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Have you ever wanted to impress your friends by saying something crazy like, "I think there's going to be an earthquake soon" moments before an earthquake hits?
Or do you just want some warning, a few seconds that could save your life.
This project will allow you to hook up a seismic sensor to a router through the Ethernet shield and host a webpage off of the SD card on the shield. This webpage will then display information about the seismic sensor and the history of its activity.
All the data for the seismic sensor is stored in a Pachube feed and then displayed on the webpage as several graphs.
You will need:
- Arduino
- Preferably an Arduino with large memory, I used the Arduino Mega 2560
- You can use one with less memory, you just might have to remove some stuff from the sketch
- Ethernet Shield
- Micro SD Card
- Pachube account:
- Piezoelectric Sensor
- Breadboard
- Resistors, Capacitors, Diode
- Check the section on building the circuit for more details on values
- 5 x Op-Amps - Single-supply compatible
- or you can build it with dual supplies, whatever floats your boat :p
- You can get away with using only 3 - 4 op amps, the rest I use is for amplification
- Solid Wire of course!
I assume you already have:
- Router
- Computer
- Would be pretty magical to surf the net without these
- Extra Ethernet cable
- USB cable for the arduino
- Un-destroyed analog pin on your arduino
Or do you just want some warning, a few seconds that could save your life.
This project will allow you to hook up a seismic sensor to a router through the Ethernet shield and host a webpage off of the SD card on the shield. This webpage will then display information about the seismic sensor and the history of its activity.
All the data for the seismic sensor is stored in a Pachube feed and then displayed on the webpage as several graphs.
You will need:
- Arduino
- Preferably an Arduino with large memory, I used the Arduino Mega 2560
- You can use one with less memory, you just might have to remove some stuff from the sketch
- Ethernet Shield
- Micro SD Card
- Pachube account:
- Piezoelectric Sensor
- Breadboard
- Resistors, Capacitors, Diode
- Check the section on building the circuit for more details on values
- 5 x Op-Amps - Single-supply compatible
- or you can build it with dual supplies, whatever floats your boat :p
- You can get away with using only 3 - 4 op amps, the rest I use is for amplification
- Solid Wire of course!
I assume you already have:
- Router
- Computer
- Would be pretty magical to surf the net without these
- Extra Ethernet cable
- USB cable for the arduino
- Un-destroyed analog pin on your arduino
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Signing UpStep 1The Circuit - Sensor
The sensor I used to capture seismic vibrations is a Piezo Film vibra-tab.
They come with an optional weight attached to the end, but I found that the weight was not enough.
The frequency of earthquakes is between 1 - 20 Hz, but with even the heaviest weight the resonant frequency was in the KHz.
So to reduce the resonant frequency and get some useful signals, I took some washers slapped them on a bolt and some nuts and experimented. I used a Oscilloscope with FFT and changed the weight on the tip of the film until frequencies of around 40Hz were the largest. If you don't own an oscilloscope, just add a little weight and then hit the sensor. It should flop around for about half a second to a second before coming to rest.
Once you have the sensor tuned to the right frequency, place it in your breadboard at one end, you're going to need the space for the rest of the circuit.
As you can see from the picture, I taped down the base of the sensor. This is because the leads on the piezo film is flat, and tends to be loose inside the breadboard, so any vibrations tend to get lost in the movement of the leads.
Taping it so that the base can't move will ensure that your data is accurate!
They come with an optional weight attached to the end, but I found that the weight was not enough.
The frequency of earthquakes is between 1 - 20 Hz, but with even the heaviest weight the resonant frequency was in the KHz.
So to reduce the resonant frequency and get some useful signals, I took some washers slapped them on a bolt and some nuts and experimented. I used a Oscilloscope with FFT and changed the weight on the tip of the film until frequencies of around 40Hz were the largest. If you don't own an oscilloscope, just add a little weight and then hit the sensor. It should flop around for about half a second to a second before coming to rest.
Once you have the sensor tuned to the right frequency, place it in your breadboard at one end, you're going to need the space for the rest of the circuit.
As you can see from the picture, I taped down the base of the sensor. This is because the leads on the piezo film is flat, and tends to be loose inside the breadboard, so any vibrations tend to get lost in the movement of the leads.
Taping it so that the base can't move will ensure that your data is accurate!
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A 30-80Hz detector might sense trucks rumbling by or heavy footsteps, but not earthquake ground vibration unless it's from furniture falling over.
A great resource is http://psn.quake.net/ with many DIY seismometer designs.
Thanks for the resource though!
If you wanted to lower the resonant frequency of the sensor, it's as simple as adding more weight on the sensor.
If I didn't want to shorten the sketch nor by an Arduino Mega, could I use an external EEPROM?
There are also some efficiency improvements that can be made to save more space.
I was just not concerned with that since the MEGA has so much space on it
A good example:
I use a float to compare a previous measurement with the next measurement
A more efficient way would be to just use the A/D converter's integer value for both, and then convert it to voltage/float right before sending it to pachube.
The walkway to my front door is a wood deck of 2x4s and I've been trying to think of a way to illuninate it as people walk across it.
All you would have to do is remove some weight from the sensor and change the caps in the charge amp section to lower values to amplify higher frequencies