Arduino Prototyping Inputs #49: Knock Sensor

Piezo sensors have a lot of different uses, but one of the more unique uses is called a knock sensor. By leveraging the fact that piezo generate electricity when they move, you can hook them up and identify when a vibration is felt. Unlike a vibration sensor, you can adjust its sensitivity through code.👉 Leave a tip via cryptocurrency if I've helped you out:

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A few other FREE sensor tutorials you might like: (I have 100's!)
A few other sensor tutorials you might like: (I have 100's!)

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[rongarza]

My electronic drum kit's pads have the same type of piezo in an airtight cylinder. When the pad is hit, the pressure inside the cylinder increases and triggers the piezo, the "brains" then plays the sound associated with that sensor.

[davidbean]

To increase sensitivity you can add a small neodymium to each side of the piezoelectric element. I have found it greatly improved the sensitivity.

[mohgujai]

Why do you need resistor across Ground and A0? I thought the Piezo just generates a voltage (no more than 5v) and then the aruidno should just read it?

[uidrum]

Thank you for the video! Quick question: Sorry I'm new to electronics... what is the wattage and tolerance of the 1M resistor?

[downeastlife]

Can anyone help me create something that detects hits but have it be about .5 inches and wireless and connect it to a phone app with flutter

[punkin]

Hi Marc, I followed your wiring and code, but I'm having trouble with the sensitivity. As I change the sensitivity it seems to go from not being able to sense, to being oversensitive and repeating "knock!" without interruption (no new input on the sensor). What could be going on?

[aarontaylor]

Hi great video btw I have a question is there a way to program the Piezo with the Arduino to make direct contact with the Piezo not just vibration?

[mindstormsnxtbuilder]

Can i measure the amplitude using this element? Lets say im placing multiple piezo elements on a surface and hitting a certian point. Is there a way to tell which element gave the input with the highest amplitude?

[okekejeff]

Would there be any change when you add the piezoelectric vibration module to the sensor?

[jeffbowyer]

In Arduino's IDE, "Examples 02. Digital toneKeyboard" requires 3x force sensing resistors. Can I use one of those force sensing resistors for this Knock Sensor project? If not, why not? Thanks for your guidance.

[ryanchan]

Does the piezos analogue output vary by how hard you knock it? Like would a harder knock cause a stronger electric pulse?

[fazrulislam]

Can this sensor measure the vibration of machine? Like textile weaving, knitting machine..

[pedrohenriqueborges]

can i put it behind a door and receive its vibration? and why connect the resistor in parallel with the piezo?

[selinacervantes]

Would someone be able to explain to me how the sensitivity works? I think I understand but I am not 100% sure? I understand that the lower the number on the code, the higher the sensitivity. From what I can understand from the code: when I hit the piezo it generates a voltage. The arduino detects that voltage. The sensitivity changes ONLY the response of the arduino?

For example, if it is closer to 0, then the arduino will displace “knock” at a lower piezo voltage (assuming 0.1) compared to being set to 300 which requires the arduino to respond to a much higher voltage (assuming 5)?

So the sensitivity does nothing to the piezo itself, just the reaction of the arduino to the amount of voltage released by the piezo?

[pavansachi]

Great informative video. Hope you can help me. I have a sensitivity of 15 and tried upto 20. But output from piezo is very inconsistent. It registers a value above 20 after 3 to 4 clicks. So I can't get the toggle behavior. What's wrong?

[Masiyamusic]

can the arduino be set to switch the led off after a set time

[Sick]

Nobody explains the 1M resistor and it's function in the circuit .. like what does it do .. why 1M .. what if we take another value ...

[omarkhalaf]

Can this knock sensor detect vibrations in the air or does it only detect sound waves through solid material?

[RicoNNectnd]

Never get 0 out of it. Its always abput 70. after one knock, it holds about 200 for a certain time and slowly reduce itself back to 70

[richachauhan]

can you please tell that If I want to connect more then 1 piezoelectric sensor to Arduino ..then How can I do it??