt may not be exactly standing upright 180 degrees to the "base plate"
material when installed. Visually for this "model", I couldn't see any bolt tilt.
One nut is threaded on the bolt, then passed through the base material, and the other
nut is threaded on lightly finger tightened to where....the bolt can be turned (adjusted) but the
nuts don't. With the two nuts on the bolt thread, increased turning of "a" nut, narrows
the space for the inside bolt thread, and lessens the "normal" bolt freedom to wobble.
Increased finger tightening of "a" nut makes this "bolt wobble" almost nil, and of course
makes it harder to turn the bolt (adjustment screw), but the firmness of the approach
seems to enhance the mechanical stability quite noteably. One might call this a
holding/tension/friction adjustment nut. A wrench isn't needed of course for this or
the locking nut.
One may have a tough time trying to use non-chamfered holes for this approach;
most of my attempts failed with various material. Various large drills (movement
limited) could be used for creating a chamfer; but their is other tools for this also.
One "could" epoxy the nut/s. Epoxy one or both after adjusting the nut/s to your
satisfaction. Its possible the top nut "could" remain free of any cement, to adjust
the fitting tension on the nut to their satisfaction, whenever they wish
For smooth bolt thread movement action, I'd suggest that the bolt/s be re-die-ed to
eliminate burrs, or clogging matterial that might be in the threads. I'd look for a
straight bolt thread; theres no use buying a bent bolt.
One might also consider that in the base plate hole and between the nuts is a air
space that might serve as a "lubricant reservoir", for any of a variety of such lubricants
or types for various material. A thicker variety of non-liquifying grease might be a good
bet (auto grease) for the iron/steel bolts/nuts functioning over time, as well as anti-rust
prevention.
One might try this out on scrap material first before plunging into using it on the planned
for base plate installation. One doesn't need expensive adjustment bolts/nuts with this
route.
Merry Christmas and happy new year everyone!
Take care, Meredith Lamb
****** Chris Chapmans reply below:
12/19/03
Hi Meredith,
Ordinary grease is made from oil and soap. The soap decays with time, but some soaps are better than others. The high temperature Molybdenum disulphide grease used on cars is fairly good and the moving surfaces get coated with the solid MoS2 lubricant. Vaseline also lasts a very long time. Don't use graphite grease; it is inclined to promote corrosion.
The critical point is that the expansion coefficients of the adjustment bolt and the nut or threaded baseplate need to be identical. This greatly reduces any tendency for the adjustment to creep as the temperature changes.
You can buy large multi flute countersink cutters quite cheaply, but I am not sure that this angle is quite correct for the nuts. Countersinks may have angles of 60, 82, or 90 degrees, 90 being the most common. You can get drills with a cone of 118 degrees, but 135 degrees is more common. The ordinary
drills with two flutes do not centre very well over a smaller hole and are inclined to chatter. You can get smoother cutting by using a drill press and opening up the hole first with a standard countersink. The bevel angle cut on nuts may not be very well defined. It seems to vary from 100 to 110 degrees in the ones that I have measured and the depth of the cut may be asymmetrical - check both ends of the nut.
Drilling an accurate clearance hole in the baseplate with a drill press and then sticking a nut onto the flat surface is another option and this gives a high strength glue joint.
You can buy special nuts which have a large 45 deg chamfer on one end. These should be excellent when used with holes shaped with a 90 deg multi fluted countersink cutter.
You can also buy special nuts designed for insertion into sheet metal. They are longer than ordinary nuts and are turned down to a small tube at on
e end. When used in sheet metal, the turned down end is inserted through a hole in the sheet and the end is splayed with a press or a ball hammer. However, they can also be pushed into a plain hole drilled in say Al plate and secured with epoxy or Loctite. You can use one at both ends of a hole drilled through thick plate. This can provide a very precisely aligned rigid mounting.
Another method of providing a thread in soft Al plate is to drill out a central clearance hole for the bolt and then use a 'special' counterbore cutter to drill a flat bottomed hole slightly smaller than the outer diameter of the nut, to the length of the nut. You then press in a nut into the hole, maybe adding epoxy or Loctite, using a vice or a press. The six corners of the nut bed into the softer Al quite easily.
To get epoxy to perform well, the surfaces need to conform closely and there needs to be an appreciable gl
ue area. It does not hole a sharp edge very well.
One thing that I have been doing is to drill the end of the vertical adjusting screws with a centre drill. I then stick a Stainless Steel ball bearing into the V cup, with epoxy. The diameter of the bearing is slightly less than the tap drill size for the thread used eg use a 5 mm ball for a 6 mm OD thread. This seems to give a contact which does not change with time. The wide angle points which are sometimes used seem to 'bed into' the mounting plates and may wander a bit. The seismometer is mounted on 2" squares of 1/4" thick stainless steel bonded to a concrete floor.
I drill and tap the hole in the steel seismometer baseplate. I put a nut and a wavy washer on the bolt, screw it into position and tension the nut. You can get wavy washers in phosphor bronze and stainless steel. They look like a very thin ordinary washer but are bent to have three S shaped curves which act as
a spring. A dab of rubber contact adhesive will keep the nut from rotating as the suspension is levelled and the wavy washer keeps the screw thread under tension.
Regards,
Chris Chapman
Subject: ebay auction
From: BOB BARNS royb1@...........
Date: Thu, 08 Jan 2004 10:10:49 -0500
Hi gang,
Ebay has an auction:
Kinemetrics Analog Accelerograph Seismograph
Item number: 2586933509
This ends 1/14/04
Bob
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: FYI cheap instrumentation confernece
From: sismos@..............
Date: Sun, 11 Jan 2004 22:27:25 +0000
Hi All,
cheap instrumentation confernece.
Just a note to announce a conference that I in conjucntion with the Jens
Havskov are putting on in my town of Volcan, Panama. The sessions are
mostly in Spanish and the main topic is how to make inexpensive seismic stations
and networks.
Jens is a seismic instrumentation professor at the University on
Bergen in Norway and visited me last summer. He liked my network and
array and suggested a conference and I took the bait. We have invited
two seismologist from each Central American country along with some
folks from Spain, Italy, the US and South America. We expect about 30
participants.
A quick and preliminary description is at:
www.volcanbaru.com/array/overview.html
Registration cost:
www.volcanbaru.com/array/confernce.html
If anyone has any questions or suggestion for content I am very open. The focus is
on inexpensive instrumentation.
Warmly,
Angel
Some information links below:
http://www.lib.utexas.edu/maps/americas/panama_relief.jpg
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Timming on the Serial ADC board
From: Arie Verveer greensky@............
Date: Mon, 12 Jan 2004 21:42:49 +0800
Hi all, I was looking at the specifications of "Larry's" Serial ADC board
and noticed the "WWV" option. On the self I have a "Garmen GPS -25"
evaluation board and was planning to make a circuit to mimic the
"WWV" minute tone and feed this into the board. Has anyone done
anything similar ?
Also is it possible to feed a 600 ms pulse into the Serial ADC board
as you can do with the ISA A/D board? Basically I want to use what
I've got on hand other than purchasing a new "Garmen 16" GPS.
Cheers
Arie
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: conference dates
From: sismos@..............
Date: Mon, 12 Jan 2004 15:39:07 +0000
Hello All,
Well several folks have written to let me know that I failed to
mention the dates of the cheap instrument conference. and they were
right! The dates are:
March 8 through 12 of 2004.
I have also update the docs on the web
A quick and preliminary description is at:
www.volcanbaru.com/array/overview.html
Registration cost:
www.volcanbaru.com/array/confernce.html
angel
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: check this out
From: sismos@..............
Date: Mon, 12 Jan 2004 23:22:43 +0000
Hello All
check this out:
the headline reads at UC Berkley news:
Earthquakes can be predicted months in advance
http://www.ucnewswire.org/news_viewer.cfm?story_PK=3487&
http://www.ucnewswire.org/news_viewer.cfm?story_PK=3499&
Angel
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Timming on the Serial ADC board
From: sismos@..............
Date: Mon, 12 Jan 2004 23:26:07 +0000
Hello Arie,
Good to hear from you.
Mauro has a card that converts GPS to the euro radio time signal
http://www.infoeq.it/doc16_e.htm
angel
Monday, January 12, 2004, 1:42:49 PM, you wrote:
AV> Hi all, I was looking at the specifications of "Larry's" Serial ADC board
AV> and noticed the "WWV" option. On the self I have a "Garmen GPS -25"
AV> evaluation board and was planning to make a circuit to mimic the
AV> "WWV" minute tone and feed this into the board. Has anyone done
AV> anything similar ?
AV> Also is it possible to feed a 600 ms pulse into the Serial ADC board
AV> as you can do with the ISA A/D board? Basically I want to use what
AV> I've got on hand other than purchasing a new "Garmen 16" GPS.
AV> Cheers
AV> Arie
AV> __________________________________________________________
AV> Public Seismic Network Mailing List (PSN-L)
AV> To leave this list email PSN-L-REQUEST@.............. with
AV> the body of the message (first line only): unsubscribe
AV> See http://www.seismicnet.com/maillist.html for more information.
--
Best regards,
sismos mailto:sismos@..............
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: A "new" seismo base plate adjustment screw/s approach
From: "Meredith Lamb" meredithlamb@.............
Date: Mon, 12 Jan 2004 20:06:04 -0700
Hi all, Forgive this mistake; but I left out portions of the latest draft on the subject by Chris
Chapman. The subject is quite relivant to amateur seismology. Below is the complete draft......
Hi Meredith,
Ordinary grease is made from oil and soap. The soap decays with time, but some soaps
are better than others. The high temperature Molydenum disulphide grease used on cars
is fairly good and the moving surfaces get coated with the solid MoS2 lubricant. Vaseline
also lasts a very long time. Don't use graphite grease; it is inclined to promote corrosion.
The critical point is that the expansion coefficients of the adjustment bolt and the nut or
threaded baseplate need to be identical. This greatly reduces any tendenccy for the
adjustment to creep as the temperature changes.
