Very basic vibration sensor question

Hi,

I have project where I have to detect vibration (about as much vibration as you'd feel if you had your hand on the hood of a running car). I thought I'd be able to use a simple piezo element (https://www.sparkfun.com/products/10293?) but unless I'm doing something wrong it doesn't seem sensitive enough.

Is there another simple sensor that would do a better job of detecting subtle vibration?

Thanks!

An accelerometer can be used for sensing vibration.

A multiple axis accelerometer will work better than a single axis. Then you won't have to guess which axis is better for sensing the vibration.

Since you are trying to sense very low vibration I would try a low g accelerometer, somewhere under 3g. Sparkfun offers a digital ADXL345? that is 1.5g & 6g selectable, 3 axis accelerometer. They have a few different types to choose from. Adafruit offers an analog 3g & 16g, 3 axis accelerometer.

Good luck :)

Thank you so much for your reply! I just ordered the ADXL345. Hopefully it will be sensitive enough to detect the amount of vibration I have to work with.

All the very best, LT

the hood of a running car

That may be too fast for an accelerometer. Try a piezo instead. If it is not sensitive enough, you can always amplify it.

dhenry,

Thank you for your reply. As I stated in my original post I am using a piezo at this point. This is what I have right now (http://garagelab.com/profiles/blogs/tutorial-piezo-element-as-a-sensor-with-arduino but, as I've stated, the only way I get any data out of the piezo is when I tap on it directly.

How would I "amplify" it to the point where it would be able to detect the subtle vibration?

Thanks in advance! LT

The piezo you are using is originally intended as a sound output device. It can be used as a crude "knock" sensor but as to a quality or sensitive vibration sensor ???? The main problem with building a vibration detector is that the sensor requires movement of part of the piezo relative to other parts of it. (Relative motion equals signal) You could try glueing a piece of rod (thick nail) central and vertical to the element and , holding the element via its edge, applying the rod to the bonnet might permit you to pick up a signal.