Seismometer Arduino
Gene Cryder
First of all, I am very new to Arduino. I have tried some really basic examples and tutorials, but I need to get a more complex project working. I chose this one:
-mpu6050-seismometer-with-data-logger-9e6bf5
I got all the parts and have built the circuit on a breadboard. I couldn't find any regular Nano boards where I live, so I got a couple of Nano Everys instead. I also couldn't find the same exact accelerometer from the example, so I got a GY-521 instead. The person from the electronics shop assured me they would work just as well as the components in the example (I hope this was true!).
EDITED TO SHOW CURRENT ISSUE:
I managed to verify/compile all the codes from the project, but can't get them to work yet. Since I am very new to Arduino and this is my first test of the Nano Every, I decided
to try and get a super simple example, like the Blink code, working, to see if everything was ok with the board. And it seems it's not! I am using the Arduino IDE on Win10, and this is the code I am trying to upload to the board:
My bad. Somehow I assumed that was the same Filters library you can find in the library manager, but it seems it's not. I uploaded this one instead and that seems to solve the 'FilterOnePole' problem (yay!).
Editing the post to show my current problem with the project. Thank you johnwasser!
A couple of years ago I built the TC1 seismometer, which works very well, but it is technically difficult for young students to make the detector, especially winding the coil. Most schools that undertake the TC1 project buy the kit, which is pretty expensive.
I should have explained further. I have a Guralp 40t seismometer but need an analog-to-digital digitizer. I am not referring to just an ADC, but analog signal input (three chanels); some amplification; digital conversion (ADC); and final output to USB.
Per the Guralp 40T spec sheet, it has something on the order of 150 dB dynamic range which implies a 26 bit (or better) ADC. An ADC that doesn't significantly limit sensor performance is going to be a standalone ADC, not integrated on a microcontroller.
This seismometer detects ground motion with a magnet hanging on a slinky. The magnet is free to bounce up and down. A stationary coil of wire is placed around the magnet. Any motion of the magnet generates tiny currents in the wire, which can be measured.
The first thing we did was make our coil of wire. In our first model, we used PVC end caps pressed on either end of a short section of pipe to form walls on either side of the wrapped wire. We sliced the ends off to open it back up. We cut a section of 1" PVC Pipe and wrapped about 2,500 turns using 42 gauge magnet wire.
The pipe is a great way to make it from inexpensive, readily available parts. We used PVC end caps pressed on either end of a short section of pipe to form walls on either side of the wrapped wire. We sliced the ends off to open it back up.
We made a fancier version of a wire spool using some 3D printed parts. This was much easier to wrap, because it attached to the spool-winding feature of an old sewing machine. In the short video, you can see how we wound it. If you have access to a 3D Printer and want to use our models, let us know and we can send you the files! Also note the bigger wires in the photos. We soldered the end of the magnet wire to the thicker wire, which is then easier to work with.
We used a Slinky Jr which has a smaller diameter than a full-size slinky. At the bottom, we mounted two RC44 ring magnets stacked together on a 6" long piece of #4-40 threaded rod. These magnets sit inside of the wire, and when they move, they induce a current in the wire.
At the top of the slinky, we mounted another magnet onto a steel plate for the slinky to hook onto. In the video, we show how to calibrate your slinky to be 1 Hz. This is a crucial step to getting the frequency right. The slinky should bounce up and down once, in one second.
There is also an R848 ring magnet at the bottom of the threaded rod. This magnet sits inside of a little section of copper pipe. This helps dampen the motion, to reduce noise, and to see that the slinky will only bounce when there is adequate shaking!
The magnet moving inside of the coil of wire produces very small currents, so we need to amplify them so we can see the tiny signal. There are a lot of good amplifier circuits out there, we stuck to the circuit used in the TC1 seismometer we found online. In the picture, you can see the schematic for the amp circuit. We simply used a breadboard!
The Arduino board takes in the analog signal from the amplifier and translates that into a stream of digital, numerical data. To do this, the Arduino was programmed with code from the TC1 Seismometer project that was mentioned in the beginning of this Instructable. Here is a link to that project again, which can help you setup your Arduino!