You can buy large mulit flute countersink cutters quite cheaply, but I am not sure that
this angle is quite correct for the nuts. Countersinks may have angles of 60, 82, or 90
degrees, with 90 being the most common. You can get drills with a cone of 118 degrees,
but 135 degrees is more common. The ordinary drills with two flutes do not centre very
well over a smaller hole and are inclined to chatter. You can get smoother cutting by
using a drill press and opening up the hole first with a standard countersink. The bevel
angle cut on nuts may not be very well defined. It seems to vary from 100 to 110 degrees
in the ones that I have measured and the depth of the cut may be asymmetrical - check
both ends of the nut. The 5/16" UNF bolts seem to have asymmetrical chamfers, but
these are closer to 90 degree. The outside tips have a ridge on them, so the outside
diameter of the countersunk hole should be the same as that measured across the flats
- 0.500" in this case.
Drilling an accurate clearance hole in the baseplate with a drill press and then sticking
a nut onto the flat surface is another option and this does give a high strength glue joint.
You can buy special nuts which have a large 45 degree chamfer on one end. These
should be excellent when used with holes shaped with a 90 degree multi fluted
countersink cutter.
You can also buy special nuts designed for insertion into sheet metal. They are longer
than ordinary nuts and are turned down to a small tube at one end. When used in sheet
metal, the turned down end is inserted through a hole in the sheet and the end is splayed
with a press or a ball hammer. However, they can also be pushed into a plain hole
drilled in say aluminum plate and secured with epoxy or loctite. You can use one at
both ends of a hole drilled through thick plate. This can provide a very precisely
aligned rigid mounting.
Another method of providing a thread in solft aluminum plate is to drill out a central
clearance hole for the bolt and then use a "special" counterbore cutter to drill a flat
bottomed hole slightly smaller than the outer diameter of the nut, to the length of the
nut. You then press in a nut into the hole, maybe adding epoxy or Loctite, using a vice
or a press. The six corners of the nut bed into the softer aluminum quite easily.
For epoxy to give a high strength joint, the surfaces need to conform closely and there
needs to ba an appreciable glue area. Epoxy will not stick a sharp edge to a conical
hole very well.
One thing that I have been doing is to drill the end of the vertical adjusting screws with
a centre drill. I then stick a stainless steel ball bearing into the V cup, with epoxy. The
diameter of the bearing is slightly less than the tap drill size for the thread used, i.e., use
a 5 mm ball for a 6 mm OD thread. This seems to give a contact which does not change
with time. The wide angle points which are sometimes used seem to "bed into" the
mounting plates and may wander a bit. The seismometer is mounted on 2" squares of
1/4" thick stainless steel bonded to a concrete floor.
I drill and tap the hole in the steel seismometer baseplate. I put a nut and a wavy
washer on the bolt, screw it into position and tension the nut. You can get wavy /
crinkle washers in phosphor bonze and stainless steel. They look like a very thin
ordinary washer but are bent to have three S shaped curves which act as a spring. A
dab of rubber contact adhesive will keep the nut from rotating as the suspension is
leveled and the wavy washer keeps the screw thread under tension.
Regards, Chris Chapman
Hi all, Forgive this mistake; but I left out portions of the latest draft on the subject by Chris
Chapman. The subject is quite relivant to amateur seismology. Below is the complete draft......
Hi Meredith,
Ordinary grease is made from oil and soap. The soap decays with time, but some soaps
are better than others. The high temperature Molydenum disulphide grease used on cars
is fairly good and the moving surfaces get coated with the solid MoS2 lubricant. Vaseline
also lasts a very long time. Don't use graphite grease; it is inclined to promote corrosion.
The critical point is that the expansion coefficients of the adjustment bolt and the nut or
threaded baseplate need to be identical. This greatly reduces any tendenccy for the
adjustment to creep as the temperature changes.
You can buy large mulit flute countersink cutters quite cheaply, but I am not sure that
this angle is quite correct for the nuts. Countersinks may have angles of 60, 82, or 90
degrees, with 90 being the most common. You can get drills with a cone of 118 degrees,
but 135 degrees is more common. The ordinary drills with two flutes do not centre very
well over a smaller hole and are inclined to chatter. You can get smoother cutting by
using a drill press and opening up the hole first with a standard countersink. The bevel
angle cut on nuts may not be very well defined. It seems to vary from 100 to 110 degrees
in the ones that I have measured and the depth of the cut may be asymmetrical - check
both ends of the nut. The 5/16" UNF bolts seem to have asymmetrical chamfers, but
these are closer to 90 degree. The outside tips have a ridge on them, so the outside
diameter of the countersunk hole should be the same as that measured across the flats
- 0.500" in this case.
Drilling an accurate clearance hole in the baseplate with a drill press and then sticking
a nut onto the flat surface is another option and this does give a high strength glue joint.
You can buy special nuts which have a large 45 degree chamfer on one end. These
should be excellent when used with holes shaped with a 90 degree multi fluted
countersink cutter.
You can also buy special nuts designed for insertion into sheet metal. They are longer
than ordinary nuts and are turned down to a small tube at one end. When used in sheet
metal, the turned down end is inserted through a hole in the sheet and the end is splayed
with a press or a ball hammer. However, they can also be pushed into a plain hole
drilled in say aluminum plate and secured with epoxy or loctite. You can use one at
both ends of a hole drilled through thick plate. This can provide a very precisely
aligned rigid mounting.
Another method of providing a thread in solft aluminum plate is to drill out a central
clearance hole for the bolt and then use a "special" counterbore cutter to drill a flat
bottomed hole slightly smaller than the outer diameter of the nut, to the length of the
nut. You then press in a nut into the hole, maybe adding epoxy or Loctite, using a vice
or a press. The six corners of the nut bed into the softer aluminum quite easily.
For epoxy to give a high strength joint, the surfaces need to conform closely and there
needs to ba an appreciable glue area. Epoxy will not stick a sharp edge to a conical
hole very well.
One thing that I have been doing is to drill the end of the vertical adjusting screws with
a centre drill. I then stick a stainless steel ball bearing into the V cup, with epoxy. The
diameter of the bearing is slightly less than the tap drill size for the thread used, i.e., use
a 5 mm ball for a 6 mm OD thread. This seems to give a contact which does not change
with time. The wide angle points which are sometimes used seem to "bed into" the
mounting plates and may wander a bit. The seismometer is mounted on 2" squares of
1/4" thick stainless steel bonded to a concrete floor.
I drill and tap the hole in the steel seismometer baseplate. I put a nut and a wavy
washer on the bolt, screw it into position and tension the nut. You can get wavy /
crinkle washers in phosphor bonze and stainless steel. They look like a very thin
ordinary washer but are bent to have three S shaped curves which act as a spring. A
dab of rubber contact adhesive will keep the nut from rotating as the suspension is
leveled and the wavy washer keeps the screw thread under tension.
Regards, Chris Chapman
Subject: Re: Timming on the Serial ADC board
From: "Larry Cochrane" lcochrane@..............
Date: Tue, 13 Jan 2004 00:04:52 -0800
Hi Arie,
Glad to see you're back. The GPS 25 is very similar to the their GPS 16 so
it may work directly with my A/D board. If it doesn't work I can always
modify the code to support this receiver.
To answer your question, yes you can feed in a 1 pulse per minute signal to
emulate the WWV signal.
Regards,
Larry Cochrane
Webtronics
----- Original Message -----
From: "Arie Verveer"
To:
Sent: Monday, January 12, 2004 5:42 AM
Subject: Timming on the Serial ADC board
> Hi all, I was looking at the specifications of "Larry's" Serial ADC board
> and noticed the "WWV" option. On the self I have a "Garmen GPS -25"
> evaluation board and was planning to make a circuit to mimic the
> "WWV" minute tone and feed this into the board. Has anyone done
> anything similar ?
>
> Also is it possible to feed a 600 ms pulse into the Serial ADC board
> as you can do with the ISA A/D board? Basically I want to use what
> I've got on hand other than purchasing a new "Garmen 16" GPS.
>
>
> Cheers
> Arie
>
>
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: ebay auction
From: BOB BARNS royb1@...........
Date: Mon, 19 Jan 2004 09:45:13 -0500
Hi gang,
An auction on ebay--looks attractive.
sprengnether MEQ800 seismograph Item number: 3268218007
ends 1/25
Bob
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: great seismometer!
From: BOB BARNS royb1@...........
Date: Mon, 26 Jan 2004 10:13:06 -0500
Hi gang,
An ebay auction--
sprengnether long period seismograph sensor Item number: 3269963085
ends 2/1.
Looks like rare opportunity.
Bob
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Anther STM-8 question
From: "Larry Conklin" lconklin@............
Date: Fri, 30 Jan 2004 11:12:02 -0500
I am starting to collect materials for a vertical seismo based on the STM-8
design. I have a rather small (7") speaker that I am considering for using
for the magnet and feedback coil, but I'm wondering if the magnet is strong
enough. Can anybody give me some insight into how big a magnet is needed or
whether I would have to make adjustments elsewhere in the design to
compensate for a smaller magnet?
Larry Conklin
Liverpool, NY
lconklin@............
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Anther STM-8 question
From: "kpayea" kpayea@...........
Date: Fri, 30 Jan 2004 08:44:55 -0800
The one clue we can get from STM's web page is buried in one of the
documents:
"...3. The feedback transducer (which was the moving coil velocity sensor of
the basic seismometer) has a low DC resistance but a very high force
constant (Newtons/Ampere), of the order of 10x the mass (in kg). ..."
I think that in one of his e-mails, Sean-Thomas mentioned a simple way to
measure this with your candidate speaker. It went something like this:
1. Set the speaker on the bench with the magnet down.
2. Measure the position of the center dome.
3. Set a known mass on the center dome.
4. Put a current into the voice coil, and record how much current it takes
to return the center dome
of the speaker to it's original position.
I think I used a 9V battery in series with a 10K pot, a meter, and the voice
coil.
Since you just need to return the cone to it's original position, no
expensive measurement tools are needed. Just rig up some kind of pointer.
The only important things are a known mass and a decent ammeter.
His original speaker was an 8" woofer from Radio Shack. I'm sure it was not
particularly hefty. A modern 6" woofer would probably have a higher force
constant.
