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Earthquake Detector
User-Contributed Project
This project guide is not managed by MAKE staff.
An earthquake detector with an experimental purpose.
- Author: Andrea
- Time required: 1 to 2 hours
- Difficulty: Easy
x 
x 4
An earthquake detector can be an useful home safety device, because It alerts you to a strong shaking some seconds before it happens. During an earthquake two kinds of waves are emitted from the centre: a small wave and a dangerous wave. The small wave is faster, so it is the first sign of the event (if your house is located some kilometres away from the centre).
An earthquake detector could also work in combination with other devices, such as a gas switch.
That device consists of an high sensitive lever, which is hooked to a spring. A weight is fixed at the end of the lever by a M8 screw (the lever should work with a frequency of about 2 HZ). When the sensor shakes, a M3 screw fixed on the lever will touch the horizontal spring, and it will close a delay off circuit which drives a piezoelectric bell.
Relevant parts
- plastic board, solid material, 15 millimetres in depth
- crooked plastic lever, about 120°, 10 centimetres in total length
- bearing (2), 4 - 9 millimetre in diameter
- bearing tickness (2), brassy (suggested but not required)
- View:
- Paginated
- Full width
Edit Step 1
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Earthquake Detector
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Make the holes on the plastic board: 3 millimetres in diameter for the springs anchor bolts (fix three M3 screws); 4 millimetres in diameter for the lever fulcrum (fix a M4 screw)
Make the bearing housing on both sides of the lever: drill 8 millimetres in diameter on full depth; 9 millimetres in diameter on the sides
Make the hole for the spring anchor bolt (M3 screw) on the lever.
Make the hole for the switch screw on the lever.
Fix a M8 screw with a weight (I used some screw nuts) at the end of the lever.
Edit Step 2 ¶
Fix the springs and the lever on the board (using self lock screw nuts)
Put a thickness on both bearings(I used a brassy thickness).
Do not force the M4 screw nut on the bearings, otherwise the lever will not be sensitive.
Connect a wire to the static anchor bolt of the lever spring.
Connect the moving anchor bolt of the lever spring to the switch screw (you'll see a red wire jumper).
Connect a wire to the horizontal spring.
Connect the free ends of the wires to a delay off bell circuit
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