Piezo Vibration Sensor

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Brybro
 
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Joined: Thu Mar 06, 2014 11:10 pm

Piezo Vibration Sensor

Post by Brybro »

Hello! My name is Bryant and I am a senior in high school. I am trying to build a volleyball Sport Court tile that has sensors inside to detect whether a volleyball hit the ball and sense if it was in or out depending on which tile it hit. To do so, I bought Piezo vibration sensors as seen here:

http://www.karlssonrobotics.com/cart/pi ... MgodpUcALA

I have somewhat figured out how to program them to give me a "sensorReading", however, they don't always produce a value whenever I hit the sensor or flick it. It is very inconsistent and I don't know what I am doing wrong.

I have it wired to a bread board that is connected to an Arduino Uno board. I am using a 820k ohm resistor too. Whenever the resistor isn't plugged in, the sensor detects everything: even the noise in the air. But when the resistor is in, it barely detects any contact or vibration from the sensor. I have tried a 180k resistor along with a 1M resistor and it has the same results.

I can take a picture of the circuit if needed. But if anyone has an ideal or suggestion on what I may be doing wrong, please let me know!
I plan on putting one of these sensors under a volleyball Sport Court tile to detect the vibration as a ball hits the tile. The reason why I need to know the values that sensor detects is because I am also programming it to only turn on a light when a ball hits the till and not when someone steps or lands on the tile.

So please, any help would be great! Thanks!

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adafruit_support_mike
 
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Joined: Thu Feb 11, 2010 2:51 pm

Re: Piezo Vibration Sensor

Post by adafruit_support_mike »

We don't carry that sensor, so I'm afraid we don't know anything about working with it. The sensor's technical manual (http://www.karlssonrobotics.com/datashe ... echman.pdf) contains a lot of information.

I only skimmed through the manual, but I got the impression that these are tricky sensors to work with.. they seem to combine the properties of a flex sensor, a microphone, and a thermocouple. The circuit diagrams starting around page 38 make sense to me, but aren't the kind of thing I'd wish on a beginner.

All piezo sensors generate electricity when they're flexed, and the copy on the product page says this one can go up to 90v. You'd need to add circuitry to keep the sensor from killing the inputs of an Arduino or ADC.. especially since you want to catch impact events, which will generate short bursts of high voltage.

Honestly, I think you'd have better luck with a force-sensitive resistor (http://www.adafruit.com/products/1075) or an accelerometer. They cost a bit more, but they're easier to work with.

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