The Arduino plugs into a PC via USB. You'll need to load the Arduino software and drivers onto your PC. That software is what you'll use to get the code from your PC onto the Arduino board, using the "Upload" feature. You can see a quick video of the Arduino outputting data in the previous step.
Use the Arduino software to make sure the board is communicating properly. Click "Tools>Serial Monitor". If everything is running properly, you should see a stream of numbers coming in. If not, try making sure it's looking at the right COM port. Again, the video is in the previous step!
To record the data, we used an application on PC called jAmaSeis, from IRIS, the Incorporated Research Institutions for Seismology. In the old days, seismometers would output to a paper chart recorder. A pen would move back and forth on top of a slowly spinning roll of paper. The jAmaSeis uses the same format, but puts it on a computer screen.
We recorded several earthquakes from around the world with our seismometer! But sometimes, the quakes can get lost in the noise of the system. The system is extremely sensitive! The heat from the sun causing the concrete to expand slightly got picked up by our seismometer. Also, a nearby heater in the building caused noise too! There are many things that could cause noise.
In the screenshot above, you can see what noise looks like, but when a seismic event happens, it looks much different and is quite distinguishable from the noise. We blocked the sunlight from coming in, which did help reduce the noise a little bit. Even though there is noise, we were still able to see many earthquakes and even a volcano eruption!
It is a very interesting subject to study, but in short, there are certain parts of the world that we will not see earthquakes from. Here in Eastern Pennsylvania, we can't see Earthquakes in the red area. We will only be able to detect P-Waves, (not S-waves) in the yellow area.
We were able to build a complete seismometer for under $100. One of the important ideas behind this simple design is to make it inexpensive and accessible. Many of the folks who ask us about this want to build one for their science classroom.
-Electronic parts: For the amplifier circuit, we purchased electrical components from Digikey. The quantities below are what you need to build one seismometer. We ordered a few extra of everything, though, in case we messed anything up during the build.
Ted Channel, the creator of the TC1 Seismometer, recently reached out to us to share his invention: an open source seismometer kit that users can build to measure ground activity. I wanted to share his designs, as this would be a fantastic kit for classes from junior high school through university.
Can you briefly describe how your seismometer works?
The TC1 is a simple Slinky toy spring and coil, through which a very strong magnet passes, creating a current during an earthquake. The voltage is amplified and displayed on a computer, using free software. It is very simple but very capable. It can record local earthquakes at 2, 3 and 4M, and teleseismic earthquakes greater than 7M from around the world.
What could a group of students learn by making one and collecting data?
The TC1 is a great educational tool and an interesting adventure. Students and teachers will see, firsthand, Earth sciences in action. Electronics, Seismology, Geology, Magnetism, Geography, Physics and current events are just a few of the components users are exposed to.
Where can teachers and students get the components? You offer a kit, right?
I only sell the unit as a complete package: the sensor; the interface, which uses an Arduino Uno; and cables. All you add is the curiosity and a computer with the loaded software. Contact me directly through my site.
If you tried to find this device in a search, "geophone" will get a lot of info. I didn't see the period mentioned.One thing. The piece of copper tubing for a damper is on the same axis as the sense coil and I wonder about the back EMF for the current in the tube (very high current) is coupling to the sense coil? Dampers of this sort are usually a flat plate. The alternative is a resistance across the sense coil and no other damping.
Or, and this gets to be a block box approach for most people, no extra damping, measure the mechanical damping and period of the system, solve the 2nd order DEQ for ground motion, and numerically integrate continuously. This actually gets you the most useful data and with the least number of parts.
In my Earthquakes and Society course I use an arduino and MEMs sensor to introduce students to seismograms and to help them develop an intuitive understanding of seismogram analysis. The idea is to have them build their own sensors and explore the motions they can produce with the simple system (while it is connected to the computer in the classroom). The picture is pretty much all the information they need to connect the hardware, but I provide a little background on a breadboard, etc. Within a few minutes, non-science students are quite comfortable with the system.
c80f0f1006