Hello Friends!
Did you know that a piezo buzzer can be used to produce a tone when the voltage to it is turned on and off hundreds of times a second? Different frequencies produce different tones. As someone who is pretty much tone deaf I can’t quite confirm that the notes the buzzer produces are the right notes, but I did spend quite awhile trying to get it to play Fur Elise and it definitely sounds like something.
The circuit for my piezo buzzer using the arduino was probably one of the simplest so far. Three wires and the buzzer were all that were needed since the buzzer only has one positive and one negative pin. As the user, all that you need to do is to specify the frequencies, length of notes, and pauses to create a song.
So what does it mean that the buzzer is a piezo buzzer? It means that the buzzer is an electromechanical component, a device that uses an electrical signal to create mechanical movement. Piezoelectric devices create sound or vibration from an electrical signal or can create electrical signals from vibration or sound. Piezoelectric materials deform slightly when exposed to voltage across the structure or produce voltage when mechanically deformed. In the case of this buzzer, a coil of wire becomes magnetized by an applied current that causes it to pull towards a small magnet that is also in the buzzer. This causes a click which, as mentioned, creates tone if repeated hundreds of times a second.
I had never really thought about what piezoelectricity was. It turns out it is quite nifty. If you ever wondered how record players produced sound that you can hear from your speakers, wonder no more. Piezoelectricity is used to ‘read’ the sounds inscribed on the vinyl records. The word piezoelectricity means ‘electricity resulting from pressure’. Materials that are piezoelectric have crystal structures which repeat regularly but are not uniform. When in its static form, when no electricity is applied, the positives and negatives cancel each other out. When electricity is applied, or the material is pressed on, the structures are deformed; the non symmetrical nature of the repeating patterns causes net negative and net positive charges to form on opposite faces of the material.
Piezoelectric devices can be highly accurate compared to other possible methods of doing the same thing. Quartz used in a clock or watch can convert electrical energy into predictable oscillations to run a motor that in turn rotates the gears to turn the hands on the clock. In a record player, a needle tipped with diamond bumps up and down on the grooves causing vibrations, applying different pressures to a piezoelectric crystal which outputs electrical signals. Those signals are converted back to the noise that you hear.
Only specific materials are piezoelectric. Quartz, sucrose and Topaz are some which occur naturally. Learning more about these materials and learning to synthesize them to improve their piezoelectric properties is a focus of research both academically and in industry. Piezoelectric properties are also seen within the body, in tendons, enamel, and DNA to name a few.
So in the end, the simple act of making a buzzer play a tune has led me down an interesting path of discovery. I still feel like the things I don’t know are overwhelming in comparison to what I am learning but hey, anything is better than nothing. At least I have started to try and learn.
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