Good Luck,
Keith
Keith Payea
Bryant Labs
kpayea@..............
www.bryantlabs.net
(707) 566-8935
----- Original Message -----
From: "Larry Conklin"
To: "PSN List"
Sent: Friday, January 30, 2004 8:12 AM
Subject: Anther STM-8 question
I am starting to collect materials for a vertical seismo based on the STM-8
design. I have a rather small (7") speaker that I am considering for using
for the magnet and feedback coil, but I'm wondering if the magnet is strong
enough. Can anybody give me some insight into how big a magnet is needed or
whether I would have to make adjustments elsewhere in the design to
compensate for a smaller magnet?
Larry Conklin
Liverpool, NY
lconklin@............
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Anther STM-8 question
From: "Larry Conklin" lconklin@............
Date: Fri, 30 Jan 2004 15:45:38 -0500
Many thanks for the tip Kieth.
Larry
----- Original Message -----
From: "kpayea"
To:
Cc:
Sent: Friday, January 30, 2004 11:44 AM
Subject: Re: Anther STM-8 question
> The one clue we can get from STM's web page is buried in one of the
> documents:
>
> "...3. The feedback transducer (which was the moving coil velocity sensor
of
> the basic seismometer) has a low DC resistance but a very high force
> constant (Newtons/Ampere), of the order of 10x the mass (in kg). ..."
>
> I think that in one of his e-mails, Sean-Thomas mentioned a simple way to
> measure this with your candidate speaker. It went something like this:
>
> 1. Set the speaker on the bench with the magnet down.
> 2. Measure the position of the center dome.
> 3. Set a known mass on the center dome.
> 4. Put a current into the voice coil, and record how much current it
takes
> to return the center dome
> of the speaker to it's original position.
>
> I think I used a 9V battery in series with a 10K pot, a meter, and the
voice
> coil.
>
> Since you just need to return the cone to it's original position, no
> expensive measurement tools are needed. Just rig up some kind of pointer.
> The only important things are a known mass and a decent ammeter.
>
> His original speaker was an 8" woofer from Radio Shack. I'm sure it was
not
> particularly hefty. A modern 6" woofer would probably have a higher force
> constant.
>
> Good Luck,
>
> Keith
>
> Keith Payea
> Bryant Labs
> kpayea@..............
> www.bryantlabs.net
> (707) 566-8935
> ----- Original Message -----
> From: "Larry Conklin"
> To: "PSN List"
> Sent: Friday, January 30, 2004 8:12 AM
> Subject: Anther STM-8 question
>
>
> I am starting to collect materials for a vertical seismo based on the
STM-8
> design. I have a rather small (7") speaker that I am considering for
using
> for the magnet and feedback coil, but I'm wondering if the magnet is
strong
> enough. Can anybody give me some insight into how big a magnet is needed
or
> whether I would have to make adjustments elsewhere in the design to
> compensate for a smaller magnet?
>
> Larry Conklin
> Liverpool, NY
> lconklin@............
>
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Another STM-8 question
From: "Meredith Lamb" meredithlamb@.............
Date: Wed, 4 Feb 2004 22:08:28 -0700
(This is a forwarded email reply from Chris Chapman)
I am starting to collect materials for a vertical seismo based on the STM-8 design. I have a rather small (7") speaker that I am considering for using for the magnet and feedback coil, but I'm wondering if the magnet is strong enough. Can anybody give me some insight into how big a magnet is needed or whether I would have to make adjustments elsewhere in the design to compensate for a smaller magnet?
Larry Conklin
Liverpool, NY
lconklin@............
Hi Larry,
This 'bit of string' sounds quite a bit too short! But it depends on how much mass you are planning to use. Check on the values given in Sean's description? The usual speaker systems use external Alnico cylinder magnets with a pole piece of 1.0" to 1.5" dia., maybe 4" outside diameter. The original speakers were 12" to 15" dia or even larger. You can measure the push well enough with one of the small 100 gm electronic scales, or by lifting a coin vertically. The cheaper speakers use Ferrite magnets, which were much more bulky, have lower fields, high stray fields and are much more temperature dependant.
One of the problems with speaker magnet systems is that the space for the coil only allows a few thou radial clearance. Ideally, you would find construction / setup much easier if you could turn out the pole gap a bit on a lathe to give maybe 15 thou clearance, inside and outside. The older speakers were bolted together, which made them easy to disassemble. Turned pole faces need a coat of rust resistant priming paint / electro-plating. The central column and the backplate of a speaker are usually one item. 16 ohm speakers are preferable, if you can get them.
Another alternative is to use four rectangular NdFeB magnets, maybe 5/16" to 1/2" thick, mounted on two vertical mild steel backing plates held apart with soft iron spacers. You then wind yourself a rectangular flat coil to fit in the central pole gap. The movement is parallel to the pole gap. www.Wondermagnet.com sometimes have magnet pairs already mounted onto a mild steel backing plate, Ref 0031. They also sell magnet wire. It is easy to visually check the magnet to pole face clearance in flat systems.
It is also quite possible to use 1"~1.5" dia NdFeB disk magnets as the centre column and add a circular end polepiece, a circular backing plate and a mild steel outer tube. It very much depends on what you can make / have made. I have used magnet columns about 1" long - two 1/2" thick magnets. I make the former out of 3.5 thou Al foil with a layer of tissue paper insulation, stuck onto an 1/8" Al end disk with air holes in it. I first machine a wood former, then dip it in candle wax, turn it down to size and mount up the end plate and the foil tube with epoxy. You then wind and varnish the coil. You warm the wax with a hair dryer and slide off the finished coil.
Regards,
Chris Chapman
(This is a forwarded email reply from Chris Chapman)
I am starting to collect materials for a vertical seismo based on the STM-8 design. I have a rather small (7") speaker that I am considering for using for the magnet and feedback coil, but I'm wondering if the magnet is strong enough. Can anybody give me some insight into how big a magnet is needed or whether I would have to make adjustments elsewhere in the design to compensate for a smaller magnet?
Larry Conklin
Liverpool, NY
lconklin@............
Hi Larry,
This 'bit of string' sounds quite a bit too short! But it depends on how much mass you are planning to use. Check on the values given in Sean's description? The usual speaker systems use external Alnico cylinder magnets with a pole piece of 1.0" to 1.5" dia., maybe 4" outside diameter. The original speakers were 12" to 15" dia or even larger. You can measure the push well enough with one of the small 100 gm electronic scales, or by lifting a coin vertically. The cheaper speakers use Ferrite magnets, which were much more bulky, have lower fields, high stray fields and are much more temperature dependant.
One of the problems with speaker magnet systems is that the space for the coil only allows a few thou radial clearance. Ideally, you would find construction / setup much easier if you could turn out the pole gap a bit on a lathe to give maybe 15 thou clearance, inside and outside. The olde
r speakers were bolted together, which made them easy to disassemble. Turned pole faces need a coat of rust resistant priming paint / electro-plating. The central column and the backplate of a speaker are usually one item. 16 ohm speakers are preferable, if you can get them.
Another alternative is to use four rectangular NdFeB magnets, maybe 5/16" to 1/2" thick, mounted on two vertical mild steel backing plates held apart with soft iron spacers. You then wind yourself a rectangular flat coil to fit in the central pole gap. The movement is parallel to the pole gap. www.Wondermagnet.com sometimes have magnet pairs already mounted onto a mild steel backing plate, Ref 0031. They also sell magnet wire. It is easy to visually check the magnet to pole face clearance in flat systems.
It is also quite possible to use 1"~1.5" dia NdFeB disk magnets as the centre column and add a circular end polepiece, a circular backing plate and a mild s
teel outer tube. It very much depends on what you can make / have made. I have used magnet columns about 1" long - two 1/2" thick magnets. I make the former out of 3.5 thou Al foil with a layer of tissue paper insulation, stuck onto an 1/8" Al end disk with air holes in it. I first machine a wood former, then dip it in candle wax, turn it down to size and mount up the end plate and the foil tube with epoxy. You then wind and varnish the coil. You warm the wax with a hair dryer and slide off the finished coil.
Regards,
Chris Chapman
Subject: Re: Another STM-8 question
From: "Larry Conklin" lconklin@............
Date: Thu, 5 Feb 2004 17:18:06 -0500
Chris,
Thanks for the info. Kieth Payea suggested a simple test that I can run =
to evaluate the adequacy of the speaker magnet that I have. If it does =
prove to be too wimpy, I appreciate your suggestions for alternatives.
Larry
----- Original Message -----=20
From: Meredith Lamb=20
To: psn-l=20
Sent: Thursday, February 05, 2004 12:08 AM
Subject: Re: Another STM-8 question
(This is a forwarded email reply from Chris Chapman)
I am starting to collect materials for a vertical seismo based on the =
STM-8 design. I have a rather small (7") speaker that I am considering =
for using for the magnet and feedback coil, but I'm wondering if the =
magnet is strong enough. Can anybody give me some insight into how big =
a magnet is needed or whether I would have to make adjustments =
elsewhere in the design to compensate for a smaller magnet?
Larry Conklin
Liverpool, NY
lconklin@............
Hi Larry,
This 'bit of string' sounds quite a bit too short! But it =
depends on how much mass you are planning to use. Check on the values =
given in Sean's description? The usual speaker systems use external =
Alnico cylinder magnets with a pole piece of 1.0" to 1.5" dia., maybe 4" =
outside diameter. The original speakers were 12" to 15" dia or even =
larger. You can measure the push well enough with one of the small 100 =
gm electronic scales, or by lifting a coin vertically. The cheaper =
speakers use Ferrite magnets, which were much more bulky, have lower =
fields, high stray fields and are much more temperature dependant.=20
One of the problems with speaker magnet systems is that the =
space for the coil only allows a few thou radial clearance. Ideally, you =
would find construction / setup much easier if you could turn out the =
pole gap a bit on a lathe to give maybe 15 thou clear! ance, inside and =
outside. The older speakers were bolted together, which made them easy =
to disassemble. Turned pole faces need a coat of rust resistant priming =
paint / electro-plating. The central column and the backplate of a =
speaker are usually one item. 16 ohm speakers are preferable, if you can =
get them.
