Subject: Re: Noise Reduction From: John Hernlund hernlund@....... Date: Fri, 30 Jun 2000 15:39:49 -0700 (MST) On Fri, 30 Jun 2000, Doug Crice wrote: > I'll let one of our mathmaticians answer that one. When you get to a > certain point in life, you remember the results but not the derivation, > especially in statistics. I believe that the basic problem is that each > sensor picks up some random noise along with the signal. So when you > add up the signal from N sensors you also add up N sets of random > noise. When random noise signals are added they get bigger by square > root of N. The signal gets bigger by N so signal-to-noise improves > N/(square root of N). > I don't know the answer in Winquake. > Doug Doug is basically right. The whole concept revolves around the central theorem of statistics: "the mean value theorem." The square root of N term comes in to describe the "spread" or "deviation" in the data using some kind of distribution model. Different distributions are used for different types of random processes. All the theorem says is that the variance goes sufficiently close to zero as the number of samples becomes close to infinity. Most random processes have a decreasing spread that goes roughly as: spread = constant/sqrt(N) The constant will depend on other parameters. Note that this converges very slowly. This is the limiting factor in a type of computation called "Monte Carlo Methods" which use probability and random processes to model or compute very complicated situations. They converge too slow for most people's taste however. But we use this method to calculate the 3-D FFT integral for transmission electron microscopy to get a good estimate of the brightness for diffraction spots. Anyways... John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise Reduction From: ChrisAtUpw@....... Date: Fri, 30 Jun 2000 21:08:15 EDT Dick Webb, The Infrasound CTBT Stations use three sensors in a more or less equilateral triangle with a fourth in the centre. They look for cross correlation between the four signals assuming that the sound source comes from one direction, scanning 360 Deg and at a range of propagation velocities, by storing and then addressing signals taken at different times. Whether you would want to a) fund the hardware which includes a serious amount of computer power and b) could get hold of / write suitable software, is your decision, but the system does apparently work. The root N reduction in noise only applies to random noise. If the 'noise' isn't random, or is common to two or more sensors although with different phases, it may or may not add, just like signal. I have a 12 bit A/D converter, but it is noisy, so I can only rely on it to 10 bit accuracy. If the input signal stays the same, averaging 4 separate conversions will give me ~11 bit accuracy. To get ~12 bit accuracy I have to average 16 conversions (minimum). To be absolutely certain of 12 bit accuracy, I have to average 64 conversions..... I wrote a short programme storing and averaging the data stream to convince myself that this would work and it does. If your 16 bit A/D converter is noisy, keep it working hard! Have you tried altering the bandpass of your electronic filters, or maybe having two sets of filters and comparing the outputs? How about recording a higher frequency 'environmental noise' channel so that you can try to identify false signals? Could this give you the best improvement / cost + effort? Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Noise Reduction From: Dick Webb dwebb2@.............. Date: Sat, 01 Jul 2000 08:19:49 -0400 Thanks, My old and hated statistics class is coming back to me. I agree that I could filter or band pass most of the noise. My interest in combining the seismometer outputs arose mainly because I have the 3 seismometers and I wanted to get the most from them (I'm the guy who hoped that you could convert a vertical to horizontal). If it is possible to combine the outputs after signal processing, why would it not be possible to do it with the raw signals, i.e. directly out of the units. Wouldn't you be looking as a sum of the voltages? Dick __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Noise Reduction From: ChrisAtUpw@....... Date: Sat, 1 Jul 2000 13:48:40 EDT Dick Webb, > I agree that I > could filter or band pass most of the noise. My interest in combining the > seismometer outputs arose mainly because I have the 3 seismometers and I > wanted to get the most from them. If it is possible to combine the > outputs after signal processing, why would it not be possible to do it with > the raw signals.... ? Sure you can average the voltages OK. No problem if all the instruments have roughly the same response and are only a few hundred feet apart. You need to check that no one is much noisier than any other, or it's noise will dominate the output and also that they all respond to a distant quake with the same polarity signal. If the noise is random you might get a reduction of 1/root3 i.e. ~ 42% reduction. I suggested filtering / recording environmental noise as this can give a much greater reduction and may allow you to identify peaks in the 'earthquake' recording caused by environmental noise which might otherwise be more difficult to interpret. The quick way to find out is to hitch up another OP-AMP..... but don't expect to see a large difference. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: vbb transient noise From: S-T Morrissey sean@........... Date: Sat, 1 Jul 2000 15:47:00 -0500 (CDT) Barry, Sorry I have not responded sooner, but an emergency came up when a contractor tore up the fiber-optic cable linking the processors at the IRIS station CCM. I've ended up replacing about 100 meters of cable, making new "pipe vaults" for the connections that have to survive flooding 10 to 12 meters deep. Hopefully the additional splice in the 2.4km cable will not push our optical power budget. Regarding LP transient noise from your VBB vertical. This is not an uncommon problem with broadband seismometers operating at extended periods, like in excess of 20 seconds. THe longer the operating period, the more sensitive the sensor is to steps in displacement, which show up in the velocity output as one-sided lumps with about the duration of the integrator period. I can only guess at some possible causes, so I will pass on my experience for everyone's benefit. The manufacturers of commercial broadband sensors actually suggest being tolerant of these transients during the "settling in" period of the instrument, which may last several weeks as all the parts come into thermal equalibrium and mechanical stresses dissipate. Of course, the same is true for the enclosure, pier, vault, etc., even the lay of the cable to the seis is of concern. Once an installed instrument has established itself as reliably quiet, the sudden incidence of transient noise can be attributed to either the electronics of the feedback, the mechanics of the sensor, the immediate environment (covers, cable, vault), or the regional environment. You mention seeing similar transients on a station in Norway. This would be pure coincidence. As you know, the only transient-like or one-sided impulsive phases would be direct compressive arrivals of teleseismic quakes: most of the energy from distant quakes that a broadband would record are long sequences of super-imposed sine waves that would follow the direct waves on most of the broadband sensors worldwide. Assuming that the electronics worked OK when it was installed, the main source of transients is dampness in the enclosure, which particularly affects the high impedances of the integrator. Intermittent conduction of contamination, like fingerprints, can be a problem. The STS-1 integrator components are actually mounted on ceramic standoffs to deal with this. Although seismometers are generally installed in dark, damp, moldy places, even in dripping caverns, no amount of dampness within the system can be tolerated; the enclosure should be sealed, using vapor tight connectors (or seal them with silica gel around the inside terminals). The enclosure(s) should be desiccated with several units of diatomacious earth (cheaper than silica gel) and an indicator strip should be installed to indicate that the desiccant is active. (I shocked some people by drilling 1.5" viewports in the covers of the Streckheisn electronics enclosure so I could install the indicator inside them). The desiccant can absorb about 1cc of water per unit; with 5 units in the 8"x10"x3" box, it stays active for about 5 years in the dampness of a cavern. In my opinion, there is little point using desiccant without the humidity indicator strips. (from Humidial Corp.) The connectors should also be (or be made) weather tight. Some have O ring seals, which are good only until the connector is dropped on the dirt floor. If I have any doubt, I use stretched self-vulcanizing tape over-wrapped with vinyl electrical tape that can be cut away if/when the connection has to be removed. The seismometer enclosure itself should also be sealed and desiccated if it is in a damp environment. The desiccant needs to be secured so that as it expands it doesn't touch any moving part. If the seis enclosure is tight enough to stay dry, it will also be spider and waterbug proof. Bugs can make interesting transients. I use wide, thin foam weatherstrip to seal the cover; it does breathe slightly along its length, which is preferable to absolute seals that might equalize barometric pressure through a pinhole with a little jet that blows the mass around. Another problem has occurred with commercial seismometers that use large capacitive transducers with close (0.2mm) clearances. ANY contamination, like an eyelash, will cause contact. A recurring problem has been peeling adhesives or coatings. These are often detected by strong local vibration, like a good stomp, that causes a transient. For the speaker coil/magnet transducer, small magnetic slivers on the poles can cause this. I use an inside-out strip of masking tape to repeatedly clean the magnet gap as well as to ensure that there are no dog hairs on the coil. For the home-made seis, another problem can arise from the flexures, especially if they are epoxied in place. They may be coming unglued from improper cleaning at assembly, or some residual excess glue might be in the flexing area. I haven't had this problem with the later versions of the large vertical. Of course, any spontaneous mechanical change of the moving system results in a transient; often these are bidirectional micropositioning due to temperature changes. You mention that you suspect changes in the slab under the seis, possibly due to temperature or drying out. This is always possible, but unless the cause is really obvious, like desiccation cracks, I would expect slow changes rather than transients. If there are large enough dimensional changes, the feet of the seis base may be moving on the slab; we always use glass plates under the feet to allow for smooth differential expansion; these are often epoxied to the pier or slab surface. Highly glazed ceramic tiles will also do; I used them for the top surface of the pier here. Other sources of strange transients from the environment can come from slight movements of the covers, cables, etc. The cable should always approach the seis laying on the pier, making S-turns or possibly a circle around the seis. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: vbb transient noise From: barry lotz gbl@....... Date: Sat, 01 Jul 2000 13:21:18 -0700 Sean Thomas Thanks for the valuable assistance wrt transient sources. Sometimes I get so concerned about getting the sensor to work properly that the subtile considerations are overlooked. Also I find that when the sensor is working properly I don't want to disturb it for fear of having to go thru all the effort in getting it running correctly again. I guess if one is going to operate a homegrown sensor(s) one has to resolve to disturb it's operation to experiment with improvements. As probably happened with many others, that's when a large event occurs. Thanks again Barry __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Mars photos From: meredith lamb mlamb1@.......... Date: Sun, 02 Jul 2000 11:30:33 -0700 Hi all, OK.....it turns out that nothing photo wise hasn't been relatively brought up and speculated on or explained on the Mars pictures. Perhaps the best web site for viewing a large variety of features (12 page list of highlights, subjects, and better pictures) is at: http://www.msss.com/mars_images/moc/MENUS/moc_by_date.html Still.....its fun to pot shoot their maps....one never knows....ha. