Hi Larry (Conklin) -
I'm just now catching up on the PSN email traffic and the "Haunted System" =
thread.=A0=A0
=A0
FWIW, my SG seems to do the same thing as=A0yours from time to time.=A0 I b=
uilt the sensor many=A0years ago, and built up the electronics board from L=
arry Cochrane's schematics.=A0=A0I am still running it at present, alongsid=
e my=A0much newer=A0force-balance vertical instrument.=A0=20
=A0
Every so often, the SG channel will=A0either (1) go totally dead=A0silent, =
or (2) get extremely noisy.=A0 In the past when I see this, I'll power down=
 the instrument and run through the various connectors in the system,=A0re-=
level the sensor, and fire it back up.=A0 And everything=A0is OK in that ch=
annel for the next several weeks / months.=A0 I have yet to=A0successfully =
trace the problem to an offending=A0connector or electronic part.=A0=20
=A0
So my SG seems "haunted" by the same=A0ghost as yours.=A0 ...go figure...
=A0
Steve Jones
AlabamaQuake=A0=A0=A0

--- On Thu, 6/21/12, Larry Cochrane  wrote:


From: Larry Cochrane 
Subject: Re: Haunted system misbehaving again
To: psnlist@..............
Date: Thursday, June 21, 2012, 5:00 PM


Hi Larry,

Have you tried locking down the pendulum so it can't move and letting you s=
ystem run=20
for a while? Looking at the schematic I see two parts I would replace. They=
 are the=20
two back-to-back 100uf (I think) capacitors driving the feedback coil. I wo=
uld=20
replace them with one 47uf non-polarized cap. DigiKey has these=20
http://www.digikey.com/product-detail/en/ECE-A1VN470U/P1190-ND/227631 in-st=
ock.