Another alternative is to use four rectangular NdFeB magnets, =
maybe 5/16" to 1/2" thick, mounted on two vertical mild steel backing =
plates held apart with soft iron spacers. You then wind yourself a =
rectangular flat coil to fit in the central pole gap. The movement is =
parallel to the pole gap. www.Wondermagnet.com sometimes have magnet =
pairs already mounted onto a mild steel backing plate, Ref 0031. They =
also sell magnet wire. It is easy to visually check the magnet to pole =
face clearance in flat systems.
It is also quite possible to use 1"~1.5" dia NdFeB disk magnets =
as the centre column an! d add a circular end polepiece, a circular =
backing plate and a mild st eel outer tube. It very much depends on what =
you can make / have made. I have used magnet columns about 1" long - two =
1/2" thick magnets. I make the former out of 3.5 thou Al foil with a =
layer of tissue paper insulation, stuck onto an 1/8" Al end disk with =
air holes in it. I first machine a wood former, then dip it in candle =
wax, turn it down to size and mount up the end plate and the foil tube =
with epoxy. You then wind and varnish the coil. You warm the wax with a =
hair dryer and slide off the finished coil.
Regards,
Chris Chapman=20
Chris,
Thanks for the info. Kieth Payea suggested =
a simple=20
test that I can run to evaluate the adequacy of the speaker magnet that =
I=20
have. If it does prove to be too wimpy, I appreciate your =
suggestions for=20
alternatives.
Larry
----- Original Message -----
From:=20
Meredith Lamb
Sent: Thursday, February 05, =
2004 12:08=20
AM
Subject: Re: Another STM-8 =
question
(This is a forwarded email reply from Chris Chapman)
I am starting to collect materials for a vertical seismo based on =
the=20
STM-8 design. I have a rather small (7") speaker that I am =
considering=20
for using for the magnet and feedback coil, but I'm wondering if =
the=20
magnet is strong enough. Can anybody give me some insight into =
how big a=20
magnet is needed or whether I would have to make adjustments =
elsewhere=20
in the design to compensate for a smaller magnet?
Larry=20
Conklin
Liverpool, NY
lconklin@............
Hi =
Larry,
=20
This 'bit of string' sounds quite a bit too short! But it depends on =
how much=20
mass you are planning to use. Check on the values given in Sean's =
description?=20
The usual speaker systems use external Alnico cylinder magnets with a =
pole=20
piece of 1.0" to 1.5" dia., maybe 4" outside diameter. The =
original=20
speakers were 12" to 15" dia or even larger. You can measure the push =
well=20
enough with one of the small 100 gm electronic scales, or by lifting a =
coin=20
vertically. The cheaper speakers use Ferrite magnets, which were much =
more=20
bulky, have lower fields, high stray fields and are much more =
temperature=20
dependant.
One of the =
problems with=20
speaker magnet systems is that the space for the coil only allows a =
few thou=20
radial clearance. Ideally, you would find construction / setup much =
easier if=20
you could turn out the pole gap a bit on a lathe to give maybe 15 thou =
clear!=20
ance, inside and outside. The older speakers were bolted together, =
which made=20
them easy to disassemble. Turned pole faces need a coat of rust =
resistant=20
priming paint / electro-plating. The central column and the backplate =
of a=20
speaker are usually one item. 16 ohm speakers are preferable, if you =
can get=20
them.
Another alternative is =
to use=20
four rectangular NdFeB magnets, maybe 5/16" to 1/2" thick, mounted on =
two=20
vertical mild steel backing plates held apart with soft iron spacers. =
You then=20
wind yourself a rectangular flat coil to fit in the central pole gap. =
The=20
movement is parallel to the pole gap. www.Wondermagnet.com sometimes =
have=20
magnet pairs already mounted onto a mild steel backing plate, Ref =
0031. They=20
also sell magnet wire. It is easy to visually check the magnet to pole =
face=20
clearance in flat systems.
It =
is also=20
quite possible to use 1"~1.5" dia NdFeB disk magnets as the centre =
column an!=20
d add a circular end polepiece, a circular backing plate and a mild st =
eel=20
outer tube. It very much depends on what you can make / have made. I =
have used=20
magnet columns about 1" long - two 1/2" thick magnets. I make the =
former out=20
of 3.5 thou Al foil with a layer of tissue paper insulation, stuck =
onto an=20
1/8" Al end disk with air holes in it. I first machine a wood former, =
then dip=20
it in candle wax, turn it down to size and mount up the end plate and =
the foil=20
tube with epoxy. You then wind and varnish the coil. You warm the wax =
with a=20
hair dryer and slide off the finished=20
coil.
=20
Regards,
Chris Chapman=20
Subject: Re: Another STM-8 question
From: "Barry" gbl@.......
Date: Thu, 5 Feb 2004 18:40:15 -0800
Hi Larry
I've made about 6-7 magnet/coil assemblies for the verticals I have and =
I also had problems with speaker magnets(12" radio shack woofers) and =
their clearances. I used Sean Thomas' coil construction description with =
magnets purchased from Mcmaster. They work well with the coil =
construction description STM describes. I used a homemade balance beam =
with razor blade fulcrum to determine the coil factor (G).
Regards
Barry
----- Original Message -----=20
From: Larry Conklin=20
To: psn-l@.................
Sent: Thursday, February 05, 2004 2:18 PM
Subject: Re: Another STM-8 question
Chris,
Thanks for the info. Kieth Payea suggested a simple test that I can =
run to evaluate the adequacy of the speaker magnet that I have. If it =
does prove to be too wimpy, I appreciate your suggestions for =
alternatives.
Larry
----- Original Message -----=20
From: Meredith Lamb=20
To: psn-l=20
Sent: Thursday, February 05, 2004 12:08 AM
Subject: Re: Another STM-8 question
(This is a forwarded email reply from Chris Chapman)
I am starting to collect materials for a vertical seismo based on =
the STM-8 design. I have a rather small (7") speaker that I am =
considering for using for the magnet and feedback coil, but I'm =
wondering if the magnet is strong enough. Can anybody give me some =
insight into how big a magnet is needed or whether I would have to make =
adjustments elsewhere in the design to compensate for a smaller magnet?
Larry Conklin
Liverpool, NY
lconklin@............
Hi Larry,
This 'bit of string' sounds quite a bit too short! But it =
depends on how much mass you are planning to use. Check on the values =
given in Sean's description? The usual speaker systems use external =
Alnico cylinder magnets with a pole piece of 1.0" to 1.5" dia., maybe 4" =
outside diameter. The original speakers were 12" to 15" dia or even =
larger. You can measure the push well enough with one of the small 100 =
gm electronic scales, or by lifting a coin vertically. The cheaper =
speakers use Ferrite magnets, which were much more bulky, have lower =
fields, high stray fields and are much more temperature dependant.=20
One of the problems with speaker magnet systems is that the =
space for the coil only allows a few thou radial clearance. Ideally, you =
would find construction / setup much easier if you could turn out the =
pole gap a bit on a lathe to give maybe 15 thou clear! ance, inside and =
outside. The older speakers were bolted together, which made them easy =
to disassemble. Turned pole faces need a coat of rust resistant priming =
paint / electro-plating. The central column and the backplate of a =
speaker are usually one item. 16 ohm speakers are preferable, if you can =
get them.
Another alternative is to use four rectangular NdFeB magnets, =
maybe 5/16" to 1/2" thick, mounted on two vertical mild steel backing =
plates held apart with soft iron spacers. You then wind yourself a =
rectangular flat coil to fit in the central pole gap. The movement is =
parallel to the pole gap. www.Wondermagnet.com sometimes have magnet =
pairs already mounted onto a mild steel backing plate, Ref 0031. They =
also sell magnet wire. It is easy to visually check the magnet to pole =
face clearance in flat systems.
It is also quite possible to use 1"~1.5" dia NdFeB disk =
magnets as the centre column an! d add a circular end polepiece, a =
circular backing plate and a mild st eel outer tube. It very much =
depends on what you can make / have made. I have used magnet columns =
about 1" long - two 1/2" thick magnets. I make the former out of 3.5 =
thou Al foil with a layer of tissue paper insulation, stuck onto an 1/8" =
Al end disk with air holes in it. I first machine a wood former, then =
dip it in candle wax, turn it down to size and mount up the end plate =
and the foil tube with epoxy. You then wind and varnish the coil. You =
warm the wax with a hair dryer and slide off the finished coil.
Regards,
Chris Chapman=20
Hi Larry
I've made about 6-7 magnet/coil assemblies for =
the=20
verticals I have and I also had problems with speaker magnets(12" =
radio=20
shack woofers) and their clearances. I used Sean Thomas' coil =
construction=20
description with magnets purchased from Mcmaster. They work well with =
the coil=20
construction description STM describes. I used a homemade balance =
beam with=20
razor blade fulcrum to determine the coil factor (G).
Regards
Barry
----- Original Message -----
From:=20
Larry=20
Conklin
Sent: Thursday, February 05, =
2004 2:18=20
PM
Subject: Re: Another STM-8 =
question
Chris,
Thanks for the info. Kieth Payea =
suggested a=20
simple test that I can run to evaluate the adequacy of the speaker =
magnet that=20
I have. If it does prove to be too wimpy, I appreciate your =
suggestions=20
for alternatives.
Larry
----- Original Message -----
From:=20
Meredith Lamb
Sent: Thursday, February 05, =
2004 12:08=20
AM
Subject: Re: Another STM-8=20
question
(This is a forwarded email reply from Chris Chapman)
I am starting to collect materials for a vertical seismo based =
on the=20
STM-8 design. I have a rather small (7") speaker that I am =
considering=20
for using for the magnet and feedback coil, but I'm wondering =
if the=20
magnet is strong enough. Can anybody give me some insight into =
how big=20
a magnet is needed or whether I would have to make adjustments =
elsewhere in the design to compensate for a smaller =
magnet?
Larry=20
Conklin
Liverpool, NY
lconklin@............
