# Sensor for vibration and impulse

hello guys,

i m here to ask you to help me in my project of sensor for vibration
i tryed to use some small piezo disk but it's very unstable and not very useful

i will try to explain what is in my mind

for my work i have a device that makes electromagnetic impulse like a scalpel, and i would like to use arduino to undestand the frequency of vibration of each shoot that will let me undrestand the constincency of the material i m going to hit

could you advice me the kind of sensor or system i could use for my propose?

thank you veery much!!!

I don't understand your plan to use an electromagnetic impulse "like a scalpel" . You mean, like a very small arc-welder ?

I m sorry for my english but I meant a chisel that work under power of magnetic coil.
So everytime the coil gives a shot the chisel hit the surface.
I would like to caputure the frequency of each hit for different surfaces

An accelerometer.

A microphone? Depends a lot on what range of frequencies you want to measure

attached you will see my device and maybe you can advice how i can connect the sensor

You said that you want to "caputure the frequency of each hit for different surfaces" - do you want the frequency at which that device drives the chisel (is than not just in the specification for the device?) or do you want something else? I'm guessing that is a medical device, what does it do?

That s right Sirch,
It s a medical device and very simple one.
In the hand piece there is a solenod that give shot to te chisel and i can chose quantity of strongness for each shot
Now i would like to use arduino to know what kind of material i hitting using a sensor

Assuming the device operates in the 10 to 1000 strokes per second range I consider using a microphone and amplifier connected to one of the analog pins of the Arduino. You would need to sample the sound and then work out the frequency, a Fast Fourier Transform may be the way to go Arduinoos » Blog Archive » Fast Fourier Transform (FFT) (Part 1)

Great!!! I think will be perfect this option i will try to find all necessary components to make sone tests.
By the way this device works making 1 stroke every 1 up to 10 seconds

Sorry but how can i connect the amplifier to the arduino analog input?

This is where it becomes a bit more technical than just plugging one thing into another...

If you have a typical, simple audio amp circuit, then essentially it's a case of replacing the speaker with with the arduino - BUT the Arduino analog pin needs 0-5v so you need to get the amp output into this range, this could be as simple as adjusting the volume appropriately but you may need to bias the output so that the audio signal oscillates around 2.5V to give you a swing between 0 and 5V.

One thought that comes to mind as an initial test is to plug the microphone/amp output into a computer sound card - there are some "sound card oscilloscope" programs out there- look on google.