topics

AS1 Setup

IRIS Kansas City WorkshopSeptember 19-21, 2007

John Lahr (with Kay Wyatt)and portions from

“Seismology Instruction with AmaSeis” By Tammy K. Bravo & Anne M. Ortiz

Topics

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

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.

Bill Storm’s AS1 on a countertop at his Davis, CA, school

Rod Allen’s system on the floor of the DaVinci Academy, Elgin, Illinois

Dane Alexander at Mattawan, Michigan, with AS1 on floor below monitor

Kay Wyatt at the Kids Zone in Depoe Bay Oregon with the seismometer on a

specially built cabinet bolted to the floor

SOME ASSEMBLY REQUIRED

First, examine the pieces before you start

Tighten all of the screws and nuts to

eliminate any “play.”

Be sure to tighten the coil to the base plate of the seismometer by turning the screw clockwise. Thecoil should be upright, perpendicular to the base, and may require tightening and/or gentlebending to orient correctly. Tighten the bolt that holds the magnet to the boom arm.

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.

First, adjust the “sideways level” with the two screws nearest the mast.

Next, adjust the

“lengthwise level” with the screw

near the coil.

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.

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, it’s

sharp!

If the knife edge ever gets nicked, you can sharpen it with a

sharpening stone.

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 boom’s 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.

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.

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.

The knife edge may have to be offset to one side of the mast to center the magnet over the coil.

With a rat-tail file, make a grove in the base of the cover for the coil wires.

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 .

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.

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.

RCA plug 9 pin serial plug

Finally, plug the power cable into the wall. Your setup should look like this