Hi Everyone,
Any ideas on an Arduino based seismograph ... seismometer ... Has anyone seen this idea roughed out?
Anyone have any ideas on what is required to build an arduino based seismograph? Am I posting in the wrong forum again?
What hardware do you plan on using for monitoring for vibration? Use to be surplus geophones about for reasonable prices.
I have a couple arduinos, one broken mega and a broken UBW32. I was thinking something fasionable, fits in my purse and isn't based on an iphone... networking could be an interesting idea.
I saw an interesting idea in a Forrest Mims book from Radio Shack. He took a magnet and suspended on a string above a coil. If the magnet was disturbed (by shaking), it would swing back and forth. This would create a voltage and current in the coil. The strength of the voltage and current would be dependent on the amount of swing. He had suggested installing this in a tube so that air currents wouldn't disturb it. He also suggested mounting it on a concrete pad, such as in a garage.
Yes there are two problems with that setup. First of all it is easy to disturb with drafts and knocks or local things like slamming the garage door.
Second is it needs a big coil, an article I saw talked about taking a drum of 40SWG wire and getting the end out and using that as a coil. They said at least 2000 turns was necessary.
Also the pendlum arm of a seismograph needs to be mechanically, magnetically or electrically dampened to respond correctly to the frequencies of earthquakes Vs higher speed vibrations. There are a lot of designs out on the web if you goggle around. Interfacing surplus geophones is a simple way to get started. There is usually analog amplification and filtering required before you should wire to an Arduino analog input pin.
Lefty
One issue will be dynamic range - seismic waves vary in amplitude by large factors if you have a sensitive seisomograph, and the 10bit ADC of the arduino is a bit limited. You might want to consider sending several outputs of differing amplification to ADC inputs so that you can get both high amplitude and low amplitude sampling - that way you control quantization error and have headroom for large signals.
Forgive me for straying from matters Arduino, but there is a discussion of building a seismograph at....
http://psn.quake.net/lehmntxt.html
... which may repay study. Why cite that one, when there are so many others to choose from? Especially as it is dated?
It comes from the once well known Scientific American "Amateur Scientist" column. For many, many years this excellent magazine produced well researched projects.
The electonics side in the article is out of date, but everything else, including the spec for the sensor, is still good. Just a little work on the output of the coil should be all you need.
Oh.. and of course today we don't need a chart recorder to capture the data, do we!
Would an accelerometer be sensitive enough to detect a small earthquake? A 3-axis accelerometer could even detect the direction of the epicenter.
Good luck getting an accurate reading in your purse tho.