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New PSN event file format. From: Larry Cochrane cochrane@.............. Date: Sun, 02 Jul 2000 15:18:28 -0700 All, I made a few changes to the format (see http://www.seismicnet.com/psn4tbl.html) based on the comments from Edward. All floats have been changed to doubles and I changed some bytes and shorts to longs. The variable length section can now have data fields larger then 255 bytes. At 06:01 PM 6/29/00 -0600, Edward wrote: >With respect to the "DateTime Structure", I would suggest that since you are >using a "long" to store the fraction of seconds, you might as well store >nanoseconds. I mean, if you got, i.e., the precision, why not flaunt it? I renamed the field to nanoseconds. >you >never know when you'll need it. Also, it would be useful to include a clock >correction in seconds as a double (type/length) that could be added to the >nominal time that the samples were originally time-stamped with when recorded. >Particularly in the case of "unlocked" data, that estimate of true time might be >fuzzy and controversial. It seems to me that the start time should already include this information. Basically the start time of the first sample is based on the best information the data logger has at the time it saves the data to disk. > >> The next sections is the seismogram data. The data array can be either 16 >> bit integer, 32 bit integer or floating point. After the data is two CRC-16 >> bytes. This is used to verify the integrity of the headers and data sections. > >Do you mean dis dat or dat one? When referring to the discrete values of the >recorded seismic timeseries, I always try to use the word "samples" rather than >"data" to distinguish them from the other data, such as time-stamps, instrument >constants, or station info. I changed some of the places where I used the word data to samples. >Two thoughts: > >1) To avoid worrying about the different "Type/Length" of parameters, all >parameters -- other than the "Variable Length" info -- could be stored in the >form of the most inclusive type: 8-byte double floats. Though this will waste >some space -- which will be small compared to the data-mass of the samples -- its >uniformity will be easier to program and it will accomodate future upgrades of >parameter precision. Done. > >2) As I said in a presentation at the IRIS workshop in 1983 that was held to >launch the PASSCAL Program: "seismic data is like nuclear waste: both need to be >stored in dumps while awaiting processing", and we need a "Cosmic Database" to >store all these data and make them rapidly accessible to all. Got any ideas about >putting it all together, such that all the header info of all event/volume files >can be rapidly queried and the corresponding waveform samples can be retrieved >via the Web? One step at a time.....Any database programmers out there????? -Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New PSN event file format. From: The Lahrs johnjan@........ Date: Sun, 02 Jul 2000 18:52:15 -0600 At 04:18 PM 7/2/00 , you wrote: >All, > >I made a few changes to the format (see >http://www.seismicnet.com/psn4tbl.html) based on the comments from Edward. >All floats have been changed to doubles and I changed some bytes and shorts >to longs. The variable length section can now have data fields larger then >255 bytes. > > Also, it would be useful to include a clock > >correction in seconds as a double (type/length) that could be added to the > >nominal time that the samples were originally time-stamped with when >recorded. > >Particularly in the case of "unlocked" data, that estimate of true time >might be > >fuzzy and controversial. > >It seems to me that the start time should already include this information. >Basically the start time of the first sample is based on the best >information the data logger has at the time it saves the data to disk. Hi Larry, I think the problem is that if the time originally recorded for the first sample is not correct, then it's better to use a correction field than to simply change the number that was originally stored with the file. In that way, one always knows what the original time stamp was and the correction tells how far the clock was off. If you later figure out a better clock correction, then a new correction can be used and you never loose track of what you're doing, or have done. John John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 john@........ http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Near S. Coast of Honshu, Japan From: meredith lamb mlamb1@.......... Date: Mon, 03 Jul 2000 11:36:16 -0700 Any thoughts on all the continuing quakes in this region from anyone? They seem to be running across a plate tip area, almost like it could be re-defining the plate boundary edge, and/or "breaking" the tip away from the rest of the plate mass? At the continuing rate of quakes over time....something must be going on there....but who knows, they could cease soon too. Anyone know of a web URL, with any english translations to this activity? Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Near S. Coast of Honshu, Japan From: John Hernlund hernlund@....... Date: Mon, 03 Jul 2000 13:15:22 -0700 (MST) On Mon, 3 Jul 2000, meredith lamb wrote: > Any thoughts on all the continuing quakes in this region from > anyone? > They seem to be running across a plate tip area, almost like > it could be re-defining the plate boundary edge, and/or "breaking" > the tip away from the rest of the plate mass? > At the continuing rate of quakes over time....something must > be going on there....but who knows, they could cease soon too. > Anyone know of a web URL, with any english translations to > this activity? > Thanks, Meredith Lamb Meredith, Japan is probably the best studied seismic region in the world. They have literally carpeted the islands with seismometers. The quakes at shallow parts of the subduction zone show a group of linear trends parallel to the plate motion. Some have interpreted this to be the subduction of sea mounts which scrape along the bottom of Japan as they go down. I saw the plots once before and it looked fairly convincing because the arrangement of these seismicity lineations seems to be distributed geometrically much like the sea mounts to the east. I have also seen some of the most fantastic tomographic plots from Japan. If I come across any good web links I'll let you know where to find them. Most of the east coast of Asia exhibits a phenomenon known as "back-arc spreading." One explanation for this is that as the lithosphere sinks into the upper mantle it pulls some of the mantle above it down, which creates a sort of eddy current above the slab. The eddy then pulls the lithosphere above it along the surface towards the trench, thus causing spreading behind the subduction zone. Japan has a smaller back-arc region behind it than the areas to the south. But it does seem like it will be pulled further from Asia over time along with Kamchatka to the north. The rate of subduction under Japan is fairly high, and will probably persist for a long while to come. The lithosphere sinking to the north is older and cooler than that to the south, which might have helped to create the type of corner you are thinking about. It is interesting to think about back-arc spreading in terms of the western US when the Farallon plate used to go down on the west coast along the entire front. There are a lot of lower basins to the east (i.e. Basin and Range), which might have something to do with this type of activity. The corner of slab extending beneath Japan and under North Korea/far east China might be one of these areas where slabs sink into the upper mantle but begin to pile up at the 660 km discontinuity, awaiting the time when enough weight will be added for a "flushing" event to occur where it falls into the lower mantle. This is very fun stuff to think about... John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Near S. Coast of Honshu, Japan From: Canie canie@........... Date: Mon, 03 Jul 2000 22:23:23 -0700 At 11:36 AM 7/3/00 -0700, you wrote: >Any thoughts on all the continuing quakes in this region from >anyone? This has captured my interest as well - it seemed no surprise that there was a 6.1 with all this activity - I also read an article this morning that said they were evacuating (or lots of folks were leaving) the island where most of these are occurring - I would expect something unusual is happening - Other comments in the news were that some thought the volcanic activity has caused some plates to come 'unglued' so to speak. Here's a good link to earthquake news: http://search.news.yahoo.com/search/news?p=earthquake&n=30 Canie __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Near S. Coast of Honshu, Japan From: John Hernlund hernlund@....... Date: Tue, 04 Jul 2000 11:33:14 -0700 (MST) On Mon, 3 Jul 2000, Canie wrote: > At 11:36 AM 7/3/00 -0700, you wrote: > >Any thoughts on all the continuing quakes in this region from > >anyone? > I would expect something unusual is happening - Other comments in the news > were that some thought the volcanic activity has caused some plates to come > 'unglued' so to speak. > Canie A major idea about subduction zone earthquakes is that the H2O contained in the mineral structures is exsolved after the rocks at the top of the slab reach a certain temperature. This then leaves the rocks and lubricates faults and fractures in the slab, which because it is under stress slips due to the reduction of friction. If there is some kind of big "de-watering" event occurring in the slabs then this could trigger an episode such as this one in Japan. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ELF precursor to Honshu Japan From: Arie Verveer ajbv@............ Date: Wed, 05 Jul 2000 10:08:32 +0800 Hi, This may be of interest. For the last three weeks one of my stations channels is an ELF detector (au4). It was set up to confirm or deny some magnetic effects that I observed from a fluxgate magnetometer. But in the process the device has captured some tantalizing traces that may be associated with large quakes. Basically what Charlie Plyler has suggested. See www.elfrad.com Anyhow a good example of such a trace has been sent to the event files. 000704a.au4 on the 7/4/00. It shows increased activity some 4.6 hours before the mb5.4 Honshu quake. Similarly but with less intensity an increase of activity occurred some 2.6 hours for the Honshu Mb6.1 event on the 7/1/00. Maybe the less intensity quake has a better signal due to some heating effects from the previous quakes. Maybe? Also from the Chile earthquake (Mw6.4 6/16/00 7:55:35 UTC) there has been some amazing ELF radiation matches. There appears to be ELF detection as various phases bounce through the same active area 120 km below the surface. As there are no "P" and "S" arrival times the station recorded the event as it happened. So far I've been waiting for another big quake in Chile to confirm these readings. One thing, I get the impression that the deeper quakes show better traces. I would be interested in any views. I for one, believed that ELF radiation would be local to an event, if detected at all. Maybe i'm wrong, I have been known to be. Arie Ps: The file 000704a.au4 is 8 hours long. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: noisy power supply From: Angel Rodriguez angel@............ Date: Tue, 4 Jul 2000 23:44:12 -0500 Hi, I just got me new computer and much to my chagrin now all four of the traces on SDR are much noisier. Little spikes, jus ta few counts. When I turn off the new computer the noise goes away and when turn it on the noise comes back. Obviously one solution is to not turn on the computer. Are there any others? Best regards, Angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: Larry Cochrane cochrane@.............. Date: Tue, 04 Jul 2000 23:04:38 -0700 Angel and others having this problem, I have noticed this problem with some motherboards. This happens on newer motherboards that have switching power supplies that place a lot of high frequency noise onto the + and/or - 12 volt supply lines. This noise gets into the multiplexor chip and op-amp on the A/D card. About two months ago I started adding two inductors to my A/D card that filters out the problem. The modifications are easy too make, but require some soldering skills. I will create a web page that documents the changes needed to add the inductors if anyone wants to modify their board. Just about any small inductor will work as long as the DC resistance is only a few ohms. If you don't have a supply of inductors at hand I can send you two if you send me an envelope with return postage. If your not into soldering you can send me your A/D board and I will make the modifications for free. All I ask is enough money for return postage. Too see if you are having this problem do the following using SDR. Disconnect the 37 pin connector and press the "1" key and then the "C" key. After a few seconds note the minimum / maximum counts from the A/D converter. If you have a 16 bit A/D chip and the min/max count is greater then +-8 the modification may help. With a 12 bit A/D chip the min/max counts should'nt be higher then +-2. -Larry Cochrane Redwood City, PSN At 11:44 PM 7/4/00 -0500, Angel wrote: > >Hi, > >I just got me new computer and much to my chagrin now all four of the >traces on SDR are much noisier. Little spikes, jus ta few counts. When I turn off the >new computer the noise goes away and when turn it on the noise comes >back. Obviously one solution is to not turn on the computer. Are there >any others? > > >Best regards, > Angel mailto:angel@............ > > >__________________________________________________________ > >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: 4 June M7.8 Sumatra Earthquake recorded by PSN From: Edward Cranswick cranswick@........ Date: Wed, 05 Jul 2000 02:10:52 -0600 PSN- Just for drill, I put together all the PSN records (all records displayed have been decimated to 0.5 sps or less) of the 4 June M7.8 Sumatra Earthquake http://wwwneic.cr.usgs.gov/neis/bulletin/00_EVENTS/000604162825/000604162825.HTML on one pseudo-recordsection; see ftp://groundmotion.cr.usgs.gov/PSN/event/Sumatra/ PLOT0001.GIF PLOT0002.GIF Low-passed at 0.1 Hz PLOT0003.GIF Low-passed at 0.01 Hz PLOT0004.GIF Low-passed at 0.02 Hz I then did some plots of Meredith's 3-component (vector) records of this event (all three components have been decimated to 0.5555 sps and are plotted at the same amplitude scale): PLOT0005.GIF PLOT0006.GIF Low-passed at 0.01 Hz PLOT0007.GIF Jump first 200 s, plot next 1000 s, low-passed at 0.1 Hz PLOT0008.GIF Jump first 200 s, plot next 1000 s, low-passed at 0.05 Hz PLOT0009.GIF Jump first 200 s, plot next ~10000 s, low-passed at 0.08 Hz PLOT0010.GIF Jump first 200 s, plot next ~10000 s, low-passed at 0.04 Hz PLOT0011.GIF Jump first 200 s, plot next ~10000 s, low-passed at 0.02 Hz PLOT0012.GIF Jump first 200 s, plot next ~10000 s, low-passed at 0.01 Hz Note the differences in amplitudes between the three components for different phases, different frequency bands. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: "Mark Robinson" other@............... Date: Wed, 5 Jul 2000 23:10:54 +1200 Power supplies are quite cheap (or free if you have a junk box like mine handy) ... try a few different ones ... It may also be worth while making up a separate plus and minus 12 volt regulated non switch mode power supply for the analogue parts of the electronics. I do this in computers where I need to get clean audio in and out. Mark ----- Original Message ----- From: "Larry Cochrane" To: Sent: Wednesday, 5 July 2000 18:04 Subject: Re: noisy power supply > Angel and others having this problem, > > I have noticed this problem with some motherboards. This happens on newer > motherboards that have switching power supplies that place a lot of high > frequency noise onto the + and/or - 12 volt supply lines. This noise gets > into the multiplexor chip and op-amp on the A/D card. > > About two months ago I started adding two inductors to my A/D card that > filters out the problem. The modifications are easy too make, but require > some soldering skills. I will create a web page that documents the changes > needed to add the inductors if anyone wants to modify their board. Just > about any small inductor will work as long as the DC resistance is only a > few ohms. If you don't have a supply of inductors at hand I can send you > two if you send me > an envelope with return postage. > > If your not into soldering you can send me your A/D board and I will make > the modifications for free. All I ask is enough money for return postage. > > Too see if you are having this problem do the following using SDR. > Disconnect the 37 pin connector and press the "1" key and then the "C" key. > After a few seconds note the minimum / maximum counts from the A/D > converter. If you have a 16 bit A/D chip and the min/max count is greater > then +-8 the modification may help. With a 12 bit A/D chip the min/max > counts should'nt be higher then +-2. > > -Larry Cochrane > Redwood City, PSN > > At 11:44 PM 7/4/00 -0500, Angel wrote: > > > >Hi, > > > >I just got me new computer and much to my chagrin now all four of the > >traces on SDR are much noisier. Little spikes, jus ta few counts. When I > turn off the > >new computer the noise goes away and when turn it on the noise comes > >back. Obviously one solution is to not turn on the computer. Are there > >any others? > > > > > >Best regards, > > Angel mailto:angel@............ > > > > > >__________________________________________________________ > > > >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: noisy power supply From: CapAAVSO@....... Date: Wed, 5 Jul 2000 09:20:35 EDT In a message dated 7/5/00 7:12:13 AM Eastern Daylight Time, other@............... writes: << It may also be worth while making up a separate plus and minus 12 volt regulated non switch mode power supply for the analogue parts of the electronics. I do this in computers where I need to get clean audio in and out. >> Dual plus and minus power supplies (non-switching) are easily made from parts all of which are usually in stock at your local Radio Shack. Buy two 12.6-volt transformers, Two full-wave bridge rectifiers, Two 1000 mfd electrolitic capacitors, Two 12-volt positive regulators and two 0.1 mfd capacitors. Build two separate 12-volt power supplies and hook them in series to make a +12V, -12V dual power supply. Radio Shack sells a little book about power supplies which you should also buy if you are not sure how to hook the above stuff together. With the help of the little book anybody can build their own dual power supply for far less than an off-the-shelf dual supply would cost. Have fun, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: John Hernlund hernlund@....... Date: Wed, 05 Jul 2000 14:29:02 -0700 (MST) On Tue, 4 Jul 2000, Angel Rodriguez wrote: > I just got me new computer and much to my chagrin now all four of the > traces on SDR are much noisier. Little spikes, jus ta few counts. When I turn off the > new computer the noise goes away and when turn it on the noise comes > back. Obviously one solution is to not turn on the computer. Are there > any others? > Best regards, > Angel mailto:angel@............ Angel, We often have these problems in our labs. I have an inelegant solution to this problem. I take aluminum foil, cover both sides in paper and tape it shut and wrap it around the data recording portion of the cards. It completely eliminates noise...but it looks like hell. John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: noisy power supply From: Angel Rodriguez angel@............ Date: Wed, 5 Jul 2000 22:33:54 -0500 Hello John, Wednesday, July 05, 2000, 4:29:02 PM, you wrote: JH> We often have these problems in our labs. I have an inelegant solution to JH> this problem. I take aluminum foil, cover both sides in paper and tape it JH> shut and wrap it around the data recording portion of the cards. It JH> completely eliminates noise...but it looks like hell. The new computer that is causing the problem is not even one of the the seismo computers, it's just on the same network. It's an NT machine that routes between my local network and the network that I get my Internet signal from. I had to make an 2.4 ghz link to my house since the nearest phone line is 6 miles away. From your suggestion I assume that it might be that the noise is coming the the air as RF interference. I will try to make some more shielding as you suggest. I have a new 3 component broadband that I have kludged into Larry's board. It's flat between 23 second and 40 Hz. I post the PSN files on an FTP at 200.46.19.178 anonymous no password. For now I have only been collecting data but I hope to start some sort of long term project. If you have any ideas please let me know. I am trying to make the leap between seismometry and seismology. My interest run towards local events since the network run by the University of Panama probably can't see events much below 2.5 Md. Warmly, angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: noisy power supply From: Angel Rodriguez angel@............ Date: Wed, 5 Jul 2000 22:57:44 -0500 Hello CapAAVSO, Wednesday, July 05, 2000, 4:20:35 AM, you wrote: Cac> In a message dated 7/5/00 7:12:13 AM Eastern Daylight Time, Cac> other@............... writes: Cac> << It may also be worth while making up a separate plus and minus 12 volt Cac> regulated non switch mode power supply for the analogue parts of the Cac> electronics. I do this in computers where I need to get clean audio in and Cac> out. >> Cac> Dual plus and minus power supplies (non-switching) are easily made from Cac> parts all of which are usually in stock at your local Radio Shack. Buy two Cac> 12.6-volt transformers, Two full-wave bridge rectifiers, Two 1000 mfd Cac> electrolitic capacitors, Two 12-volt positive regulators and two 0.1 mfd Cac> capacitors. Build two separate 12-volt power supplies and hook them in series Cac> to make a +12V, -12V dual power supply. Radio Shack sells a little book about Cac> power supplies which you should also buy if you are not sure how to hook the Cac> above stuff together. With the help of the little book anybody can build Cac> their own dual power supply for far less than an off-the-shelf dual supply Cac> would cost. Cac> Have fun, Cac> Cap Cac> __________________________________________________________ Cac> Public Seismic Network Mailing List (PSN-L) Cac> To leave this list email PSN-L-REQUEST@.............. with Cac> the body of the message (first line only): unsubscribe Cac> See http://www.seismicnet.com/maillist.html for more information. Hi, I have some -+ 12 volt supplies I have made for other projects. Where should I make the connections?? Do you suggest cutting and splicing the main power connector that goes to the ATX mother board?? This my first ATX computer and it seems that the power is switch on and off a bit differently than on an AT computer. The power off is just a software thing. -- Best regards, Angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: "Charles R. Patton" charles.r.patton@........ Date: Wed, 05 Jul 2000 21:54:05 -0700 I=92ll toss in my two bits. A new computer I purchased last Christmas tore up my wife=92s AM radio listening. The solution was to add an additional AC line filter on the outside of the computer. This was because the switching power supply on the inexpensive off-brand PC switching power supply did not have adequate filtering on the AC line side and the switching noise was radiating throughout the whole house. So you might want to explore that possibility. It sounds as if you=92re picking up some sort of radiated noise. Your LAN connection generally uses isolated transformer coupling and shouldn=92t be able to significantly radiate. Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: McWilliams Magnetometer From: The Lahrs johnjan@........ Date: Thu, 06 Jul 2000 08:15:56 -0600 Hi Cap, I received the information you sent me on the McWilliams magnetometer. Would it be OK if I posted this information on my web page? If so, how would I credit the design and the text? My parents live in Brookfield, CT. It would be fun to get together the next time I visit, which will probably be next November. I would love to see all of your instruments. I'm also interested in K-12 education, science fairs, etc. and agree with your posting a while back that if kids get into building their own instruments they will learn more about science than by any other means. Cheers, John >>. If you or anyone else would like a copy a Solar Bulletin that describes the McWilliams magnetometer in detail with drawings and a schematic of the Wheatstone bridge, just send a self addressed envelope to me at my address below and I'll be glad to send you a copy. The photocell displacement transducer might also work quite well on a seismograph. Casper H. Hossfield PO Box 23 New Milford, NY 10959 John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 john@........ http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re[2]: noisy power supply From: CapAAVSO@....... Date: Thu, 6 Jul 2000 10:56:10 EDT In a message dated 7/6/00 12:01:48 AM Eastern Daylight Time, angel@............ writes: << I have some -+ 12 volt supplies I have made for other projects. Where should I make the connections?? Do you suggest cutting and splicing the main power connector that goes to the ATX mother board?? This my first ATX computer and it seems that the power is switch on and off a bit differently than on an AT computer. The power off is just a software thing. -- Best regards, Angel mailto:angel@............ >> Hi Angel, The power supplies I described in my email of 07/05/00 made from radio shack parts are described again below: << Dual plus and minus power supplies (non-switching) are easily made from parts all of which are usually in stock at your local Radio Shack. Buy two 12.6 Volt transformers, two full-wave bridge rectifiers, two 1000 mfd electrolytic capacitors, two 12-volt positive voltage regulators and two 0.1 mfd capacitors. Build two separate 12-volt power supplies and hook them together in series to make a +12V, -12V dual power supply. Where they connect together goes to ground. Radio Shack sells a little book about power supplies which you should also buy if you are not sure how to hook the above stuff together. With the help of the little book anybody can build their own dual power supply for far less than an off-the-shelf dual supply would cost.>> These are two separate power supplies not connected to each other in any way, although they can be side by side on the same circuit board. Their outputs are floating, that is, isolated and not connected together as would be the case if you used one center tapped transformer and a negative voltage regulator. Connect the floating minus output of one power supply to the floating plus output of the other power supply. The point where the two connect together should then be connected to ground or neutral in whatever device they provide power for. The other two outputs provide the plus 12V and minus 12V to power the device. A dual + and - 5V supply can be made from two 6.3 Volt transformers and two plus 5 Volt regulators. The reason for using two transformers and two positive voltage regulators is Radio Shack does not carry negative voltage regulators. The above is a way to make one trip to Radio Shack and come home with everything you need to make a good homemade regulated dual power supply for far less money than you could buy a ready made one. I have never gotten into the guts of my computer so I think I should let someone else explain the details of just how to go about connecting the above dual power supply into your computer. Best regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: Karl Cunningham karlc@....... Date: Thu, 06 Jul 2000 07:56:32 -0700 another couple of cents: The isolation transformers used in network cards are good at isolating computers on different ground systems, but aren't very good at filtering out high-frequency noise. This noise can be conducted from one computer through the network cable to the other computer, or radiated from the cable. You might try looping the network cable through a ferrite toroid core several times so that the start and finish ends of the winding are opposite each other on the core. Then experiment with different locations and numbers of these ferrite cores on the network cables. A similar scheme significantly helped interference I had between one of my computers and WWVB reception. -- Karl At 09:54 PM 7/5/2000 -0700, Charles wrote: >Your LAN connection generally >uses isolated transformer coupling and shouldn’t be able to >significantly radiate. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: John Hernlund hernlund@....... Date: Thu, 06 Jul 2000 12:09:09 -0700 (MST) On Wed, 5 Jul 2000, Angel Rodriguez wrote: > The new computer that is causing the problem is not even one of the the > seismo computers, it's just on the same network. It's an NT > machine that routes between my local network and the network that I > get my Internet signal from. I had to make an 2.4 ghz link to my house > since the nearest phone line is 6 miles away. > > From your suggestion I assume that it might be that the noise is > coming the the air as RF interference. I will try to make some more > shielding as you suggest. Yes, the RF is usually my problem. We are attempting to make electrical conductivity measurements of mantle materials at high temperature and pressure (in a multiple-anvil device). Since most of this stuff has a low conductivity, we are usually interested in measurements in the kohm-Mohm range. Because the resistances are high, the current generated by our measurements is low, so lends itself to more variation in the ratio V/I. We heat our samples using resistance furnaces and up to 800 W of power, which generates a huge amount of noise. This problem is amplified by the neighboring labs which do secondary ion mass spectroscopy, nuclear magnetic resonance, etc.. We have to shield virtually everything to get a reasonable signal. > I have a new 3 component broadband that I have kludged into Larry's > board. It's flat between 23 second and 40 Hz. I post the PSN files > on an FTP at 200.46.19.178 anonymous no password. > > For now I have only been collecting data but I hope to start some sort > of long term project. If you have any ideas please let me know. I am > trying to make the leap between seismometry and seismology. My > interest run towards local events since the network run by the > University of Panama probably can't see events much below 2.5 Md. > Warmly, > angel You can do a lot with a single station I think. One of the first things I'd try is to measure the P-S converted waves from the moho and the offset time between them, which will give you a depth to the discontinuity beneath the station. The way it works is that a portion of the P-waves coming up transfer their energy into S-waves along with a continued P-wave. The S-wave motion will have to be in-line with the radial direction back to the focus, which confines your search for waveforms in the three components. The vertical record will show a strong P arrival, and then shortly after the P-S converted wave will be seen in the horizontal record. Using knowledge of the two different velocities then, you can find the depth to the moho. This is usually what a lot of the wiggles soon after the first P arrival account for: the noise and reverberations and conversion of the first wave to other phases at discontinuities. Another fun thing to try is to find SS and PP precursors, which are phases that don't bounce off the surface but rather bounce off the discontinuities at 660, 410, and the moho. Because the PP and SS come in after bouncing at the surface these will arrive a little sooner. This will give you depths to discontinuities at points in between the epicenter and your station. Many seismologists are doing both of these types of studies these days, and some are producing maps of the global variations of the discontinuity depths. With an array, you can get a bunch of different mid-points and study the region in more detail...it will be interesting to see what comes out of the upcoming USArray in this kind of study; should be pretty hot. If you have access to a research library, see if you can browse through the Bulletin of the Seismological Society of America (BSSA) which has a lot of interesting articles and different techniques you can apply to seismic data. The seismology stuff is really very easy and simple, but the knowledge you can obtain about the inner Earth with it is pretty cool. Good luck! John Hernlund E-mail: hernlund@....... WWW: http://www.public.asu.edu/~hernlund/ ****************************************************************************** __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: ChrisAtUpw@....... Date: Thu, 6 Jul 2000 21:18:24 EDT In a message dated 05/07/00 05:48:05 GMT Daylight Time, angel@............ writes: > I just got me new computer and much to my chagrin now all four of the > traces on SDR are much noisier. Little spikes, jus ta few counts. When I > turn off the > new computer the noise goes away and when turn it on the noise comes > back. Obviously one solution is to not turn on the computer. Are there > any others? Two quick thoughts. Have you checked that the Earth connection to your power socket really IS Earth and it's resistance? Second, it's a new computer and it is giving problems --- COMPLAIN and demand that the shop get it fixed. Why should YOU have to solve the problem? Regards, Chris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: noisy power supply From: Angel Rodriguez angel@............ Date: Sat, 1 Jan 2000 04:34:25 -0500 Hello Chris, Thursday, July 06, 2000, 4:18:24 PM, you wrote: Cac> In a message dated 05/07/00 05:48:05 GMT Daylight Time, angel@............ Cac> writes: >> I just got me new computer and much to my chagrin now all four of the >> traces on SDR are much noisier. Little spikes, jus ta few counts. When I >> turn off the >> new computer the noise goes away and when turn it on the noise comes >> back. Obviously one solution is to not turn on the computer. Are there >> any others? Cac> Two quick thoughts. Have you checked that the Earth connection to your Cac> power socket really IS Earth and it's resistance? Second, it's a new computer Cac> and it is giving problems --- COMPLAIN and demand that the shop get it fixed. Cac> Why should YOU have to solve the problem? Cac> Regards, Cac> Chris Cac> __________________________________________________________ Cac> Public Seismic Network Mailing List (PSN-L) Cac> To leave this list email PSN-L-REQUEST@.............. with Cac> the body of the message (first line only): unsubscribe Cac> See http://www.seismicnet.com/maillist.html for more information. Hi Chris, You should come to Panama and try to return anything! Oh well, living here does have many advantage but returning things isn't one of them. I can hardly get most things! I do know that my Earth connections are not the greatest, but I'm not sure what to do about it. I have a wire going from the equipment rack to a ground rod. The AC power comes from an inverter that is about 75 feet away and also has a ground rod. From the inverter I get the AC via two wires, (no ground wire. The computers and power supplies to the seismos are powered by the inverter (modified sine wave). The monitors and non-essential stuff is powered from the gird and that does have a ground wire that I assume goes to a ground rod, quite possibly the same on the inverter is tied to. The power goes out for more than an hour at least once a week and every day there are dropout that last from a few milliseconds to a second. Clean power is also not one of the thing you live here for! I'm open to any grounding suggestions, I have considered just running a big copper wire to everything and to a central ground rod. Regards, Angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: ELF precursor From: Arie Verveer ajbv@............ Date: Fri, 07 Jul 2000 11:59:36 +0800 Hi, In the Larry's "Earthquake data files"; 000706a.au4 is an event file that has another tantalizing trace of the background ELF/ULF data. It may be the quake from the Aleutians? Interesting thing to contemplate. I probable won't post any more files of this nature (ELF) on this site. Unless its very big. Charlie Plyler site at http://www.elfrad.com is the place for ELF/ULF seismic precursor info. Arie. -------------------------------------------------------------------- The following is from the United States Geological Survey, National Earthquake Information Centre: preliminary hypocenter for earthquake of 2000 jul 06, NEAR ISLANDS, ALEUTIAN ISLANDS, about 125 miles (200 km) W of Attu, Alaska: latitude 53.2 degrees north longitude 170.2 degrees east origin time 06 15 27.5 utc depth normal, magnitude 5.5 mb. ..com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: "Al Allworth" allworth@.............. Date: Thu, 6 Jul 2000 22:37:12 -0700 Have you tried a large ferrite suppressor bead or two on the power cord? Some are split and clamped around the cord near the power supply. _______________________________ Al Allworth On the Beautiful Southern Oregon Coast ________________________________ ----- Original Message ----- From: To: Sent: Thursday, July 06, 2000 6:18 PM Subject: Re: noisy power supply > In a message dated 05/07/00 05:48:05 GMT Daylight Time, angel@............ > writes: > > > I just got me new computer and much to my chagrin now all four of the > > traces on SDR are much noisier. Little spikes, jus ta few counts. When I > > turn off the > > new computer the noise goes away and when turn it on the noise comes > > back. Obviously one solution is to not turn on the computer. Are there > > any others? > > Two quick thoughts. Have you checked that the Earth connection to your > power socket really IS Earth and it's resistance? Second, it's a new computer > and it is giving problems --- COMPLAIN and demand that the shop get it fixed. > Why should YOU have to solve the problem? > > Regards, > > Chris > __________________________________________________________ > > 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[2]: noisy power supply From: Angel Rodriguez angel@............ Date: Fri, 7 Jul 2000 19:32:28 -0500 Hello Al, Friday, July 07, 2000, 12:37:12 AM, you wrote: AA> Have you tried a large ferrite suppressor bead or AA> two on the power cord? Some are split and AA> clamped around the cord near the power supply. I'm going to Seattle latter this month and various ferrite cores along with some small inductors and some Radio Shack things are on the shopping list. The only electronic parts I can get are those used to repair TV's and VCR's, :-) it's real limiting some times. -- Best regards, Angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: BOB BARNS roybar@........ Date: Fri, 07 Jul 2000 10:12:17 -0400 Al, Your mention of ferrite supperssors reminded me that I once reduced high freq. noise from a computer by placing a (split) ferrite block around the cable connecting the keyboard to the computer. Bob Al Allworth wrote: > > Have you tried a large ferrite suppressor bead or > two on the power cord? Some are split and > clamped around the cord near the power supply. > _______________________________ > > Al Allworth > > On the Beautiful Southern Oregon Coast > > ________________________________ > ----- Original Message ----- > From: > To: > Sent: Thursday, July 06, 2000 6:18 PM > Subject: Re: noisy power supply > > > In a message dated 05/07/00 05:48:05 GMT Daylight Time, angel@............ > > writes: > > > > > I just got me new computer and much to my chagrin now all four of the > > > traces on SDR are much noisier. Little spikes, jus ta few counts. > When I > > > turn off the > > > new computer the noise goes away and when turn it on the noise comes > > > back. Obviously one solution is to not turn on the computer. Are > there > > > any others? > > > > Two quick thoughts. Have you checked that the Earth connection to your > > power socket really IS Earth and it's resistance? Second, it's a new > computer > > and it is giving problems --- COMPLAIN and demand that the shop get it > fixed. > > Why should YOU have to solve the problem? > > > > Regards, > > > > Chris > > __________________________________________________________ > > > > 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: Re[2]: noisy power supply From: SW6079@....... Date: Fri, 7 Jul 2000 10:14:38 EDT Hi Angel........ Read your post. I just picked up a mess of Hi mu ferrites (not the split type, you'd have to splice the wire) for a hi power RF amp I'm working on. I'd be happy to send you a few no charge. Mike SW6079@....... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: McWilliams Magnetometer From: CapAAVSO@....... Date: Fri, 7 Jul 2000 10:28:32 EDT In a message dated 7/6/00 10:18:05 AM Eastern Daylight Time, johnjan@........ writes: << I received the information you sent me on the McWilliams magnetometer. Would it be OK if I posted this information on my web page? If so, how would I credit the design and the text? >> Hi John, OK to put the McWilliams magnetometer article on your web page. Credit it to the September 1998 issue of the Solar Bulletin which is published by the American Association of Variable Star Observers, AAVSO. It is simple easy-to-build instrument that is suitable as a science fair project and yet it is sensitive and accurate enough to make recordings of magnetic storms that are duplicates of those made by nearby USGS magnetic stations. It's hard to tell the difference. Next time you travel to Connecticut let me know and I'll draw you a map how to find my farm and we can enjoy a good visit. I live way back in the woods on a mountain. Best regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: Jan Froom Froom@............. Date: Fri, 07 Jul 2000 07:36:26 -0700 Everyone has been talking about power supply noise... but a monitor in video mode probably puts out more noise than anything else. You might want to boot that other computer up in DOS mode and see if you still have the problem. I'm not sure if the video noise comes from the video card or monitor, but it definitely comes on strong when in the video mode. Jan... Everyone has been talking about power supply noise... but a monitor in video mode probably puts out more noise than anything else. You might want to boot that other computer up in DOS mode and see if you still have the problem. I'm not sure if the video noise comes from the video card or monitor, but it definitely comes on strong when in the video mode.

Jan...