Regards,
Larry Cochrane
Webtronics

On 6/20/2012 7:11 PM, Larry Conklin wrote:
> Hi Roger,
>
> I think I remember your having posted an account of your "rug affair".
> In fact I think that it prompted me to improve the leveling screws on my
> system, which at the time were rather flimsy. I replaced them with
> larger, stiffer screws and I think that it may have helped, or even
> "solved" the problem for a while.=A0 I'm now using fairly substantial
> screws and the system is (and already had been) sitting on a couple of
> 1/8 inch thick strips of aluminum that are epoxied to the basement
> floor.=A0 The assumption being that the plates are a more rigid surface
> than the bare concrete would be.
>
> The only pivot points I can identify are the pendulum hinge itself
> (consisting of thin metal shim material, phosphor bronze or some such).
> But there is certainly the possibility that the contacts between the
> feet and the plates might shuck around a little with temperature changes?
>
> I also have had a series of cover experiments.=A0 Original cover was a
> wood box that sat on the frame of the sensor.=A0 Very bad idea. Rebuilt i=
t
> to fit over the sensor and sit on the floor.=A0 Better, but probably
> vulnerable to transmitting noise to the instrument.=A0 Added "stuffing" t=
o
> fill up the unused volume and suppress air movement. Not much noticeable
> change.=A0 Current cover is light weight, built of insulating board and
> sitting on the floor.=A0 At times I've duct taped it to the floor, but at
> the moment it's just sitting there.=A0 Maybe putting the tape back would
> be a good idea.
>
> But the overall behavior of the problem makes a lot of these
> possibilities seem unlikely.=A0 In one subset of episodes of the problem,
> the noise starts abruptly and then continues indefinitely for days of
> weeks at a time.=A0 The data shown on my web page is typical of this
> "class".=A0 (And I noticed that this episode started on March 30, and is
> still ongoing, although there were couple of periods of a week or so
> duration since them where things were much better.)=A0 Other episodes hav=
e
> emerged gradually over the course of several hours, continued for days
> or even weeks at a time and then subsided.=A0 I'm at a loss to come up
> with a theory that is consistent with both kinds of behavior.=A0 And none
> of the experiments I've tried have made any clear and lasting impact on
> the problem, although I've tried a few things that I've thought fixed
> it, only to have it crop up six months later.
>
> I guess that's what makes this business interesting.
>
> Larry
>
>
>
> On 6/20/2012 9:41 AM, RSparks wrote:
>> Hi Larry,
>>
>> My experience parallels yours with loose mounted components.=A0 I once
>> went through a rug to concrete below and failed to make good contact
>> with one screw on the concrete.=A0 I was effectively floating on the rug
>> with one of the three seismometer legs!=A0=A0=A0Very noisy!
>>
>> Based on this experience, I am careful to make all mechanical contacts
>> solid connections in some way.=A0 I even drilled holes into the concrete
>> and mounted my seismometer solidly.=A0 I thought there was a small
>> improvement in the noise level after taking this somewhat extreme
>> measure.
>>
>> I also avoid pivot points in favor of bending joints to avoid noise.
>> Friction is present in our seismometers if there is a moving joint and
>> mechanical friction is always noise.
>>
>> Maybe look more carefully at any mechanical connection that might be
>> loose, maybe=A0 not only in the leveling screws.=A0 Look also at the
>> mounting of the surrounding air/insulating box, making sure it is not
>> rocking from the ever present 0.2 Hz peak noise or more likely, the
>> thermal air currents in your room.
>>
>> Good luck,
>>
>> Roger
>> .------ ------ ------ ------ ------ ------ ------ ------ ------
>> ------. | Message 3 | '------ ------ ------ ------ ------ ------
>> ------ ------ ------ ------' Subject: Haunted system misbehaving again
>> From: Larry Conklin  Date: Tue, 19 Jun 2012
>> 14:54:30 -0400 I have an SG sensor that has intermittently had serious
>> noise problems, literally for years. Mechanically, it is very similar
>> to the design that is shown on Larry's PSN web site, and it uses
>> Larry's electronics board, which I believe he is no longer selling.
>> When the thing is running properly I've been quite happy with it. But
>> occasionally, for reasons I have never been able to pin down, it
>> exhibits extreme low frequency noise, to the point where it is
>> basically useless. The current episode began with the system running
>> very well, but it was in need of leveling, which I've typically need
>> to do every couple of weeks or so. Before I adjusted the leveling
>> screw, it was quiet. After messing with it it became extremely noisy.
>> So, you'd believe that it was some sort of mechanical problem, right?
>> And I've had several other episodes that began the same way. This
>> time, when I brought it upstairs on the bench, I did in fact discover
>> that the lock nut on the leveling screw was loose, and I "fixed" the
>> problem by re-tightening it. Ran pretty well for a week or so
>> thereafter, but not really as quiet as it should be. Then, it
>> spontaneously got quite noisy again, interspersed with periods where
>> it ran ok. I have a lot of other history with seemingly mutually
>> exclusive symptoms/probable causes, but the bottom line is I don't
>> have a clue what is really going on. I'm tempted to believe that there
>> is something subtle wrong with the electronics board, but in past
>> attempts to trouble shoot it, haven't been able to find anything. If
>> there is anyone out there who has one of Larry's SG boards that
>> they're willing to part with, I'd be interested in buying it. If for
>> no other reason than to rule out the board as the source of the
>> problem. For the curious, I have a little web page that I dump drum
>> reports up to daily. The report for today (so far) shows a
>> particularly noisy day, but does include the quake that happened in
>> the Aleutians this afternoon. The page also shows drum reports from
>> the day this round of the problem started. The day started just fine,
>> until the big transient that resulted when I went down and adjusted
>> the leveling, at which point all hell broke loose. You can also see
>> the consequences of two subsequent leveling adjustments later in the
>> day. After that data was recorded, I didn't mess with the thing for
>> maybe a week, until I finally got around to taking a closer look at
>> it, at which point I realized that the leveling screw was loose and
>> re-tightened it. I'd be very interested in anyone's thoughts on this
>> problem. The link to my web page follows:
>> http://home.roadrunner.com/~lwconklin/ Larry Conklin Liverpool, NY .-
>> __________________________________________________________
>>
>> Public Seismic Network Mailing List (PSNLIST)
>>
>> To leave this list email PSNLIST-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 (PSNLIST)
>
> To leave this list email PSNLIST-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 (PSNLIST)

To leave this list email PSNLIST-REQUEST@.............. with=20
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.
Hi Larry (Conklin) -
I'm just now catching up on the PSN email traffic and the "Haunted Sys=
tem" thread.  
 
FWIW, my SG seems to do the same thing as yours from time to time=
..  I built the sensor many years ago, and built up the electronic=
s board from Larry Cochrane's schematics.  I am still running it =
at present, alongside my much newer force-balance vertical instru=
ment.  
 