Hi =
Larry,
=20
This 'bit of string' sounds quite a bit too short! But it depends on =
how=20
much mass you are planning to use. Check on the values given in =
Sean's=20
description? The usual speaker systems use external Alnico cylinder =
magnets=20
with a pole piece of 1.0" to 1.5" dia., maybe 4" outside =
diameter. The=20
original speakers were 12" to 15" dia or even larger. You can =
measure the=20
push well enough with one of the small 100 gm electronic scales, or =
by=20
lifting a coin vertically. The cheaper speakers use Ferrite magnets, =
which=20
were much more bulky, have lower fields, high stray fields and are =
much more=20
temperature dependant.
One =
of the=20
problems with speaker magnet systems is that the space for the coil =
only=20
allows a few thou radial clearance. Ideally, you would find =
construction /=20
setup much easier if you could turn out the pole gap a bit on a =
lathe to=20
give maybe 15 thou clear! ance, inside and outside. The older =
speakers were=20
bolted together, which made them easy to disassemble. Turned pole =
faces need=20
a coat of rust resistant priming paint / electro-plating. The =
central column=20
and the backplate of a speaker are usually one item. 16 ohm speakers =
are=20
preferable, if you can get =
them.
=20
Another alternative is to use four rectangular NdFeB magnets, maybe =
5/16" to=20
1/2" thick, mounted on two vertical mild steel backing plates held =
apart=20
with soft iron spacers. You then wind yourself a rectangular flat =
coil to=20
fit in the central pole gap. The movement is parallel to the pole =
gap.=20
www.Wondermagnet.com sometimes have magnet pairs already mounted =
onto a mild=20
steel backing plate, Ref 0031. They also sell magnet wire. It is =
easy to=20
visually check the magnet to pole face clearance in flat=20
systems.
It is also quite =
possible=20
to use 1"~1.5" dia NdFeB disk magnets as the centre column an! d add =
a=20
circular end polepiece, a circular backing plate and a mild st eel =
outer=20
tube. It very much depends on what you can make / have made. I have =
used=20
magnet columns about 1" long - two 1/2" thick magnets. I make the =
former out=20
of 3.5 thou Al foil with a layer of tissue paper insulation, stuck =
onto an=20
1/8" Al end disk with air holes in it. I first machine a wood =
former, then=20
dip it in candle wax, turn it down to size and mount up the end =
plate and=20
the foil tube with epoxy. You then wind and varnish the coil. You =
warm the=20
wax with a hair dryer and slide off the finished=20
coil.
=20
Regards,
Chris Chapman=20
Subject: 2 ebay auctions
From: BOB BARNS royb1@...........
Date: Mon, 09 Feb 2004 09:52:33 -0500
Hi gang,
Ebay has two items:
BISON Model 1570-C Complete Seismograph Kit
Fully Functional Working Condition!
ends 2/15
WORKING SEISMOGRAPH SEISMIC GEOPHONE Item number: 3273117293
ends 2/15
Bob
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Different pendulum design
From: John or Jan Lahr johnjan@........
Date: Mon, 09 Feb 2004 08:51:16 -0700
I've built a prototype horizontal-pendulum seismic sensor using a design that
Brady Romberg, a School of Mines student, came up with. This still needs
a lot of work, but I thought the mechanical design was quite interesting.
I've posted a seismogram and some photos here:
http://jclahr.com/science/psn/romberg/
The weakness in this design is the vertical rod and it's attachment to the
horizontal plate. I think flexure in the rod and/or attachment is what limits
the period to about 2 seconds. Perhaps the mass needs to hang from a V-
shaped support rather than a single rod.
Cheers,
John
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: Different pendulum design
From: "John D Nelson" jnelson@.................
Date: Mon, 9 Feb 2004 11:14:58 -0600
It seems to me that there might be considerable friction losses in the
supporting points because of the weight that they bear-could this be a
factor?
-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@...............
On Behalf Of John or Jan Lahr
Sent: Monday, February 09, 2004 9:51 AM
To: psn-l@..............
Cc: bromberg@.........
Subject: Different pendulum design
I've built a prototype horizontal-pendulum seismic sensor using a design
that
Brady Romberg, a School of Mines student, came up with. This still
needs
a lot of work, but I thought the mechanical design was quite
interesting.
I've posted a seismogram and some photos here:
http://jclahr.com/science/psn/romberg/
The weakness in this design is the vertical rod and it's attachment to
the
horizontal plate. I think flexure in the rod and/or attachment is what
limits
the period to about 2 seconds. Perhaps the mass needs to hang from a V-
shaped support rather than a single rod.
Cheers,
John
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: Different pendulum design
From: John or Jan Lahr johnjan@........
Date: Mon, 09 Feb 2004 12:58:09 -0700
Yes, very possibly. I haven't come up with a better support system.
John
At 10:14 AM 2/9/2004, John Nelson wrote:
>It seems to me that there might be considerable friction losses in the
>supporting points because of the weight that they bear-could this be a
>factor?
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Different pendulum design
From: "David H. Youden" dyouden@.............
Date: Tue, 10 Feb 2004 10:56:07 -0500
John,
That looks like an interesting design that has failed in the execution.
You should really try it again, but next time try using the extruded
aluminum shapes that you can buy at any of the Home Depot type stores.
They are relatively inexpensive and you can build quite rigid structures
using square tubes and such. To make good flexure hinges use stainless
steel shim stock, which comes in 1/2" wide strips in thicknesses from
..001" on up. A quick calculation will show that a 1/2 inch wide piece
of .001 shim will support a sizeable load in tension. At least 10 pounds
per flexure, and probably 20 pounds, if you can clamp it well enough.
Rigidity is very important for a structure such as you and Brady have
devised, so don't skimp on materials.
Keep up the good work.
Dave...
John or Jan Lahr wrote:
> I've built a prototype horizontal-pendulum seismic sensor using a
> design that
> Brady Romberg, a School of Mines student, came up with. This still needs
> a lot of work, but I thought the mechanical design was quite interesting.
>
> I've posted a seismogram and some photos here:
> http://jclahr.com/science/psn/romberg/
>
> The weakness in this design is the vertical rod and it's attachment to
> the
> horizontal plate. I think flexure in the rod and/or attachment is
> what limits
> the period to about 2 seconds. Perhaps the mass needs to hang from a V-
> shaped support rather than a single rod.
>
> Cheers,
> John
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with the body of
> the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Digest from 02/09/2004 00:01:08
From: "Roger Sparks" rsparks@..........
Date: Tue, 10 Feb 2004 09:51:46 -0800
This is a variation of an inverted pendulum design.
Using two verticals, it has two stable points which are horizontally
displaced. The displacement becomes more obvious as the supporting sides
are made more vertical to increase the pendulum period, but it is present no
matter what vertical angles are used in this design.
An observer can see that this is true by observing that for horizontal
motion to the left (from centered position), the left side of the tee will
raise less than the right hand falls. As a result, the center (which is the
support for the mass) will have a small drop in height. The same thing is
true for horizontal shifts to the right.
The drop in height of the tee center is countered by an increase in height
of the pendulum mass as it begins motion. Unfortunately, the rise of
the pendulum as it moves from center (lowest point) is slower than the drop
from the change in tee height when moving off center so it can not
completely overcome (prevent or compensate) the drop of the support center.
This is no longer correct if the pendulum length is made so long that the
pendulum
motion arc is below the lower pivot points of the sides, which offers a way
to make the device have only one stable point.
In other words, try raising the lower side pivot points while leaving the
cross
plate height the same. Make the sides shorter and more nearly vertical.
I think that will lengthen the period and cure the bistable problem.
Thanks for making this interesting design available for consideration,
Roger
> .------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
> | Message 2 |
> '------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
> Subject: Different pendulum design
> From: John or Jan Lahr
> Date: Mon, 09 Feb 2004 08:51:16 -0700
>
> I've built a prototype horizontal-pendulum seismic sensor using a design
that
> Brady Romberg, a School of Mines student, came up with. This still needs
> a lot of work, but I thought the mechanical design was quite interesting.
>
> I've posted a seismogram and some photos here:
> http://jclahr.com/science/psn/romberg/
>
> The weakness in this design is the vertical rod and it's attachment to the
> horizontal plate. I think flexure in the rod and/or attachment is what
limits
> the period to about 2 seconds. Perhaps the mass needs to hang from a V-
> shaped support rather than a single rod.
>
> Cheers,
> John
>
>
>
> .------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
> | Message 3 |
> '------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
> Subject: RE: Different pendulum design
> From: "John D Nelson"
> Date: Mon, 9 Feb 2004 11:14:58 -0600
>
> It seems to me that there might be considerable friction losses in the
> supporting points because of the weight that they bear-could this be a
> factor?
>
> -----Original Message-----
> From: psn-l-request@.............. [mailto:psn-l-request@...............
> On Behalf Of John or Jan Lahr
> Sent: Monday, February 09, 2004 9:51 AM
> To: psn-l@..............
> Cc: bromberg@.........
> Subject: Different pendulum design
>
> I've built a prototype horizontal-pendulum seismic sensor using a design
> that
> Brady Romberg, a School of Mines student, came up with. This still
> needs
> a lot of work, but I thought the mechanical design was quite
> interesting.
>
> I've posted a seismogram and some photos here:
> http://jclahr.com/science/psn/romberg/
>
> The weakness in this design is the vertical rod and it's attachment to
> the
> horizontal plate. I think flexure in the rod and/or attachment is what
> limits
> the period to about 2 seconds. Perhaps the mass needs to hang from a V-
> shaped support rather than a single rod.
>
> Cheers,
> John
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with=20
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>
>
> .------ ------ ------ ------ ------ ------ ------ ------ ------ ------.
> | Message 4 |
> '------ ------ ------ ------ ------ ------ ------ ------ ------ ------'
> Subject: RE: Different pendulum design
> From: John or Jan Lahr
> Date: Mon, 09 Feb 2004 12:58:09 -0700
>
> Yes, very possibly. I haven't come up with a better support system.
>
> John
>
> At 10:14 AM 2/9/2004, John Nelson wrote:
>
> >It seems to me that there might be considerable friction losses in the
> >supporting points because of the weight that they bear-could this be a
> >factor?
>
>
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-DIGEST-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: Digest from 02/09/2004 00:01:08
From: "John D Nelson" jnelson@.................
Date: Tue, 10 Feb 2004 13:34:48 -0600
Would raising the weight contribute to the period? Seems to me the
higher the weight, the shorter bar the weight is on, hence less
leverage, and the more unstable the structure becomes.
