Seismology in Pearland, Texas, USA
John Cole's Public Seismic Network Station
Mail comments to: John C. Cole
Click on the panorama for a larger version
My Amateur Radio(W5AUH), Television and Seismograph Station. Move the lower bar to the right for a
complete panorama of my hobby shack. Note the two chart recorders for recording earthquakes and the wall world map
for locating them. The wall paper is made of earthquake seismograms recorded on my chart recorders. I constructed
this large room behind my house. It includes a working bronze cannon, coffee bar and rest room.
More than 40 years ago I constructed this six-inch reflecting telescope after grinding and polishing
the six-inch f-8 mirror. I recently restored it and plan to use a video camera mounted on the eyepiece to show the
moon and planets on Amateur Television.
Above is a picture of W5VID and me during a contact on 70cm ATV. I am shown on the 13"monitor on the
right while transmitting on a PC Electronics 70cm ATV transceiver. W5VID is monitoring his own transmissions on a
10" TV (left) while taking a photograph with his digital camera. Frank, W5VID, who is also an amateur seismologist,
lives in Friendswood, Texas, 11 miles from my QTH. When an earthquake occurs Frank and I compare wave forms from the
earthquake that we are both recording.
Above is a picture taken of two TV monitors while W5VID is in contact with me on 70cm ATV. On the 10"
TV on the left W5VID is showing me the wave forms of an earthquake in progress being recorded on a chart recorder at
his home. Conversely on the 13" TV on the right I am showing W5VID the wave forms of the same earthquake in progress
as being recorded on a chart recorder at my home.
AMATEUR SEISMOLOGISTS/HAM RADIO OPERATORS MEET VIA ATV on THURSDAY, MAY 9, 2002.
John, W5AUH, of Pearland, Texas, and Al Hrubetz, W5QEE (far right), of Dallas, Texas, in W5AUH's shack confer with
Frank, W5VID, in Friendswood, Texas.
The "Long John" Vertical with 8' Pendulum
Close-up View
My friend Frank Cooper suggested that I make a vertical with an eight foot long pendulum---and I did.
Here it is. Frank also insisted that I name it the "Long John."
A rod is suspended from the ceiling followed by several home wound springs giving the
pendulum a total length of eight feet. This is a most unusual vertical because it is capable of detecting a broad
spectrum of seismic waves from background noise to about 30 seconds or so. It only takes a little filtering to emphasize
the long or short waves. It exhibits the characterics of both a vertical and a horizontal sensor. The upper view
shows the PCV pipe which keeps air currents from disturbing the pendulum. The lower view shows
the damping paddles in containers of 30w motor oil and a 16,000 turn coil suspended between the gaps of a
powerful magnet. The wooden box keeps air currents from disturbing the lower part of the pendulum.
My
Mini-Mini Lehman
I designed this very small Lehman Seismic Sensor and had a machinist make six copies. The results have been outstanding. I designed the Mini-Mini for use by public schools and colleges or by any amateur seismologist. One of the Mini-Mini's is being used by a high school in Louisiana and another by an individual in South America. A third has undergone extensive testing by Frank Cooper in Friendswood, Texas, and passed with flying colors. It is a tiny little fellow with a foot print no larger than two sheets of regular typing paper and is a pleasure to adjust. It includes a guitar tuning gear for wire adjustment that does away with the awkward turnbuckle. It requires just an occasional tweak to keep the pendulum centered. I designed the pendulum pivot with a ball bearing. This innovation enables the Mini Mini to maintain a period of 16 seconds or better. I use magnets from old speakers. Note the magnet "holder."
I have discovered a
simple way to lengthen the period of a Lehman pendulum --- as much as 30 seconds before encountering instability.
My method is to use a ball bearing at the pivot point of the boom (the pencil in the picture is for reference).
This method eliminates a major part of the friction.
Drill a hole in the boom slightly larger than the bearing. Put a little gel type super glue in the hole and insert the ball bearing.
The hard steel bolt head on which the boom rests is polished with #300 and #600 sandpaper. After the boom is placed on the bolt head, it remains firmly placed. It seems too simple to be true, but it works!
My
Carbide Roller Bearing Suspension Sensor
This new form of suspension has been installed in an 18-inch pendulum sensor with a 16k turn pick-up
coil. An 1/8" brass rod is used for suspension of the coil. The roller bearing is easy to use and adjust. The
convex to convex suspension is used on the upper and lower pivot points. I believe this type of carbide roller
bearing has less friction than any other type of mechanical pivot. By using carbide microscopic "dimpling" of the
pivot points will not occur as it does in other methods of suspension. The two convex surfaces at the upper pivot
point are pulled together by the mass at the end of the pendulum. The mass at the end of the pendulum holds the upper
pivot assumbly in place. Will this assembly have stability and stay in place? ABSOLUTELY I have never had an
assembly come loose during actual use. It may happen from time to time during adjustments.
View of the Upper and Lower Carbide Bearings
Upper Carbide Bearing Assembly
Lower Carbide Bearing Assembly
Click here for a larger image
SENSOR HOUSE (Home of my two seismic sensors)
The covers for the two seismic sensors with a north-south orientation.
The two sensors are shown after the covers have been removed.
The purpose of having two sensors with the same north-south orientation is to test the effectiveness of various size coil windings. At present the coil in the foreground has 14,000 turns and the coil in the background has 12,000 turns. I have found that the 14,000 turn coil produces approximately a 20% gain in detected signal. Note the double brass paddles immersed in cans of 30 weight motor oil. They are used to dampen the movement of the pendulums.
With my new(used)coil winding machine I can wind any coil size I desire.
A 16,000 turn coil wound with the coil winding machine. It is held with an aluminum holder.
The coil can be adjusted within the holder
Home page last modified: Monday, March 14, 2005