Every so often, the SG channel will either (1) go totally dead&nb=
sp;silent, or (2) get extremely noisy.  In the past when I see this, I=
'll power down the instrument and run through the various connectors in the=
 system, re-level the sensor, and fire it back up.  And everythin=
g is OK in that channel for the next several weeks / months.  I h=
ave yet to successfully trace the problem to an offending connect=
or or electronic part.  
 
So my SG seems "haunted" by the same ghost as yours.  ...go =
figure...
 
Steve Jones
AlabamaQuake   

--- On Thu, 6/21/12, Larry Co=
chrane <lcochrane@..............> wrote:


From: Larry Cochrane <lcochrane@...............
>
Subject: Re: Haunted system misbehaving again
To: psnlist@webtro=
nics.com
Date: Thursday, June 21, 2012, 5:00 PM


Hi Larry,

Have you tried locking down the pen=
dulum so it can't move and letting you system run 
for a while? Looking =
at the schematic I see two parts I would replace. They are the 
two back=
-to-back 100uf (I think) capacitors driving the feedback coil. I would 
=
replace them with one 47uf non-polarized cap. DigiKey has these 
http://www.digikey.com/product-detail/en/ECE-A1VN470U/P1190=
-ND/227631 in-stock.

Regards,
Larry Cochrane
Webtronics
On 6/20/2012 7:11 PM, Larry Conklin wrote:
> Hi Roger,
>> I think I remember your having posted an account of your "rug affair=
".
> In fact I think that it prompted me to improve the leveling scre=
ws on my
> system, which at the time were rather flimsy. I replaced t=
hem with
> larger, stiffer screws and I think that it may have
 helped, or even
> "solved" the problem for a while.  I'm now us=
ing fairly substantial
> screws and the system is (and already had be=
en) sitting on a couple of
> 1/8 inch thick strips of aluminum that a=
re epoxied to the basement
> floor.  The assumption being that t=
he plates are a more rigid surface
> than the bare concrete would be.=

>
> The only pivot points I can identify are the pendulum hing=
e itself
> (consisting of thin metal shim material, phosphor bronze o=
r some such).
> But there is certainly the possibility that the conta=
cts between the
> feet and the plates might shuck around a little wit=
h temperature changes?
>
> I also have had a series of cover ex=
periments.  Original cover was a
> wood box that sat on the fram=
e of the sensor.  Very bad idea. Rebuilt it
> to fit over the se=
nsor and sit on the floor.  Better, but probably
>
 vulnerable to transmitting noise to the instrument.  Added "stuffing"=
 to
> fill up the unused volume and suppress air movement. Not much n=
oticeable
> change.  Current cover is light weight, built of ins=
ulating board and
> sitting on the floor.  At times I've duct ta=
ped it to the floor, but at
> the moment it's just sitting there.&nbs=
p; Maybe putting the tape back would
> be a good idea.
>
>=
; But the overall behavior of the problem makes a lot of these
> poss=
ibilities seem unlikely.  In one subset of episodes of the problem,> the noise starts abruptly and then continues indefinitely for days of=

> weeks at a time.  The data shown on my web page is typical of=
 this
> "class".  (And I noticed that this episode started on Ma=
rch 30, and is
> still ongoing, although there were couple of periods=
 of a week or so
> duration since them where things were much
 better.)  Other episodes have
> emerged gradually over the cour=
se of several hours, continued for days
> or even weeks at a time and=
 then subsided.  I'm at a loss to come up
> with a theory that i=
s consistent with both kinds of behavior.  And none
> of the exp=
eriments I've tried have made any clear and lasting impact on
> the p=
roblem, although I've tried a few things that I've thought fixed
> it=
, only to have it crop up six months later.
>
> I guess that's =
what makes this business interesting.
>
> Larry
>
>=