John Nelson
-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@...............
On Behalf Of Roger Sparks
Sent: Tuesday, February 10, 2004 11:52 AM
To: psn-l@..............
Subject: Re: Digest from 02/09/2004 00:01:08
This is a variation of an inverted pendulum design.
Using two verticals, it has two stable points which are horizontally
displaced. The displacement becomes more obvious as the supporting
sides
are made more vertical to increase the pendulum period, but it is
present no
matter what vertical angles are used in this design.
An observer can see that this is true by observing that for horizontal
motion to the left (from centered position), the left side of the tee
will
raise less than the right hand falls. As a result, the center (which is
the
support for the mass) will have a small drop in height. The same thing
is
true for horizontal shifts to the right.
The drop in height of the tee center is countered by an increase in
height
of the pendulum mass as it begins motion. Unfortunately, the rise of
the pendulum as it moves from center (lowest point) is slower than the
drop
from the change in tee height when moving off center so it can not
completely overcome (prevent or compensate) the drop of the support
center.
This is no longer correct if the pendulum length is made so long that
the
pendulum
motion arc is below the lower pivot points of the sides, which offers a
way
to make the device have only one stable point.
In other words, try raising the lower side pivot points while leaving
the
cross
plate height the same. Make the sides shorter and more nearly vertical.
I think that will lengthen the period and cure the bistable problem.
Thanks for making this interesting design available for consideration,
Roger
> .------ ------ ------ ------ ------ ------ ------ ------ ------
------.
> | Message 2
|
> '------ ------ ------ ------ ------ ------ ------ ------ ------
------'
> Subject: Different pendulum design
> From: John or Jan Lahr
> Date: Mon, 09 Feb 2004 08:51:16 -0700
>
> I've built a prototype horizontal-pendulum seismic sensor using a
design
that
> Brady Romberg, a School of Mines student, came up with. This still
needs
> a lot of work, but I thought the mechanical design was quite
interesting.
>
> I've posted a seismogram and some photos here:
> http://jclahr.com/science/psn/romberg/
>
> The weakness in this design is the vertical rod and it's attachment to
the
> horizontal plate. I think flexure in the rod and/or attachment is
what
limits
> the period to about 2 seconds. Perhaps the mass needs to hang from a
V-
> shaped support rather than a single rod.
>
> Cheers,
> John
>
>
>
> .------ ------ ------ ------ ------ ------ ------ ------ ------
------.
> | Message 3
|
> '------ ------ ------ ------ ------ ------ ------ ------ ------
------'
> Subject: RE: Different pendulum design
> From: "John D Nelson"
> Date: Mon, 9 Feb 2004 11:14:58 -0600
>
> It seems to me that there might be considerable friction losses in the
> supporting points because of the weight that they bear-could this be a
> factor?
>
> -----Original Message-----
> From: psn-l-request@..............
[mailto:psn-l-request@...............
> On Behalf Of John or Jan Lahr
> Sent: Monday, February 09, 2004 9:51 AM
> To: psn-l@..............
> Cc: bromberg@.........
> Subject: Different pendulum design
>
> I've built a prototype horizontal-pendulum seismic sensor using a
design
> that
> Brady Romberg, a School of Mines student, came up with. This still
> needs
> a lot of work, but I thought the mechanical design was quite
> interesting.
>
> I've posted a seismogram and some photos here:
> http://jclahr.com/science/psn/romberg/
>
> The weakness in this design is the vertical rod and it's attachment to
> the
> horizontal plate. I think flexure in the rod and/or attachment is
what
> limits
> the period to about 2 seconds. Perhaps the mass needs to hang from a
V-
> shaped support rather than a single rod.
>
> Cheers,
> John
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with=3D20
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
>
>
> .------ ------ ------ ------ ------ ------ ------ ------ ------
------.
> | Message 4
|
> '------ ------ ------ ------ ------ ------ ------ ------ ------
------'
> Subject: RE: Different pendulum design
> From: John or Jan Lahr
> Date: Mon, 09 Feb 2004 12:58:09 -0700
>
> Yes, very possibly. I haven't come up with a better support system.
>
> John
>
> At 10:14 AM 2/9/2004, John Nelson wrote:
>
> >It seems to me that there might be considerable friction losses in
the
> >supporting points because of the weight that they bear-could this be
a
> >factor?
>
>
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-DIGEST-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Different pendulum design
From: John or Jan Lahr johnjan@........
Date: Tue, 10 Feb 2004 15:59:10 -0700
At 11:42 AM 2/10/2004, you wrote:
Hi Chris,
Thanks for the feedback. The pivots are made from safety pin point
embedded in the
Plexiglas sheeting. They rest in dents in the aluminum and in dents in the
plastic.
All of the pivots are in compression. I think I'll try the "ball on plane"
joint next.
I think I need the weight to offset the weight of the sheets of
plastic. Maybe lighter
material would help to reduce their effect.
The coil is mounted as you suggest. The axis of symmetry is horizontal and
although the axis of symmetry moves in a only a slight arc, the coil does
rotate
during this movement, as it remains perpendicular to the threaded rod.
Cheers,
John
>Hi John,
>
> I suspect that the problem lies a) in the suspension of the
> plates, b) in the 'springyness' or hysteresis of this suspension and c)
> in the flexure of the pendulum threaded rod. I can't quite see how you
> have made your suspension joints. Three types of suspension give few
> problems: 1 flexing foils or wires, preferably crossed for rigidity, 2
> ball on plane, 3 circular cylinder crossed on circular cylinder. Point on
> plane types are just asking for trouble.
>
>
> >> Romberg-Style Horizontal Pendulum
>
> >> February 7, 2004. Mw 7.1This sensor is my first attempt to make the
> compact pendulum described
> here. I have
> not been able to obtain a period longer than 2 seconds, possibly due to
> slight flexure of central threaded rod that carries the lead
> weight. When adjusted for a longer period, the pendulum will drift to
> one side or the other and is stable at either extreme.
>
> You should be able to get a wide range of periods. I suspect that
> the suspension is being stabilised by the spring flexing and that this
> has a slightly different force law to the geometrical path relationship.
> This is a 'general case' of the folded pendulum type suspension.
> It is quite easy to get periods of over 45 sec with folded pendulum
> suspensions.
>
> >> The magnet/coil pickup is from a PC hard drive. It seems to have
> sufficient gain. One problem is that in this design the coil rotates as
> it moves back and forth so that the amount of free travel is quite limited.
>
> You would probably find it much more satisfactory if you suspended
> the coil with it's axis of symmetry horizontal, perpendicular to the
> plane of motion of the pendulum and in between horizontal magnet pairs. I
> doubt if you really need all that lead. Plan view:
>
> NNNNSSSS
> C--O--I--L <--- movement --->
> SSSSNNNN
>
> Regards,
>
> Chris Chapman
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Different pendulum design
From: Karl Cunningham karlc@..........
Date: Tue, 10 Feb 2004 17:54:04 -0800
John --
I haven't examined the geometry of this design in detail, but could it be
changed in a way to make it work upside down? If the two side plates were
hanging from a support above, they would be in tension and could be made
from something much much thinner. Perhaps even wire trusses that would
have rigidity in off-axis directions. The cross piece would still have to
be strong and thick. Or maybe the weight could be supported by more wire
trusses with a cross-piece to keep the junctions separated. One could let
the bending of the wires act as mostly-friction-free flexures.
The geometry would have to change in such a way that it still has a
positive period (negative period being unstable so that it falls to one
side and stays there). I'm not sure this is possible but maybe. The
support would have to attach very near to the center of mass. A bit like
the basket of a hot-air balloon.
// // // // //
____________________________________________________________
\ /
\ /
\ /
\ /
\ /
\ /
\ / wire trusses
\ / for angled
\ thicker strut / supports
+----------------------------+
\ /
\ /
\ /
\ /
\ -------- /
| |
|\ M / |
| |
--------
Karl Cunningham
--On Tuesday, February 10, 2004 3:59 PM -0700 John or Jan Lahr
wrote:
> At 11:42 AM 2/10/2004, you wrote:
>
> Hi Chris,
>
> Thanks for the feedback. The pivots are made from safety pin point
> embedded in the Plexiglas sheeting. They rest in dents in the aluminum
> and in dents in the plastic. All of the pivots are in compression. I
> think I'll try the "ball on plane" joint next.
>
> I think I need the weight to offset the weight of the sheets of plastic.
> Maybe lighter material would help to reduce their effect.
>
> The coil is mounted as you suggest. The axis of symmetry is horizontal
> and although the axis of symmetry moves in a only a slight arc, the coil
> does rotate during this movement, as it remains perpendicular to the
> threaded rod.
>
> Cheers,
> John
>
>
>
>> Hi John,
>>
>> I suspect that the problem lies a) in the suspension of the
>> plates, b) in the 'springyness' or hysteresis of this suspension and c)
>> in the flexure of the pendulum threaded rod. I can't quite see how you
>> have made your suspension joints. Three types of suspension give few
>> problems: 1 flexing foils or wires, preferably crossed for rigidity, 2
>> ball on plane, 3 circular cylinder crossed on circular cylinder. Point
>> on plane types are just asking for trouble.
>>
>>
>> >> Romberg-Style Horizontal Pendulum
>>
>> >> February 7, 2004. Mw 7.1This sensor is my first attempt to make the
>> compact pendulum described
>> here. I have
>> not been able to obtain a period longer than 2 seconds, possibly due to
>> slight flexure of central threaded rod that carries the lead
>> weight. When adjusted for a longer period, the pendulum will drift to
>> one side or the other and is stable at either extreme.
>>
>> You should be able to get a wide range of periods. I suspect that
>> the suspension is being stabilised by the spring flexing and that this
>> has a slightly different force law to the geometrical path relationship.
>> This is a 'general case' of the folded pendulum type suspension.
>> It is quite easy to get periods of over 45 sec with folded pendulum
>> suspensions.
>>
>> >> The magnet/coil pickup is from a PC hard drive. It seems to have
>> sufficient gain. One problem is that in this design the coil rotates as
>> it moves back and forth so that the amount of free travel is quite
>> limited.
