AS1 Setup and Calibration IRIS NSTA Workshop November 12, 2005

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AS1 SetupIRIS Kansas City WorkshopSeptember
19-21, 2007John Lahr (with Kay Wyatt)and
portions fromSeismology Instruction with
AmaSeis By Tammy K. Bravo Anne M. Ortiz
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Topics

• Location of AS-1
• Some assembly required
• Free period
• Damping
• Washer calibration
• AmaSeis software basics

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Location of AS1

• Compromise between a site with little noise
  versus a site that allows students to see the
  instrument in operation.
• The noise is least in a basement with concrete
  foundation and increases with each floor above
  that.
• The floor is better than a table, but a solid
  table or bench may still work OK.

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Bill Storms AS1 on a countertop at his Davis,
CA, school
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Rod Allens system on the floor of the DaVinci
Academy, Elgin, Illinois
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Dane Alexander at Mattawan, Michigan, with AS1 on
floor below monitor
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Kay Wyatt at the Kids Zone in Depoe Bay Oregon
with the seismometer on a specially built cabinet
bolted to the floor
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SOME ASSEMBLY REQUIRED
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First, examine the pieces before you start
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Tighten all of the screws and nuts to eliminate
any play.
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Be sure to tighten the coil to the base plate of
the seismometer by turning the screw clockwise.
The coil should be upright, perpendicular to the
base, and may require tightening and/or
gentle bending to orient correctly. Tighten the
bolt that holds the magnet to the boom arm.
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Place the base of the seismometer on a level
surface. The base contains three leveling screws.
Use the bubble level and adjust the leveling
screws as needed. Level the base, first across
the short dimension and then along the long
dimension.
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First, adjust the sideways level with the two
screws nearest the mast.
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Next, adjust the lengthwise level with the
screw near the coil.
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Remove the bolt and washer on the center of the
boom. This was used for the older style oil
damping.
Next, attach the copper paddle which is used for
the newer style magnetic damping.
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Remove the tape from the knife-edge at the end of
the boom. Carefully clean and inspect the knife
edge and apply a thin coating of oil.Watch out,
its sharp!
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If the knife edge ever gets nicked, you can
sharpen it with a sharpening stone.
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One end of the spring should be already connected
to the upright support post. Attach the other end
of the spring to the boom. Position the booms
knife-edge into the slot on the support post. The
boom will rest at an angle. This is to be
expected and will not damage the boom.
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Adjust the level of the boom by adding or
removing washers and by sliding the level bubble
along the boom. Leave the level on the boom!
CAUTION Do not release the boom arm abruptly.
This will result in the magnet hitting the coil.
The equipment is sensitive handle and adjust the
parts carefully and gently.
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Center the magnet over the coil so that there is
space on both sides. This is critical! The boom
arm should move freely up and down, and the
magnet should not touch the coil.
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The knife edge may have to be offset to one side
of the mast to center the magnet over the coil.
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With a rat-tail file, make a grove in the base of
the cover for the coil wires.
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Attach the paired shielded coaxial cable to the
interface box by inserting the two exposed wires
one at a time to the posts. To attach a wire to a
post the wire must pass through the hole in the
post, then tighten the plastic knob. The wire
insulation must not enter the screw terminal, as
tightening the terminal cap may then not yield
good contact between the metal wire and the post
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The center conductor of the signal cable
(uninsulated wire) should be connected to the
ground terminal (black post) on the interface
box. The remaining two insulated wires should be
connected to the two red posts. Tighten until
snug.
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9 pin serial plug
RCA plug
Attach the RCA plug to the matching plug on the
seismometer. Then, attach the 9 pin plug to the
serial port on your computer. If you do not have
a serial port, you can buy an inexpensive adapter
so that it can plug into a USB port on your
computer.
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Finally, plug the power cable into the wall.
Your setup should look like this