>
> On 6/20/2012 9:41 AM, RSparks wrote:
>> Hi Larry,=

>>
>> My experience parallels yours with loose mounted c=
omponents.  I once
>> went through a rug to concrete below an=
d failed to make good contact
>> with one screw on the concrete.&n=
bsp; I was effectively floating on the rug
>> with one of
 the three seismometer legs!   Very noisy!
>>
&g=
t;> Based on this experience, I am careful to make all mechanical contac=
ts
>> solid connections in some way.  I even drilled holes in=
to the concrete
>> and mounted my seismometer solidly.  I tho=
ught there was a small
>> improvement in the noise level after tak=
ing this somewhat extreme
>> measure.
>>
>> I al=
so avoid pivot points in favor of bending joints to avoid noise.
>>=
; Friction is present in our seismometers if there is a moving joint and>> mechanical friction is always noise.
>>
>> Mayb=
e look more carefully at any mechanical connection that might be
>>=
; loose, maybe  not only in the leveling screws.  Look also at th=
e
>> mounting of the surrounding air/insulating box, making sure i=
t is not
>> rocking from the ever present 0.2 Hz peak noise
 or more likely, the
>> thermal air currents in your room.
>=
>
>> Good luck,
>>
>> Roger
>> .----=
-- ------ ------ ------ ------ ------ ------ ------ ------
>> ----=
--. | Message 3 | '------ ------ ------ ------ ------ ------
>> --=
---- ------ ------ ------' Subject: Haunted system misbehaving again
>=
;> From: Larry Conklin <lconklin@............> Date: Tue, 19 Jun 2012
>> 14:54:3=
0 -0400 I have an SG sensor that has intermittently had serious
>>=
 noise problems, literally for years. Mechanically, it is very similar
&=
gt;> to the design that is shown on Larry's PSN web site, and it uses>> Larry's electronics board, which I believe he is no longer sellin=
g.
>> When the thing is running properly I've been quite happy
 with it. But
>> occasionally, for reasons I have never been able =
to pin down, it
>> exhibits extreme low frequency noise, to the po=
int where it is
>> basically useless. The current episode began wi=
th the system running
>> very well, but it was in need of leveling=
, which I've typically need
>> to do every couple of weeks or so. =
Before I adjusted the leveling
>> screw, it was quiet. After messi=
ng with it it became extremely noisy.
>> So, you'd believe that it=
 was some sort of mechanical problem, right?
>> And I've had sever=
al other episodes that began the same way. This
>> time, when I br=
ought it upstairs on the bench, I did in fact discover
>> that the=
 lock nut on the leveling screw was loose, and I "fixed" the
>> pr=
oblem by re-tightening it. Ran pretty well for a week or so
>> the=
reafter, but not really as quiet as it should be. Then,
 it
>> spontaneously got quite noisy again, interspersed with peri=
ods where
>> it ran ok. I have a lot of other history with seeming=
ly mutually
>> exclusive symptoms/probable causes, but the bottom =
line is I don't
>> have a clue what is really going on. I'm tempte=
d to believe that there
>> is something subtle wrong with the elec=
tronics board, but in past
>> attempts to trouble shoot it, haven'=
t been able to find anything. If
>> there is anyone out there who =
has one of Larry's SG boards that
>> they're willing to part with,=
 I'd be interested in buying it. If for
>> no other reason than to=
 rule out the board as the source of the
>> problem. For the curio=
us, I have a little web page that I dump drum
>> reports up to dai=
ly. The report for today (so far) shows a
>> particularly noisy da=
y, but does include the quake that happened in
>> the
 Aleutians this afternoon. The page also shows drum reports from
>>=
; the day this round of the problem started. The day started just fine,
=
>> until the big transient that resulted when I went down and adjuste=
d
>> the leveling, at which point all hell broke loose. You can al=
so see
>> the consequences of two subsequent leveling adjustments =
later in the
>> day. After that data was recorded, I didn't mess w=
ith the thing for
>> maybe a week, until I finally got around to t=
aking a closer look at
>> it, at which point I realized that the l=
eveling screw was loose and
>> re-tightened it. I'd be very intere=
sted in anyone's thoughts on this
>> problem. The link to my web p=
age follows:
>> http://home.roadrunner.com/~lwconklin/ Larry Conklin L=
iverpool, NY .-
>>
 __________________________________________________________
>>
=
>> Public Seismic Network Mailing List (PSNLIST)
>>
>&=
gt; To leave this list email PSNLIST-REQUEST@.............. with the body
>=
;> of the message (first line only): unsubscribe
>> See http://www.sei=
smicnet.com/maillist.html for more information.
>>
>
=
>
> __________________________________________________________
=
>
> Public Seismic Network Mailing List (PSNLIST)
>
> =
To leave this list email PSNLIST-REQUEST@.............. with
> the body of=
 the
 message (first line only): unsubscribe
> See http://www.seismicnet.com/mail=
list.html for more information.
>

________________________=
__________________________________

Public Seismic Network Mailing Li=
st (PSNLIST)

To leave this list email PSNLIST-REQUEST@.............. with=
 
the body of the message (first line only): unsubscribe
See http://www.sei=
smicnet.com/maillist.html for more information.
<=

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