>>
>> You would probably find it much more satisfactory if you
>> suspended the coil with it's axis of symmetry horizontal,
>> perpendicular to the plane of motion of the pendulum and in between
>> horizontal magnet pairs. I doubt if you really need all that lead. Plan
>> view:
>>
>> NNNNSSSS
>> C--O--I--L <--- movement --->
>> SSSSNNNN
>>
>> Regards,
>>
>> Chris Chapman
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with the body of
> the message (first line only): unsubscribe See
> http://www.seismicnet.com/maillist.html for more information.
Regards,
Karl Cunningham
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Theory of the Earth
From: John or Jan Lahr johnjan@........
Date: Wed, 25 Feb 2004 19:18:50 -0700
>
>Don Anderson's out of print book,Theory of the Earth, can now be freely
>accessed and downloaded from:
>
>http://caltechbook.library.caltech.edu/archive/00000014/
>
>Cheers,
>John
>
>
>
>##################################/ John C. Lahr
>#################################/ Emeritus Seismologist
>################################/ U.S. Geological Survey
>===========================/ Geologic Hazards Team, MS966
>##############################/ PO Box 25046
>#############################//##############################
>############################//###############################
> Denver, Colorado 80225-0046 /################################
> Phone: (303) 273-8596 /=============================
> Fax: (303) 273-8600 /##################################
> lahr@........ /###################################
>
>/####################################
> http://jclahr.com/science/
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Kinemetrics SS-1 Ranger Seismometer for sale on eBay
From: apsn apsn@...........
Date: Sat, 28 Feb 2004 09:48:49 -0900
Kinemetrics SS-1 Ranger Seismometer for sale on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3178602902&category=11737
This is a very good, very rugged 1 Hz seismometer.
Bob Hammond
PSN - Alaska
http://apsn.awcable.com
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Info on Sprengnether VS-1100
From: "David M Payne" asmcoder@...........
Date: Sat, 28 Feb 2004 19:33:45 -0600
Does anyone have documentation for a Sprengnether VS-1100 recorder? esp
geophone pin outs or info relating to such. It has a circular 10 pin
connector with a 3-4-3 configuration.
Thanks,
David
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Kinemetrics SS-1 Ranger Seismometer for sale on eBay
From: "P. Beenders" piet.beenders@.........
Date: Sun, 29 Feb 2004 23:19:09 +0100
Does anybody know if the adjustable range of the sensor is long enough to
make a long period sensor out of it ?
Piet Beenders
PSN - Roggel NL
www.peut.net / www.peutware.tk
----- Original Message -----
From: "apsn"
To:
Sent: Saturday, February 28, 2004 7:48 PM
Subject: Kinemetrics SS-1 Ranger Seismometer for sale on eBay
> Kinemetrics SS-1 Ranger Seismometer for sale on eBay:
>
>
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3178602902&category=11737
>
> This is a very good, very rugged 1 Hz seismometer.
>
> Bob Hammond
> PSN - Alaska
> http://apsn.awcable.com
>
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSN-L)
>
> To leave this list email PSN-L-REQUEST@.............. with
> the body of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Re: Kinemetrics SS-1 Ranger Seismometer for sale on eBay
From: apsn apsn@...........
Date: Sun, 29 Feb 2004 14:02:06 -0900
Piet,
No, this is a 1 Hz seismometer. See: http://www.kinemetrics.com/ss1.html
Bob Hammond
PSN - Alaska
http://apsn.awcable.com
At 01:19 PM 2/29/2004, you wrote:
>Does anybody know if the adjustable range of the sensor is long enough to
>make a long period sensor out of it ?
>
>Piet Beenders
>PSN - Roggel NL
>www.peut.net / www.peutware.tk
>
>
>----- Original Message -----
>From: "apsn"
>To:
>Sent: Saturday, February 28, 2004 7:48 PM
>Subject: Kinemetrics SS-1 Ranger Seismometer for sale on eBay
>
>
> > Kinemetrics SS-1 Ranger Seismometer for sale on eBay:
> >
> >
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3178602902&category=11737
> >
> > This is a very good, very rugged 1 Hz seismometer.
> >
> > Bob Hammond
> > PSN - Alaska
> > http://apsn.awcable.com
> >
> > __________________________________________________________
> >
> > Public Seismic Network Mailing List (PSN-L)
> >
> > To leave this list email PSN-L-REQUEST@.............. with
> > the body of the message (first line only): unsubscribe
> > See http://www.seismicnet.com/maillist.html for more information.
>
>__________________________________________________________
>
>Public Seismic Network Mailing List (PSN-L)
>
>To leave this list email PSN-L-REQUEST@.............. with
>the body of the message (first line only): unsubscribe
>See http://www.seismicnet.com/maillist.html for more information.
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: Kinemetrics SS-1 Ranger Seismometer for sale on eBay
From: "Doug Crice" dcrice@............
Date: Sun, 29 Feb 2004 15:03:28 -0800
No, the period can only be adjusted over a modest range around 1 Hz.
This is a good 1 Hz sensor, but I think the guy is trying to get too =
much
money.
Doug Crice
Geostuff http://www.georadar.com/geostuff.htm
12996 Somerset Drive phone 1-530-274-4445
Grass Valley, CA 95945 USA fax 1-530-274-4446
=20
-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... =
On
Behalf Of P. Beenders
Sent: Sunday, February 29, 2004 2:19 PM
To: psn-l@..............
Subject: Re: Kinemetrics SS-1 Ranger Seismometer for sale on eBay
Does anybody know if the adjustable range of the sensor is long enough =
to
make a long period sensor out of it ?
Piet Beenders
PSN - Roggel NL
www.peut.net / www.peutware.tk
> Kinemetrics SS-1 Ranger Seismometer for sale on eBay:
>
>
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3D3178602902&category=3D=
11737
>
> This is a very good, very rugged 1 Hz seismometer.
>
> Bob Hammond
> PSN - Alaska
> http://apsn.awcable.com
>
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: Fwd: new Wood-Anderson in Trieste
From: John or Jan Lahr johnjan@........
Date: Thu, 04 Mar 2004 18:04:39 -0700
The clever, position-sensing system described by Dario Slejko (see below)
may be of
some interest to amateurs as well. Note that the URL for Sitek
given on his
web site should be:
http://www.sitek.se/
Cheers,
John
Date:
Thu, 4 Mar 2004 09:21:41 +0100
To: boltuc@...................... perkins@.........
lahr@....................
benz@......... bellini@......... stucchi@...........
pierre-yves.bard@....................
j.bommer@.........
bruestle@.....................
hilmar.bungum@..........
nico@................... faeh@...................
mgarcia@............
ggrue@............... dmrosa2@...........
mcguire@............
rmwm@.......... stefan@...................
paolo@..................
From: Dario Slejko <dslejko@..............>
Subject: new Wood-Anderson in Trieste
Cc: fgentile@..............
X-Spam-Score: -9.1 () PWZIP2_PS,SEISMOLOGY_PS,SPAM_PHRASE_00_01
X-Scanned-By: MIMEDefang 2.30 (www . roaringpenguin . com /
mimedefang)
X-MIMETrack: Itemize by SMTP Server on gscodenh01/SERVER/USGS/DOI(Release
5.0.12HF345 | August
14, 2003) at 03/04/2004 01:22:01 AM,
Serialize
by POP3 Server on gscodenm05/SERVER/USGS/DOI(Release 5.0.12HF345
| August 14, 2003) at 03/04/2004 01:27:11 AM,
Serialize
complete at 03/04/2004 01:27:11 AM
Dear all,
a digital acquisition system for the Wood-Anderson seismometer has
been
designed in Trieste by by collegue Francesco Gentile
(fgentile@................ The system is now operating and you can
read
info about it at:
http://doga.ogs.trieste.it/doga/risk/woodanderson/index.html
Best regards,
Dario Slejko
--------------------------------------------------------------
Dario Slejko
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale
Borgo Grotta Gigante 42c, 34010 Sgonico (Trieste), Italy
tel. +39 040 2140248; fax +39 040 327307
e-mail dslejko@..............
--------------------------------------------------------------
##################################/
John C. Lahr
#################################/ Emeritus Seismologist
################################/ U.S. Geological Survey
===========================/ Geologic Hazards Team, MS966
##############################/ PO Box 25046
#############################//##############################
############################//###############################
Denver, Colorado 80225-0046
/################################
Phone: (303) 273-8596 /=============================
Fax: (303) 273-8600 /##################################
lahr@........ /###################################
/####################################
http://jclahr.com/science/
Subject: Re: new Wood-Anderson in Trieste
From: John or Jan Lahr johnjan@........
Date: Fri, 05 Mar 2004 21:02:55 -0700
I checked on the price of the 1L20. It's $335
from On-Trak Photonics, Inc, Lake Forest, CA.
This is not an inexpensive solution, at least at this time!
John
To: psn-l@..............
From: John or Jan Lahr <johnjan@........>
Subject: Fwd: new Wood-Anderson in Trieste
The clever, position-sensing system described by Dario Slejko (see below)
may be of
some interest to amateurs as well. Note that the URL for Sitek
given on his
web site should be:
http://www.sitek.se/
Cheers,
John
From:
Dario Slejko <dslejko@..............>
Dear all,
a digital acquisition system for the Wood-Anderson seismometer has
been
designed in Trieste by by collegue Francesco Gentile
(fgentile@................ The system is now operating and you can
read
info about it at:
http://doga.ogs.trieste.it/doga/risk/woodanderson/index.html
Best regards,
Dario Slejko
--------------------------------------------------------------
Dario Slejko
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale
Borgo Grotta Gigante 42c, 34010 Sgonico (Trieste), Italy
tel. +39 040 2140248; fax +39 040 327307
e-mail dslejko@..............
--------------------------------------------------------------
Subject: Re: new Wood-Anderson in Trieste
From: "Meredith Lamb" meredithlamb@.............
Date: Mon, 8 Mar 2004 16:16:13 -0700
Hi all,
If anyone has the technical expertise to reply....I'am wondering what is the
advantage (or disadvantage/s) of this item over that of acouple of single
photogenerative cells?
It looks (more or less) like a half bridge circuit to me.
