Case #100: William Noticed a Vibration

By: 
April 09, 2007

Like Jack Godell's coffee in "The China Syndrome," the fluid in William Grill's Seismic Detector reveals subtle vibrations. The entire detector is built around a laser pointer, a few hobby-type mirrors, a PIN photdiode, regulator and amplifier, enclosed in common PVC tubing and fittings. This simple and inexpensive combination makes this detector far more sensitive than Jack's coffee.

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"Seismic Detector" Parts List:

"Quarter-sized Temperature controller"
Amt Part Description Allied Part #
1 TLC2272CP Dual Op-Amp 735-0250
1 3318S-1-201 200 Ohm trim pot 754-0841
2 10K 1/8 w Resistor 895-0355
1 4.7K 1/8 w Resistor 895-0812
1 3.3K 1/8 w Resistor 895-0798
1 0.1" grid Perf Board, cut to ~2"x0.8" 237-0134
Other Parts:
1-UA78L02ACLP TO-226 2.6 volt Regulator
1-OPTEK OP906 PhotoDetector
1-Laser Pointer (see article text)
A/R-Assorted PVC tubing, O-rings and fittings;
Adhesive
2 Round mirrors or 1 mirror and 1 clear window (see article text)
Optional:
1-DATAQ DI-148U, DI-194RS or other A/D Converter Module or development kit w/software (see article text)

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