Instructables is such a super source of information! A while back I was looking for
ideas for a seismometer I wanted to build and ran across the IBLs that used a piezo
element from a $1 intruder alarm as a microphone. There was my seismometer transducer.
What a deal for a buck!
A seismometer is a sensing device that detects movement of the earth's crust. These
movements are often called earthquakes when they are large enough to be felt. Since
there are not a lot of earthquakes you can feel in Georgia, I wanted a seismometer
that could detect even very small movements ("micro-quakes?").
This seismometer detects when there is a quake. The inertia of a weight suspended at
the end of a lever arm flexes the piezo element. This flexing generates a small
electrical current. That current is fed into the microphone jack on a computer or
digital recorder. Computer software then analyzes the results.
I use the term "seismometer" for the detector and the term "seismograph" for the
combined detector plus the analyzing/recording software. Some people use the term
"geophone" for the detector as the detector is an "earth microphone". I am not a
geologist so decide for yourself what terms you want to use.
There are a number of references in the last step that may help you with the project.
This might make a good science project if you live in a seismically active area.
There is a bit of soldering involved in this project, but it is otherwise pretty
simple. The cost should be $10-$15 and the software is free.
Step 1: Parts and Tools
From Dollar Tree (Pic 1)
myTunes 1/8" RCA plug audio cable - $1.00
Intruder Alert - $1.00
myTunes 1/8" audio extension cable - $1.00
1 Oz. Steel Egg Sinkers (fishing supplies) - $2
Panel-mount RCA jacks (RadioShack #274-346) $4
Tools and Supplies (Pic 2)
Drill with 3/16" and 1/4" bits
Wire coat hanger
10-24 X 5/8" nut and bolt pack (Lowes #62096) $1
A tall, narrow plastic jar about 6-8" tall by 2" or more in diameter
(a 28 oz peanut butter jar would work)
Optional parts from Lowes or Home Depot (See Step 5)
7/8" spade drill bit
5' of 2" PVC Thick-walled Pipe (Lowes) $5
2 each 2" test caps (Lowes #23406) $2
2 each 3/16" X 1 1/4" fender washer (Lowes #2576) $1
1 1/8" X 23/32" rubber grommet (Lowes #139378) $1