Take care, Meredith
----- Original Message -----
From: John or Jan Lahr
To: psn-l@..............
Sent: 3/5/2004 9:03:08 PM
Subject: Re: new Wood-Anderson in Trieste
I checked on the price of the 1L20. It's $335
from On-Trak Photonics, Inc, Lake Forest, CA.
This is not an inexpensive solution, at least at this time!
John
To: psn-l@..............
From: John or Jan Lahr
Subject: Fwd: new Wood-Anderson in Trieste
The clever, position-sensing system described by Dario Slejko (see below) may be of
some interest to amateurs as well. Note that the URL for Sitek given on his
web site should be:
http://www.sitek.se/
Cheers,
John
Hi all,
If anyone has the technical expertise to reply....I'am wondering what is the
advantage (or disadvantage/s) of this item over that of acouple of single
photogenerative cells?
It looks (more or less) like a half bridge circuit to me.
Take care, Meredith
----- Original Message -----
Sent: 3/5/2004 9:03:08 PM
Subject: Re: new Wood-Anderson in Trieste
I checked on the price of the 1L20. It's $335
from On-Trak Photonics, Inc, Lake Forest, CA.
This is not an inexpensive solution, at least at this time!
John
To: psn-l@..............
From: John or Jan Lahr <johnjan@........>
Subject: Fwd: new Wood-Anderson in Trieste
The clever, position-sensing system described by Dario Slejko (see below) may be of
some interest to amateurs as well. Note that the URL for Sitek given on his
web site should be:
http://www.sitek.se/
Cheers,
John
Subject: Re: new Wood-Anderson in Trieste
From: "Meredith Lamb" meredithlamb@.............
Date: Tue, 9 Mar 2004 22:15:16 -0700
This is a forwarded email reply from Chris Chapman.
----- Original Message -----
From: Meredith Lamb
To: psn-l@..............
Sent: 3/8/2004 11:46:06 AM
Subject: Re: new Wood-Anderson in Trieste
Hi all,
If anyone has the technical expertise to reply.... I'am wondering what is the
advantage (or disadvantage/s) of this item over that of acouple of single
photogenerative cells?
It looks (more or less) like a half bridge circuit to me.
Take care, Meredith
----- Original Message -----
From: John or Jan Lahr
To: psn-l@..............
Sent: 3/5/2004 9:03:08 PM
Subject: Re: new Wood-Anderson in Trieste
I checked on the price of the 1L20. It's $335
from On-Trak Photonics, Inc, Lake Forest, CA.
This is not an inexpensive solution, at least at this time!
John
To: psn-l@..............
From: John or Jan Lahr
Subject: Fwd: new Wood-Anderson in Trieste
The clever, position-sensing system described by Dario Slejko (see below) may be of some interest to amateurs as well. Note that the URL for Sitek given on his
web site should be:
http://www.sitek.se/
Cheers,
John
Hi Meredith,
Looking at the 1L20 data sheet, the resolution is quoted as being about 100 nm. I am uncertain whether this refers to the use of the cell with a laser or not, but I suspect not. The semiconductor lasers may have 10x the noise of a tungsten filament bulb. You can get relatively quiet LEDs, but their construction does not often allow you to use them as point light sources and the change in light output over 0 to 100 deg C range may be a factor of x5. You do have quite a serious thermal stability problem, but it can be solved.
It is relatively easy using large area Si photodiodes and a tungsten filament bulb to get a resolution of 15 nm at 10 Hz bandwidth. You can buy twin / quad photocells on a common substrate.
Regards,
Chris Chapman
This is a forwarded email reply from Chris Chapman.
----- Original Message -----
From: Meredith Lamb
To: psn-l@..............
Sent: 3/8/2004 11:46:06 AM
Subject: Re: new Wood-Anderson in Trieste
Hi all,
If anyone has the technical expertise to reply.... I'am wondering what is the
advantage (or disadvantage/s) of this item over that of acouple of single
photogenerative cells?
It looks (more or less) like a half bridge circuit to me.
Take care, Meredith
----- Original Message -----
From: John or Jan Lahr
To: psn-l@..............
Sent: 3/5/2004 9:03:08 PM
Subject: Re: new Wood-Anderson in Trieste
I checked on the price of the 1L20. It's $335
from On-Trak Photonics, Inc, Lake Forest, CA.
This is not an inexpensive solution, at least at this time!
John
To: psn-l@..............
From: John or Jan Lahr <johnjan@........>
Subject: Fwd: new Wood-Anderson in Trieste
The clever, position-sensing system described by Dario Slejko (see below) may be of some interest to amateurs as well. Note that the URL for Sitek given on his
web site should be:
http://www.sitek.se/
Cheers,
John
Hi Meredith,
Looking at the 1L20 data sheet, the resolution is quoted as being about 100 nm. I am uncertain whether this refers to the use of the cell with a laser or not, but I suspect not. The semiconductor lasers may have 10x the noise of a tungsten filament bulb. You can get relatively quiet L
EDs, but their construction does not often allow you to use them as point light sources and the change in light output over 0 to 100 deg C range may be a factor of x5. You do have quite a serious thermal stability problem, but it can be solved.
It is relatively easy using large area Si photodiodes and a tungsten filament bulb to get a resolution of 15 nm at 10 Hz bandwidth. You can buy twin / quad photocells on a common substrate.
Regards,
Chris Chapman
Subject: ebay auction
From: BOB BARNS royb1@...........
Date: Fri, 12 Mar 2004 10:35:42 -0500
MARK PRODUCTS SEISMOGRAPH SENSORS w/ CABLES Item number: 3803503727
ends 3/18 appears to be 3 geophones
Bob
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: RE: ebay auction
From: "Doug Crice" dcrice@............
Date: Fri, 12 Mar 2004 08:26:53 -0800
These are interesting, but it isn't clear what the natural frequency is.
For earthquake purposes, you would do better to buy one of those =
3-component
4.5 sensors from Larry.
Doug Crice
Geostuff http://www.georadar.com/geostuff.htm
12996 Somerset Drive phone 1-530-274-4445
Grass Valley, CA 95945 USA fax 1-530-274-4446
=20
-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... =
On
Behalf Of BOB BARNS
Sent: Friday, March 12, 2004 7:36 AM
To: psn mail
Subject: ebay auction
MARK PRODUCTS SEISMOGRAPH SENSORS w/ CABLES Item number: 3803503727
ends 3/18 appears to be 3 geophones
Bob
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
__________________________________________________________
Public Seismic Network Mailing List (PSN-L)
Subject: more paper needed...
From: "Kareem Lanier" kareem@.............
Date: Sun, 14 Mar 2004 19:28:13 -0800
Does anyone know where I can get more seismographic paper for my ps2 system.
Kinemetrics has this paper but it's extremely pricey. The dimensions are 24"
x 13.5".
Kareem
----------------------------------------------------------------------------
-------------------
Kareem's HeyJooJoo.Com
- Discover, Explore, Learn & Play
All of my outgoing and incoming emails are scanned for viruses and worms by
my antivirus software.
Does anyone know where I can get more =
seismographic=20
paper for my ps2 system. Kinemetrics has this paper but it's extremely =
pricey.=20
The dimensions are 24" x 13.5".
Kareem
----------------------------------------------------------------=
-------------------------------
Kareem's =
HeyJooJoo.Com - Discover, Explore, =
Learn &=20
Play
All of my =
outgoing and=20
incoming emails are scanned for viruses and worms by my antivirus=20
software.
Subject: Re: more paper needed...
From: Raul Alvarez ralvarez@........
Date: Mon, 15 Mar 2004 06:38:17 -0700
Hi Kareem,
Does the paper have any specific coating? If it's regular paper, you
coud check with an office supply store that carries plotter paper. This
comes in sizes up to about 36". Standard "size" is by letter i.e. size
A, B, C etc. I think "C" paper would fit your need. You will have to
cut it to size.
Raul
Kareem Lanier wrote:
> Does anyone know where I can get more seismographic paper for my ps2
> system. Kinemetrics has this paper but it's extremely pricey. The
> dimensions are 24" x 13.5".
>
> Kareem
>
> -----------------------------------------------------------------------------------------------
> Kareem's HeyJooJoo.Com
> - Discover, Explore, Learn & Play
> All of my outgoing and incoming emails are scanned for viruses and
> worms by my antivirus software.
>
Hi Kareem,
Does the paper have any specific coating? If it's regular paper, you
coud check with an office supply store that carries plotter paper. This
comes in sizes up to about 36". Standard "size" is by letter i.e. size
A, B, C etc. I think "C" paper would fit your need. You will have to
cut it to size.
Raul
Kareem Lanier wrote:
Does anyone know where I can get more
seismographic paper for my ps2 system. Kinemetrics has this paper but
it's extremely pricey. The dimensions are 24" x 13.5".
Kareem
-----------------------------------------------------------------------------------------------
All of my
outgoing and incoming emails are scanned for viruses and worms by my
antivirus software.
Subject: RE: more paper needed...
From: "Kareem Lanier" kareem@.............
Date: Mon, 15 Mar 2004 06:17:08 -0800
There's no special coating that I'm aware of. I've been using regular paper
that was simply cut. This was messy and time consuming to have this done.
Although when I was able to get a hold of the actual seismograph paper, it
was glossy.
Kareem
_____
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of Raul Alvarez
Sent: Monday, March 15, 2004 5:38 AM
To: psn-l@..............
Subject: Re: more paper needed...
Hi Kareem,
Does the paper have any specific coating? If it's regular paper, you coud
check with an office supply store that carries plotter paper. This comes in
sizes up to about 36". Standard "size" is by letter i.e. size A, B, C etc.
I think "C" paper would fit your need. You will have to cut it to size.
Raul
Kareem Lanier wrote:
Does anyone know where I can get more seismographic paper for my ps2 system.
Kinemetrics has this paper but it's extremely pricey. The dimensions are 24"
x 13.5".
Kareem
----------------------------------------------------------------------------
-------------------
Kareem's HeyJooJoo.Com
- Discover, Explore, Learn & Play
All of my outgoing and incoming emails are scanned for viruses and worms by
my antivirus software.
There's no special =
coating that=