 
  Subject: Re: McWilliams Magnetometer From: "J. D. Cooley" jdcooley@............. Date: Fri, 07 Jul 2000 07:59:22 -0700 At 10:28 AM 7/7/00 EDT, you wrote: [snip] > I live way back in the woods on a mountain. > >Best regards, >Cap That explains a lot!! Just kidding Cap, "JD" P.S. For those that don't get the joke, it is an old line. When someone says "I fell on my head when I was a child." You say, "That explains a lot!" "JD" __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: noisy power supply From: SW6079@....... Date: Fri, 7 Jul 2000 11:06:40 EDT If you can stand yet another post.... I just remembered a problem that I had that was very similar. It was caused by the interactions between the modified sine-wave of the inverter and the switching power supply used by the equipment I was using. I solved it finally with an isolation transformer between the two. Most likely this simply acted as a choke, dampening the switching transients. Two identical transformers connected back to back with enough VA would likely serve as well. Good Luck, Mike. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re[2]: noisy power supply From: Karl Cunningham karlc@....... Date: Fri, 07 Jul 2000 14:34:07 -0700 Angel -- Another thing for your shopping list might be copper strap -- 3 or 4" wide. It is available in some amateur radio or marine radio shops, sometimes marine hardware stores. It's used to provide a good ground for radios on fiberglass boats, but makes good grounding strap in any case. Use it to connect the chassis of various parts of your system together, and to whatever earth connections are the best -- metal water pipes, antenna tower bases, ground rods, etc. Karl At 07:32 PM 7/7/2000 -0500, you wrote: >I'm going to Seattle latter this month and various ferrite cores along with some small >inductors and some Radio Shack things are on the shopping list. The >only electronic parts I can get are those used to repair TV's >and VCR's, :-) it's real limiting some times. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: McWilliams Magnetometer From: CapAAVSO@....... Date: Fri, 7 Jul 2000 17:35:57 EDT In a message dated 7/7/00 11:00:17 AM Eastern Daylight Time, jdcooley@............. writes: << [snip] "I live way back in the woods on a mountain". <> Gee, Thanks, JD, for the "compliment" !! What it explains, actually, is I'm an amateur astronomer and bought the farm on top of the mountain for its dark skies. Now that I'm retired I live here and can go outside any clear night and see the Milky Way in all its glory. And the floor of my basement is bedrock to set my seismometer on !! It's nice and peaceful out here and I don't miss the town where I lived most of my life one bit !! Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: McWilliams Magnetometer From: "Raul J. Alvarez" ralvarez@........ Date: Fri, 07 Jul 2000 15:36:27 -0600 Hi Cap, Was just reading the mail and was about to write the exact words! I also live back in the woods and up a mountain - just on the other side of the country - the Rockies!! Retirement is GREAT! Raul CapAAVSO@....... wrote: > In a message dated 7/7/00 11:00:17 AM Eastern Daylight Time, > jdcooley@............. writes: > > << [snip] > > "I live way back in the woods on a mountain". > > <> > > Gee, Thanks, JD, for the "compliment" !! > > What it explains, actually, is I'm an amateur astronomer and bought the > farm on top of the mountain for its dark skies. Now that I'm retired I live > here and can go outside any clear night and see the Milky Way in all its > glory. And the floor of my basement is bedrock to set my seismometer on !! > It's nice and peaceful out here and I don't miss the town where I lived most > of my life one bit !! > > Cap > __________________________________________________________ > > 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: noisy power supply From: Mark Robinson other@............... Date: Sat, 08 Jul 2000 11:32:32 +1200 Angel, Do I remember correctly that you said that evil word "inverter" ? Do you still get the noise if you run straight off the mains without the inverter ? regards Mark -- Mark G Robinson | ZL2TOD | other@............... ------------------------------------------------ 07 Jul 1479 Leonardo da Vinci is acquitted of homosexuality. 07 Jul 1852 Sir Arthur Conan-Doyle died. 07 Jul 1858 Central Auckland suffers a serious fire. 07 Jul 1916 The New Zealand Labour Party is formed at a meeting in Able Smith Street Wellington. 07 Jul 1919 Jon Pertwee born. 07 Jul 1924 A patent is granted for the self winding watch. 07 Jul 1940 Ringo Starr born. 07 Jul 1941 Bill Oddie born. 07 Jul 1952 Superliner "United States" wins Blue Riband trophy for record Atlantic crossing of 3 days, 10 hours and 40 minutes. 07 Jul 1960 The invention of the laser is announced. 07 Jul 1965 The World licking record is set using 296,872 stamps. 07 Jul 1966 Cpt born. 07 Jul 1968 TThe Yardbirds broke up. Jimmy page formed The New Yardbirds to fulfil concert obligations. The name was c __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re[2]: noisy power supply From: Angel Rodriguez angel@............ Date: Sat, 8 Jul 2000 07:13:53 -0500 Hello Mark, Friday, July 07, 2000, 6:32:32 PM, you wrote: MR> Angel, MR> Do I remember correctly that you said that evil word "inverter" ? MR> Do you still get the noise if you run straight off the mains without the MR> inverter ? MR> regards MR> Mark Hi Mark et. al, Well to be honest I too think that "inverters" are evil, but when power goes out as often as it does here it is a necessary evil. I have been working off-list with Chris and one of the first things he asked me to do was to take the new computer off the inverter and presto things cleared up. Things are actually cleaner now than they have ever been. I still think the problem is complex and many of the suggestions and hintscarla59 will lead me to a clean, well ground system that is non-mains dependent. I have two PSU's that are AT and connect directly of 12 volts, but the new computer is, of course, ATX. AT one point I was going to get rid of the inverter and make the entire system 12 volts. I may still yet because the company makes am ATX variant. Angel mailto:angel@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re[2]: noisy power supply From: Mariotti Mauro mariottim@...... Date: Sun, 09 Jul 2000 09:06:09 +0200 Be careful when you choice a point to wire the ground. If you use a water pipe, for example, you may risk, if accidentally a 110V power supply line (or here in Europe 220V power supply line) touch for a moment the ground wire you will find one phase of the AC current onto your water pipe system! And if your electric plant it is not protected with a differential interruptor it could be the cause of the DEAD os someone. I think is better to provide a GOOD ground discharge point with planting a copper rod of 1.5 .. 2 mt directly in the ground. If a technician do this it's better. About noise I think this is the main problem of amateur seismologist, due the equipments are very sensitive to electromagnetic fields. Pay attention with ground loops, shielded cables, and circuitry metal cases. In some occasions metal cases induced more disturbances rather than the plastic ones due ground loops caused by metal case to copper pour of the pcb looped again on the metal case and so on with shielded cables that link one board to the next. One counsil to apply is: 1. Place your horizontal sensors in stable position rollin them to one side, the pendulum will set at right or left without oscillate. 2. Lock the mass of your vertical sensor. 3. Now set you gain amplfier to the maximum. 4. watch the chart of SDR of other acquisition prgram 5. if you see the trace moving up and down slowly or quickly be sure that what you se it is'nt a seismic signal. 6. So you can start to make experiments and reduce this noise that surely is electromagnetic noise, 7. after this you can set up again your sensors and you will see the most clean trace you never see before Sincerely Mauro Mariotti At 14.34 07/07/2000 -0700, you wrote: >Angel -- > >Another thing for your shopping list might be copper strap -- 3 or 4" wide. > It is available in some amateur radio or marine radio shops, sometimes >marine hardware stores. It's used to provide a good ground for radios on >fiberglass boats, but makes good grounding strap in any case. > >Use it to connect the chassis of various parts of your system together, and >to whatever earth connections are the best -- metal water pipes, antenna >tower bases, ground rods, etc. > >Karl > > >At 07:32 PM 7/7/2000 -0500, you wrote: >>I'm going to Seattle latter this month and various ferrite cores along >with some small >>inductors and some Radio Shack things are on the shopping list. The >>only electronic parts I can get are those used to repair TV's >>and VCR's, :-) it's real limiting some times. > >__________________________________________________________ > >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: AS1 Seismic System From: The Lahrs johnjan@........ Date: Sun, 09 Jul 2000 07:56:54 -0600 I'm running an AS1 seismic system in my basement to get some experience with it prior to showing it to the teachers attending an Exploratorium workshop the last week of July and the First week of August. For a preliminary look at this turn-key system, see: http://lahr.org/john-jan/psn/as1/as1.html Cheers, John John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 john@........ http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: McWilliams Magnetometer From: CapAAVSO@....... Date: Sun, 9 Jul 2000 10:24:10 EDT In a message dated 7/7/00 5:41:28 PM Eastern Daylight Time, ralvarez@........ writes: << Was just reading the mail and was about to write the exact words! I also live back in the woods and up a mountain - just on the other side of the country - the Rockies!! Retirement is GREAT! >> Hi Raul, Probably other amateur scientists would choose our good life too if they knew about propane powered refrigerators and how easy it is to run all your stuff with a small generator and some batteries. Running your own phone line from the main road is not difficult either. Too bad most people don't seem to know about these things. Best regards, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: active filters From: BOB BARNS roybar@........ Date: Sun, 09 Jul 2000 11:59:18 -0400 Hi gang, ebay has a Kron-Hite filter, ebay#376944839. Can't tell what the specs are. I use a Rockland dual tuneable filter with my Lehman -- works great! One is avail. at: http://216.87.163.91/cgi-bin/dinamic/link.cfm?ID=219310&Dealer_ID=43&web_site=http://www.kentronix.com/ for $250 incl. manual. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: AS1 Seismic System From: Stephen Mortensen mortskm@....... Date: Sun, 09 Jul 2000 11:08:27 -0700 The Lahrs wrote: > > > For a preliminary look at this turn-key system, see: > http://lahr.org/john-jan/psn/as1/as1.html > > Cheers, > John > John C. Lahr > 1925 Foothills Road > Golden, CO 80402 > (303) 215-9913 > john@........ > http://lahr.org/john-jan/science.html Question,,,, I checked the AS1 site above and was interested in the filter that extends the response of the 1.5 natural period to 20 sec,,,,,, How would it be configured to do that???? I spent a couple of hours trying to find the answer in the PSN archives and found a separate add on but didn't notice any add on on the simple diagram or photos of the AS1. For the moment I'm using an STM-8 without the feedback,,,, simple coil and magnet and oil damping,,, it has a natural period of about 4 to 5 seconds. It would be interesting to see if I can extend the response to 20 or 30 seconds with a filter,, until I get the force feedback built. Is the coil in an active filter loop,,,, etc?? Can someone point me to a schematic, a link, an archive,,, etc for the way it could be configured and how would you determine the part values for a given period?? Thanks in advance Stephen Mortensen PSN Station #55 near Pilot Hill Ca 38.828N 120.978W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: noisy power supply From: Angel Rodriguez angel@............ Date: Mon, 10 Jul 2000 02:22:38 -0500 Hi All, Just a note to thank Chris, Mike and Larry and all the others that helped so much with what started as a noisy ATX PSU and turn out to be completely inadequate grounds and as one person put it an "evil" inverter and the noisy PSU. I may have been pushing the inverter past it's limits. My station is now about 20% quieter that the time of my first post. And when I'm done I hope it will be lots quieter and here are some of the thing I am gong to do. Rework the house and system grounds so that it all converges at a single point. Better ground my equipment rack and all the computer cases. Move away from the "evil" inverter and have everything that needs to survive a prolonged lack of grid power be on my 12v DC system. Install suppressors on all things hooked to the mains especially if they were purchased in Panama and that are not labeled with an EC or FCC rf compliance certification. As I began to unplug Panama purchased components things got quieter. Power supplies in local computer weight half as much as the US bought power supplies and are lots noisier. That was a great observation the Chris made, I would not have though that it would have made so much difference! Install the inductors on Larry's board. Thanks again to all and suggestion are still always welcome! Angel __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Feedback analyzer From: Brett Nordgren bnordgren@.............. Date: Mon, 10 Jul 2000 16:55:07 -0400 To the feedback seismo designers: Check out They are selling Bafco model 911A2D Frequency Response Analyzers. These cover a frequency range of 0.01 hz - 10 khz. The analyzer generates a test signal at its output and then tunes for that exact frequency return-signal at the input terminals. Digital readout is in db amplitude and degrees phase of the measured signal vs the output signal. Should be perfect for checking out low frequency feedback systems (feedback seismometers). They want $275 plus priority mail shipping from Las Vegas (was $47 to New Jersey). Originally these were several thousand dollars. Mine appears to have not been un-packed since it was shipped to the Navy in 1991, and came complete with manual and all accessories. If this is within your budget and you're serious about building feedback seismo's you might want to have a look. Good luck, Brett __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: New Event From: barry lotz gbl@....... Date: Mon, 10 Jul 2000 18:39:58 -0700 Looks like a new event is coming in from the Alaska area. Red Puma: 11Jul2000 01:32:27.3 57.6N 154.5W 56 MW=6.5 M*NEI KODIAK ISLAND REGION 0229 11Jul2000 01:32:18.9 56.2N 153.0W 0 mb=6.3 M*MAD KODIAK ISLAND REGION 0222 11Jul2000 01:32:54.6 61.9N 150.8W 10 M >6.5 A*SED SOUTH Looks like a new event is coming in from the Alaska area. Red Puma:

11Jul2000 01:32:27.3 57.6N 154.5W 56 MW=6.5 M*NEI KODIAK ISLAND REGION      0229
11Jul2000 01:32:18.9 56.2N 153.0W  0 mb=6.3 M*MAD KODIAK ISLAND REGION      0222
11Jul2000 01:32:54.6 61.9N 150.8W 10 M >6.5 A*SED SOUTH Subject: inverters From: S-T Morrissey sean@........... Date: Tue, 11 Jul 2000 13:47:39 -0500 (CDT) I am concerned about the bad rap being laid on inverters to provide uninterruptible and possibly precision AC power. As with any device, there are good designs and there are boxes of compromises that can cause problems. If an inverter is causing more problems than it is solving, it needs to be replaced with a better unit, especially one that has a reserve capacity. I have consistently used inverters to power seismic systems, and several are currently in use at SLU to operate both the analog and the digital systems, including several SUN workstations. These are of the totally uninterruptible design, without any switching to the inverter in the event of an outage: the loads operate continuously from the 1 kilowatt precision inverters, which operate on either 12 or 24 Volt, 200 or 100 ampere supplies, which are connected in parallel with 660 ampere hour battery systems. The "12" volts is actually adjusted to the critical cell voltages of the Lead-Calcium cells, which are warranted for 20 years. I used similar systems at Adak, AK, in the Aleutians. The AC power from the navy was from diesel generators, about the reliability of Angel's. Our systems could operate for at least 6 hours from the batteries, but we also had our own 15 kW diesel backup generator with enough fuel for weeks. The frequency control of the AC power was so poor that ferroresonant (CVT) regulators (constant voltage transformers, or CVTs) were useless, so we used 1.5kw servo controlled variacs to control the line voltage. For frequency dependent mag tape and continuous microfilm recorders, the Topaz inverters had crystal controlled stability. For efficiency, these large inverters synthesized a sine wave output. For the IRIS stations, we use switched-mode, microprocessor controlled inverters by BEST. They provide only line conditioning in normal mode, but sense a brownout within 1 cycle of the AC line and switch in the inverter, starting it with perfect synchronism; the return of the load to the AC line is similarly synchronized with the zero crossing of the sine wave. (Their main weakness is that they sense a "low battery" condition and shut down the inverter to protect the battery, but then continue to run the microprocessor from the battery, which eventually kills it AND the program/memory backup lithium cells if the outage lasts longer than a day. I had to install Hg relays to disconnect the batteries if neither the line or the inverter voltages were present). Their charger program can be adjusted for the capacity of additional external batteries. Similar technology is used in their better (transformer based) PC level UPS boxes of a few hundred watts, such as I have at home, but without access to the microprocessor program. They are not, however designed for long term continuous use, mainly because of inadequate cooling. But a less expensive "sort-of" square-wave output inverter can be a problem. The better ones still use a large transformer, and will run continuously at about 50% of their rating, But some really lightweights use a totally switched mode system to get 110VAC with lots of noise. I have a large transformer coupled one in my field van, and the square wave even messes with the electronic speed control of some VSR drills. The frequency is stabilized, though, so for some electronic applications I use a CVT which cleans up the square wave into a sine wave. As always, the good, the bad, and the ugly of it is that you get what you pay for, so a good initial investment is worth considering. And as with any power switching device, a good design does include proper transient suppression and shielding/grounding. Surprisingly, a significant radiator of noise are the DC input cables, which often are not by-passed with capacitors and isolated with torroid inductors. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: inverters: a question for Sean From: SW6079@....... Date: Tue, 11 Jul 2000 20:31:31 EDT I sure agree w/ you on the less-expensive inverters (transformerless type). I've never 'scoped the output from a CV xfmer while driven by an inverter. Is it really a pure sine? If so, it gives me a few ideas for a situation I'll be facing next year. Thanks, Mike. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: inverters From: ChrisAtUpw@....... Date: Tue, 11 Jul 2000 22:33:01 EDT In a message dated 11/07/00 19:48:48 GMT Daylight Time, sean@........... writes: > I am concerned about the bad rap being laid on inverters to provide > uninterruptible and possibly precision AC power. > As with any device, there are good designs and there are boxes of > compromises that can cause problems. We may not all know what to look for in the advertising blurb and some manufacturers seem very silent about minor details like waveforms and frequency stability. When does 'modified sine wave' = troublesome square wave of no discernable stability or power? > As always, the good, the bad, and the ugly of it is that you get what > you pay for, so a good initial investment is worth considering. > And as with any power switching device, a good design does include proper > transient suppression and shielding/grounding. Surprisingly, a significant > radiator of noise are the DC input cables, which often are not by-passed > with capacitors and isolated with toroid inductors. Yup. My experience:- The shiny new box with brightly coloured knobs is clearly labelled 'no user servicable parts inside' and comes without a circuit diagram. This is 'confidential information' according to the salesperson, who seems to take the production of an adjustable spanner and a cross head screwdriver as a mortal insult..... > I have consistently used inverters to power seismic systems...., > These are of the totally uninterruptible design, without any switching > to the inverter in the event of an outage: the loads operate continuously > from the 1 kilowatt precision inverters, which operate on either > 12 or 24 Volt, 200 or 100 ampere supplies..... Which might cause the love of my life to make some very terminal remarks..... Is there a well suppressed, crystal controlled, sine wave inverter / charger unit of ~200 W continuous rating that won't make a glaringly obvious hole in my monthly paycheck, please? Regards, Chris __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: inverters: a question for Sean From: Brian Chesire BCChesire@................ Date: Tue, 11 Jul 2000 19:35:33 -0700 I missed the begining of this thread, but have the following comments: If CV is a constant voltage transformer, the output is a Square Wave. There are two types of constant voltage transfomers, the standard CV and the harmonic neutralized "CVN". The CVN puts out a low distortion sine wave. Brian Tucson, AZ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: constant voltage transformers From: S-T Morrissey sean@........... Date: Wed, 12 Jul 2000 14:44:29 -0500 (CDT) Regarding constant voltage transformers, or CVTs. I have been using them for over 30 years, and have always found a sinewave output. There are some better designs that use a larger high voltage AC capacitor for the resonant circuit that are "harmonic neutralized" and regulate to 1% over a +,- 20% input change. These cost about 10% to 20% more than the 3% regulation "line conditioners", which DO put out a sinewave, but with higher distortion. The very nature of CVT design is that it is a true transformer (total isolation of the input from the output), that only passes a sinewave to the output winding at the resonant frequency of the high voltage secondary/capacitor circuit. If you play with one with a variac (variable transformer) input, you can see this: as you increase the input, there is little output until there is enough voltage (about 45 volts AC) to resonant the high voltage secondary, at which point the output jumps to within a few percent of the regulated level. As you drop the input voltage, to as low as 20 VAC, the output remains near 110V as long as the transformer resonants (test with a moderate load, like a lightbulb). SOLA is a major manufacturer, and they claim that their standard conditioners (MCR series) will output a sinewave with 3% THD (total harmonic distortion) with a square wave input. I use a 120 watt CVT with my large frequency controlled converter in my field van to convert the square wave to a sine wave for electronic loads. This is similar to common marine use for AC operated electronics. Since CVTs are passive, they last a long time; the main problem being the high operating temperature of the transformer core that eventually cooks the insulation, and the high voltage (660 volt) AC capacitors that eventually fail causing a voltage drop. The capacitors are replaceable. Since CVTs ONLY pass a completely isolated sinewave, I have always used them as a primary protection of the AC line from lightning. They always work, except in one case when the lightning arced thruout the case to the secondary line. I have had one at a shared tower facility where lightning has frequently smoked the varistor-based line protection of the other equipment, while the seismic station and transmitter were never harmed. They are an expensive ($350 for 250 watts) but permanent solution for protecting AC loads. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Obsolete I.C. needed From: "Al Allworth" allworth@.............. Date: Wed, 12 Jul 2000 13:10:47 -0700 Hi All, Do any of you know where one could find a Motorola or equivalent MC3420 or MC3520? I know there are some suppliers of obsolete I.C.s but have lost access to the sources I used before retiring. I need one for a power supply. Thanks, Al _______________________________ Al Allworth W7PXX On the Beautiful Southern Oregon Coast ________________________________ ----- Original Message ----- From: "S-T Morrissey" To: Sent: Wednesday, July 12, 2000 12:44 PM Subject: constant voltage transformers > > Regarding constant voltage transformers, or CVTs. > > I have been using them for over 30 years, and have always found > a sinewave output. There are some better designs that use a > larger high voltage AC capacitor for the resonant circuit that > are "harmonic neutralized" and regulate to 1% over a +,- 20% > input change. These cost about 10% to 20% more than the 3% regulation > "line conditioners", which DO put out a sinewave, but with higher > distortion. The very nature of CVT design is that it is a true > transformer (total isolation of the input from the output), that > only passes a sinewave to the output winding at the resonant > frequency of the high voltage secondary/capacitor circuit. > > If you play with one with a variac (variable transformer) input, > you can see this: as you increase the input, there is little > output until there is enough voltage (about 45 volts AC) to resonant > the high voltage secondary, at which point the output jumps to within > a few percent of the regulated level. As you drop the input voltage, > to as low as 20 VAC, the output remains near 110V as long as the > transformer resonants (test with a moderate load, like a lightbulb). > > SOLA is a major manufacturer, and they claim that their standard > conditioners (MCR series) will output a sinewave with 3% THD (total > harmonic distortion) with a square wave input. I use a 120 watt CVT > with my large frequency controlled converter in my field van to > convert the square wave to a sine wave for electronic loads. This > is similar to common marine use for AC operated electronics. > > Since CVTs are passive, they last a long time; the main problem being > the high operating temperature of the transformer core that eventually > cooks the insulation, and the high voltage (660 volt) AC capacitors that > eventually fail causing a voltage drop. The capacitors are replaceable. > > Since CVTs ONLY pass a completely isolated sinewave, I have always > used them as a primary protection of the AC line from lightning. They > always work, except in one case when the lightning arced thruout the > case to the secondary line. I have had one at a shared tower facility > where lightning has frequently smoked the varistor-based line protection > of the other equipment, while the seismic station and transmitter were > never harmed. They are an expensive ($350 for 250 watts) but permanent > solution for protecting AC loads. > > Regards, > Sean-Thomas > __________________________________________________________ > > 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: Obsolete I.C. needed From: "Raul J. Alvarez" ralvarez@........ Date: Wed, 12 Jul 2000 15:11:05 -0600 Hi Al, I show some (20) in my personal stock. I will have to search as I have never resorted them after my move to Colorado. I will look in the next few days and get back to you. Raul Alvarez Al Allworth wrote: > Hi All, > > Do any of you know where one could find a Motorola or equivalent MC3420 > or MC3520? I know there are some suppliers of obsolete I.C.s but have > lost access to the sources I used before retiring. I need one for a power > supply. > > Thanks, Al > _______________________________ > > Al Allworth W7PXX > > On the Beautiful Southern Oregon Coast > > ________________________________ > ----- Original Message ----- > From: "S-T Morrissey" > To: > Sent: Wednesday, July 12, 2000 12:44 PM > Subject: constant voltage transformers > > > > > Regarding constant voltage transformers, or CVTs. > > > > I have been using them for over 30 years, and have always found > > a sinewave output. There are some better designs that use a > > larger high voltage AC capacitor for the resonant circuit that > > are "harmonic neutralized" and regulate to 1% over a +,- 20% > > input change. These cost about 10% to 20% more than the 3% regulation > > "line conditioners", which DO put out a sinewave, but with higher > > distortion. The very nature of CVT design is that it is a true > > transformer (total isolation of the input from the output), that > > only passes a sinewave to the output winding at the resonant > > frequency of the high voltage secondary/capacitor circuit. > > > > If you play with one with a variac (variable transformer) input, > > you can see this: as you increase the input, there is little > > output until there is enough voltage (about 45 volts AC) to resonant > > the high voltage secondary, at which point the output jumps to within > > a few percent of the regulated level. As you drop the input voltage, > > to as low as 20 VAC, the output remains near 110V as long as the > > transformer resonants (test with a moderate load, like a lightbulb). > > > > SOLA is a major manufacturer, and they claim that their standard > > conditioners (MCR series) will output a sinewave with 3% THD (total > > harmonic distortion) with a square wave input. I use a 120 watt CVT > > with my large frequency controlled converter in my field van to > > convert the square wave to a sine wave for electronic loads. This > > is similar to common marine use for AC operated electronics. > > > > Since CVTs are passive, they last a long time; the main problem being > > the high operating temperature of the transformer core that eventually > > cooks the insulation, and the high voltage (660 volt) AC capacitors that > > eventually fail causing a voltage drop. The capacitors are replaceable. > > > > Since CVTs ONLY pass a completely isolated sinewave, I have always > > used them as a primary protection of the AC line from lightning. They > > always work, except in one case when the lightning arced thruout the > > case to the secondary line. I have had one at a shared tower facility > > where lightning has frequently smoked the varistor-based line protection > > of the other equipment, while the seismic station and transmitter were > > never harmed. They are an expensive ($350 for 250 watts) but permanent > > solution for protecting AC loads. > > > > Regards, > > Sean-Thomas > > __________________________________________________________ > > > > 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: Your web site. From: The Lahrs johnjan@........ Date: Wed, 12 Jul 2000 22:15:41 -0600 Hi Cap, I put the McWilliams Magnetometer article on this web page: http://lahr.org/john-jan/earth_science/magnetometer/ Let me know if you seen any problems with it. Which issue of the Solar Bulletin was it in? Cheers, John At 11:02 AM 7/11/00 , you wrote: >Hi John, > I checked your excellent web site to see if I could refer someone to it >who is interested in building a McWilliams Magnetometer. As it is now I have >to send them photocopies of Jim Mandaville's article in the Solar Bulletin by >snail mail. Besides his magnetometer Jim also has a "whistler Receiver" that >is simple to build and would be very suitable to build as a science fair >project. Whistlers are a natural phenomenon that originate in the >magnetosphere where the magnetic storms occur so both can be projects to >learn about the geophysics of the Earth's magnetosphere. We are approaching >solar maximum when whistlers and magnetic storms are both plentiful. Are you >interested in whistlers and would you like to add the whistler receiver to >your science projects? >Best regards, >Cap * John C. and Jan H. Lahr *JohnJan@........ * 1925 Foothills Road * Golden, Colorado 80401-1718 * (303) 215-9913 * http://lahr.org/john-jan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: constant voltage transformers From: SW6079@....... Date: Thu, 13 Jul 2000 03:57:26 EDT Tnx for the reply, Sean. I've used them in various apps too. Around here I've gotten "defective" ones cheap, replaced the caps, and saved a bundle. Can't wait to try 'em with a square wave. Later, Mike. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: AmaSeis program From: The Lahrs johnjan@........ Date: Thu, 13 Jul 2000 07:32:10 -0600 I've checked with Alan Jones and IRIS and the AmaSeis program will be made available free of charge for anyone to use. The beta version can be obtained here: http://www.geol.binghamton.edu/faculty/jones/as1.html John John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 john@........ http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re:ground rods and noisy power supplies From: "Charles R. Patton" charles.r.patton@........ Date: Thu, 13 Jul 2000 10:36:04 -0700 I wanted to make one additional comment regarding ground rods in general. It=92s very important NOT to use multiple rods in an installation. Not only does it add ground current noise as has already been mentioned, but it is a safety issue as well. In particular if you have a lightning strike in the vicinity, the ground currents become enormous, and so the voltage drop across the ground and thereby the voltage across the ground rods can be very large, and depending on the distance between them can be thousands of volts. We=92re not talking miles here, just feet. So if your equipment has connected grounds, suddenly opposite ends of your equipment are connected to a very powerful, high voltage source which causes large currents to flow, melting cables and of course, frying the attached electronic equipment. And the big point is, not only can it fry equipment, it can electrocute you. If you used multiple ground rods, but the grounds aren=92t connected, then the problem becomes the high voltages placed on the AC isolation means, i.e., the primary of the AC line transformers suddenly have to withstand huge voltages, again with the same result, breakdown and fried equipment. Within a single installation, use only a single point ground rod, and then provide a ground strapping/connection grid that acts as a reference =93plane=94 for your system. Try to insulate th= e outlying sensors and bring their grounds back to your central system or else use total galvanic isolation which is a whole another subject in itself. A good idea on the insulated outlying systems is to provide lightning strike protection. A good example is the telephone system. They use carbon blocks separated by a thin mica sheet with holes in it or gas tubes from each line to the ground rod at the entrance to the house. These are very high impedance devices until they breakdown, at which point they can carry large discharge currents. I don=92t remember now, but I believe Sean-Thomas talked about some seismo equipment inside PVC pipe that took a lightning hit. Not a pretty description! Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re:ground rods and noisy power supplies From: "Al Allworth" allworth@.............. Date: Thu, 13 Jul 2000 11:23:54 -0700 Hello All, An interesting fact: Some areas REQUIRE multiple ground electrodes on the power system. The state of Oregon electrical codes require at least 2 ground rods spaced at least 8 feet apart. The conductor connecting the rods to the system must be continuous and must run from one rod to the other and then to the the service box. The rods must be at least 8 feet long but can be driven at an angle in shallow soil. Extra grounds for individual equipment are not covered by these requirements. _______________________________ Al Allworth On the Beautiful Southern Oregon Coast ________________________________ ----- Original Message ----- From: "Charles R. Patton" To: ; "Charles R. Patton" Sent: Thursday, July 13, 2000 10:36 AM Subject: Re:ground rods and noisy power supplies I wanted to make one additional comment regarding ground rods in general. It's very important NOT to use multiple rods in an installation. Not only does it add ground current noise as has already been mentioned, but it is a safety issue as well. In particular if you have a lightning strike in the vicinity, the ground currents become enormous, and so the voltage drop across the ground and thereby the voltage across the ground rods can be very large, and depending on the distance between them can be thousands of volts. We're not talking miles here, just feet. So if your equipment has connected grounds, suddenly opposite ends of your equipment are connected to a very powerful, high voltage source which causes large currents to flow, melting cables and of course, frying the attached electronic equipment. And the big point is, not only can it fry equipment, it can electrocute you. If you used multiple ground rods, but the grounds aren't connected, then the problem becomes the high voltages placed on the AC isolation means, i.e., the primary of the AC line transformers suddenly have to withstand huge voltages, again with the same result, breakdown and fried equipment. Within a single installation, use only a single point ground rod, and then provide a ground strapping/connection grid that acts as a reference "plane" for your system. Try to insulate the outlying sensors and bring their grounds back to your central system or else use total galvanic isolation which is a whole another subject in itself. A good idea on the insulated outlying systems is to provide lightning strike protection. A good example is the telephone system. They use carbon blocks separated by a thin mica sheet with holes in it or gas tubes from each line to the ground rod at the entrance to the house. These are very high impedance devices until they breakdown, at which point they can carry large discharge currents. I don't remember now, but I believe Sean-Thomas talked about some seismo equipment inside PVC pipe that took a lightning hit. Not a pretty description! Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ground rods and noisy power supplies From: cplyler cplyler@............. Date: Thu, 13 Jul 2000 15:10:28 -0400 Hello All, Power substations also require multiple ground rods. I believe the issue is to make sure that when using multiple ground rods, they should all tie in to one point. Then make only one connection to your equipment to that point. Charlie Plyler Al Allworth wrote: > > Hello All, > > An interesting fact: Some areas REQUIRE multiple ground electrodes on the > power system. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re:ground rods and noisy power supplies From: ted@.......... Date: Thu, 13 Jul 2000 15:28:36 -0400 We just upgraded our home electrical service from 60 amp to 200 amp, put in new meters, new breaker box, and so on. Code now requires that the meter box be separately grounded outsided the house via its own ground wire (bare copper stranded, very heavy maybe #4?) to two six-foot copper rods in a daisy-chain arrangement. Driving these was a chore - they don't call this the Granite state for nothing. This is in addition to the normal ground to the water pipe inside the house. Could this lead to the same kind of voltage drop you mentioned? Regards, Ted Blank __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ground rods and noisy power supplies From: Bob Smith bobsmith5@........ Date: Thu, 13 Jul 2000 18:16:19 -0400 My experience was similar to Ted's. I built a major addition to my home two years ago. It required a major (read - expensive) electrical upgrade replacing a 200 Amp meter base with 350 Amp system. The old "cold water pipe" ground system was cut out and replaced with two eight foot, galvanized rods driven at least three foot apart and connected to the meter box neutral bond point with #4 AWG bare copper wire. I also have another eight foot ground rod back at my amateur radio room which serves for lightning protection and noise ground but it does not connect to the electrical system neutral in accordance with local codes which permit only a single point ground to the electrical system at the entrance panel(s). Incidently, the preferred ground rod for heavy duty service around here is not copper, but galvanized steel - eight foot long by about 3/4" diameter. To drive them in the local soil which is hard, yellow clay (sometimes called 'hardpan'), about the consistency of soft sandstone) one takes a Coke bottle of water and jabs the rod into the soil(?) a few inches, fill the hole with water and keep jabbing. Bob Smith ted@.......... wrote: > > We just upgraded our home electrical service from 60 amp to 200 amp, put in > new meters, new breaker box, and so on. Code now requires that the meter > box be separately grounded outsided the house via its own ground wire (bare > copper stranded, very heavy maybe #4?) to two six-foot copper rods in a > daisy-chain arrangement. Driving these was a chore - they don't call this > the Granite state for nothing. > > This is in addition to the normal ground to the water pipe inside the > house. > > Could this lead to the same kind of voltage drop you mentioned? > > Regards, Ted Blank > > __________________________________________________________ > > 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. -- --------- Avoid computer viruses -- Practice safe hex ------------- * * Specializing in small, cost effective embedded control systems * * Robert L. (Bob) Smith Smith Machine Works, Inc. internet bobsmith5@.............. Lumlay Road landline 804/745-1065 Richmond, Virginia 23236+1004 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: book by bullen From: BOB BARNS roybar@........ Date: Thu, 13 Jul 2000 20:43:56 -0400 Hi gang, "Intro. to the Theory of Seismology" by Bullen is up for auction on ebay, #380647856, ends 7/19, no bids so far. Paperback. Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ground rods and noisy power supplies From: "Charles R. Patton" charles.r.patton@........ Date: Fri, 14 Jul 2000 11:51:35 -0700 The responses re the use of multiple ground stakes daisy-chained back to a single point on the house are fine. If high current flows, it will only be between the ground stakes, not between pieces of your equipment. As another bit of information, on USA systems, there is a ground from the neutral on the transformer at the power pole. So there could be large voltages and currents in the neutral leg and thereby superimposed on the AC line. The protection here is the circuit breaker panel at the entrance to the house and the ground rod at the house. I have not looked at the current NEC codes, but the use of multiple ground stakes in a daisy-chain makes sense. A big problem with ground stakes is keeping their resistance low. Techniques have included pouring salt solutions such as copper sulphate (bad for the environment), sodium or calcium chloride (still not much better for the environment in the concentrations needed) in the ground with them or even making special rods which weep salt solutions. The use of the plumbing as a ground was a two edged sword. The connection was good because it typically has many feet buried in the ground, but the galvanic corrosion can eat up the pipes and if the connection was bad and there was a ground fault, the plumbing goes =93hot=94 with possible consequences of electrocution. Like so many things, at first glance it seems simple, but there can be many ramifications as you dig into it. One way to kind of look at it is the Faraday cage. If the ground system you make is a grid or cage like thing, then even it the ground rod goes up in voltage, you are enclosed in a zero volt environment. This falls to pieces when a wire extends through that cage to the outside world. Then you bring in whatever is outside. Hence my discussion of carbon blocks or gas protector on sensor lines to your remote seismometer equipment. Complete isolation is becoming more feasible today. There are low current op-amps and serial output, high accuracy A/D=92s that can= be easily connected to fiber optic transmission links. So the power requirements on the sensor side can be made quite low and supplied by a fiber optic link. Combine that with a fiber optic link information return, and your sensor combination can be made immune to millions of volts -- pretty safe, even from lightning strikes. Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Foils for hinges From: ChrisAtUpw@....... Date: Fri, 14 Jul 2000 18:51:21 EDT I note that K & S Metals have added 2 thou Stainless Foil to their collection of brass and other foils. See http://www.ksmetals.com/ then click on foils. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: AS1 Performance From: The Lahrs johnjan@........ Date: Sun, 16 Jul 2000 18:36:59 -0600 Hi Bob, I've finished putting the AGU talk on the AS1 onto my web site: http://lahr.org/john-jan/psn/as1/as1_resp/ Thanks for providing the figures. John At 10:36 AM 7/14/00 , you wrote: >John - I am trying to reconstruct the .ps files now. I have some of them, >others I may have to re-run. I'll try to get these done today, but if I >don't, what's your deadline? > > Bob Hutt > >At 07:11 AM 7/14/00 , you wrote: >>Hi Bob, >> >>I've decided to put the entire performance article that you wrote on the >>web, as >>it's a good example for the PSN folks of how a system is analyzed. The >>text is here: >>http://lahr.org/john-jan/psn/as1/as1_resp/index.html >>now, and I would like to take you up on digital versions of the >>figures. Are they >>in PostScript format? >> >>Thanks! >>John >>John C. Lahr >>lahr@........ (work) >>john@........ (home) >> >>Central Region Geologic Hazards Team >>U.S. Geological Survey >>PO Box 25046 >>Denver, CO 80225 John C. Lahr 1925 Foothills Road Golden, CO 80402 (303) 215-9913 john@........ http://lahr.org/john-jan/science.html __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Web Ring From: The Lahrs johnjan@........ Date: Sun, 16 Jul 2000 18:42:34 -0600 I'm surprised more people haven't joined the PSN web ring! To join, just fill in your URL here: http://dominicapsn.freeyellow.com/joinring.html This could be a very convenient way for people to find all of the various PSN web sites. Cheers, John * John C. and Jan H. Lahr *JohnJan@........ * 1925 Foothills Road * Golden, Colorado 80401-1718 * (303) 215-9913 * http://lahr.org/john-jan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Another geomagnetic storm from the sun From: meredith lamb mlamb1@.......... Date: Mon, 17 Jul 2000 10:27:22 -0700 Hi all, Noted another couple spikes from a geomagnetic storm on the 13th of July 2000. This is from my diamagnetic "seismo", (which I should probably call a quasi-seismo/magnetometer). It sometimes detects seismic waves, and solar flare disturbances, but seemingly only if its NOT shielded (?). See, the bottom of: http://www.geocities.com/meredithlamb/page054.html Included is a imported (but hard to read) GIF image of the geomagnetic USGS.gov image of the BOU (Boulder, Colorado) for that day. Simply a fun detail note. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: ELF precursor From: meredith lamb mlamb1@.......... Date: Tue, 18 Jul 2000 11:03:19 -0700 Arie Verveer wrote: > Hi, In the Larry's "Earthquake data files"; 000706a.au4 is an event > file that has another tantalizing trace of the background ELF/ULF data. > It may be the quake from the Aleutians? Interesting thing to contemplate. > I probable won't post any more files of this nature (ELF) on this site. > Unless its very big. Charlie Plyler site at http://www.elfrad.com is the > place for ELF/ULF seismic precursor info. > > Arie. > > -------------------------------------------------------------------- > The following is from the United States Geological Survey, National > Earthquake Information Centre: preliminary hypocenter for > earthquake of 2000 jul 06, NEAR ISLANDS, ALEUTIAN ISLANDS, about 125 > miles (200 km) W of Attu, Alaska: latitude 53.2 degrees north > longitude 170.2 degrees east origin time 06 15 27.5 utc depth > normal, magnitude 5.5 mb. > .com/maillist.html for more information. Hi Arie and everyone, Actually, EMF precursors are known to exist and this aspect I find very interesting to read, see any graphs on. The problem seems to be the reliablity of continiously being able to do so repeatably....but this be just the earth natures with location and size of the quake area it affects, and also the individual sensor location. For myself, anything unusual, is more attention getting than the normal understood items.....so.....keep it up, its nice to see. Thanks, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: The McWilliams Magnetometer and notes & ?'s From: meredith lamb mlamb1@.......... Date: Tue, 18 Jul 2000 11:27:17 -0700 The Lahrs wrote: > Hi Cap, > > I put the McWilliams Magnetometer article on this web page: > http://lahr.org/john-jan/earth_science/magnetometer/ > Let me know if you seen any problems with it. Which issue of the > Solar Bulletin was it in? > > Cheers, > John > > At 11:02 AM 7/11/00 , you wrote: > >Hi John, > > I checked your excellent web site to see if I could refer someone to it > >who is interested in building a McWilliams Magnetometer. As it is now I have > >to send them photocopies of Jim Mandaville's article in the Solar Bulletin by > >snail mail. Besides his magnetometer Jim also has a "whistler Receiver" that > >is simple to build and would be very suitable to build as a science fair > >project. Whistlers are a natural phenomenon that originate in the > >magnetosphere where the magnetic storms occur so both can be projects to > >learn about the geophysics of the Earth's magnetosphere. We are approaching > >solar maximum when whistlers and magnetic storms are both plentiful. Are you > >interested in whistlers and would you like to add the whistler receiver to > >your science projects? > >Best regards, > >Cap > Hi all, I note that the Forcefield/Wondermagnet web site has a relatively big (6" length, 1" width by 1/2" thick) ceramic (ferrite) magnet for sale for U.S. $5.50 each. 800 gauss. The flat surface maybe easier to work with than a round rod. Whether or not they are adequate for this application I don't know. I'd question whether a series of neodymium magnets could be better or worse than a item like this in comparison trials. One might even add on a neo or two on the ends of this, and see if it helps the sensitivity aspect? See: http://www.wondermagnet.com/dev/magnet26.html Meredtih Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: The McWilliams Magnetometer and notes & ?'s From: CapAAVSO@....... Date: Tue, 18 Jul 2000 18:54:20 EDT In a message dated 7/18/00 1:36:18 PM Eastern Daylight Time, mlamb1@.......... writes: << I note that the Forcefield/Wondermagnet web site has a relatively big (6" length, 1" width by 1/2" thick) ceramic (ferrite) magnet for sale for U.S. $5.50 each. 800 gauss. The flat surface maybe easier to work with than a round rod. Whether or not they are adequate for this application I don't know. I'd question whether a series of neodymium magnets could be better or worse than a item like this in comparison trials. One might even add on a neo or two on the ends of this, and see if it helps the sensitivity aspect? See: http://www.wondermagnet.com/dev/magnet26.html Meredtih Lamb >> Hi Meredith, I now realize, thanks to Chris Chapman, that using the Neodymium magnets from Wondermagnet was a mistake. Their temperature coefficient is very unfavorable compared to the Alnico magnets from Edmund Scientific that we have been using for many years to build McWilliams torsion balanced magnetometers. I am switching back to Alnico magnets which, although weaker, nevertheless provide adequate sensitivity. There was a very nice magnetic storm on 8 June that was very well recorded with homemade torsion balance magnetometers. The June Solar Bulletin shows how well these recordings compare to nearby US Geological Survey Magnetic Observatory magnetograms made with a professional fluxgate magnetometer. The June Solar Bulletin also has complete details on how to build your own homemade fluxgate magnetometer for about US$ 40. There is a schematic and parts list and four pages of interesting information on how the fluxgate works. If anyone would like to have a free copy of this Bulletin please send me a self addressed stamped envelope (no stamps if outside USA) at the address below. Best regards, Casper H. Hossfield PO Box 23 New Milford, NY 10959 USA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Check this From: "Ahmet Ercan" yeraltiaramaclk@............... Date: Wed, 19 Jul 2000 09:11:03 +0300 Have fun with these links. Bye. Subject: Re: Check this From: Stephen Mortensen mortskm@....... Date: Tue, 18 Jul 2000 23:49:05 -0700 Ahmet Ercan wrote: > Have fun with these links. > Bye. My Nortons anti virus just alerted me that this email had a trojan horse virus called Links2.VBS!!!!!!! DON'T OPEN IT!!!!!!!! Stephen Mortensen __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Check this From: "Mark Robinson" other@............... Date: Wed, 19 Jul 2000 20:38:17 +1200 Hello, Oi'm a virus from Ireland. Please forward this email to all the contacts in your personal address book, then delete all the files on your hard disk. Dat's grand Tanks very much! ----- Original Message ----- From: "Ahmet Ercan" To: Sent: Wednesday, 19 July 2000 18:11 Subject: Check this > Have fun with these links. > Bye. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Check this From: Karl Kolle kwk@.......... Date: Wed, 19 Jul 2000 10:06:20 +0100 (BST) Sorry ... but ??????? Who is 'Mark Robinson' ???????? Regards/Saludos/mit freundlichen Gruessen Karl ------------------------------------------------------------------ Karl-Wilhelm Kolle E-Mail: kwk@.......... Isaac Newton Group of Telescopes Tel : +34-22-405639 Royal Greenwich Observatory : +34-22-405655 Apartado de Correos 321 Fax : +34-22-405646 38780 Santa Cruz de La Palma _______ Isla San Miguel de La Palma/Canarias / \ Spain ______/ O \ / \ \ \_/ \ ..... and \ \ save \____ the \ Rottweilers !!! \ ------------------------------------------------------------------ On Wed, 19 Jul 2000, Mark Robinson wrote: > Hello, Oi'm a virus from Ireland. > Please forward this email to all the contacts in > your personal address book, > then delete all the files on your hard disk. > > Dat's grand > > Tanks very much! > > > ----- Original Message ----- > From: "Ahmet Ercan" > To: > Sent: Wednesday, 19 July 2000 18:11 > Subject: Check this > > > > Have fun with these links. > > Bye. > > __________________________________________________________ > > 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: Virus Warning From: "Mark Robinson" other@............... Date: Wed, 19 Jul 2000 22:27:21 +1200 I am Mark Robinson. Sorry - I intended to send that message to the unfortunate individual who sent that virus to the list, rather than to the whole list. Just a note : If you opened the attachment to Ahmet Ercan's message and you are running windows you may have rather a problem. My apologies Mark ----- Original Message ----- From: "Karl Kolle" To: Sent: Wednesday, 19 July 2000 21:06 Subject: Re: Check this > > > Sorry ... but > > ??????? Who is 'Mark Robinson' ???????? > > > Regards/Saludos/mit freundlichen Gruessen > > Karl > > ------------------------------------------------------------------ > Karl-Wilhelm Kolle E-Mail: kwk@.......... > Isaac Newton Group of Telescopes Tel : +34-22-405639 > Royal Greenwich Observatory : +34-22-405655 > Apartado de Correos 321 Fax : +34-22-405646 > 38780 Santa Cruz de La Palma _______ > Isla San Miguel de La Palma/Canarias / \ > Spain ______/ O \ / \ > \ \_/ \ > ..... and \ \ > save \____ > the \ > Rottweilers !!! \ > ------------------------------------------------------------------ > > > On Wed, 19 Jul 2000, Mark Robinson wrote: > > > Hello, Oi'm a virus from Ireland. > > Please forward this email to all the contacts in > > your personal address book, > > then delete all the files on your hard disk. > > > > Dat's grand > > > > Tanks very much! > > > > > > ----- Original Message ----- > > From: "Ahmet Ercan" > > To: > > Sent: Wednesday, 19 July 2000 18:11 > > Subject: Check this > > > > > > > Have fun with these links. > > > Bye. > > > > __________________________________________________________ > > > > 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.se