Adabot finds treasure in his rock collection – Quartz! Have a look inside a quartz watch and learn why quartz is so important for electronics.
Adabot: Sandstone, obsidian, pyrite …
Minerva: Hey Adabot - what you up to?
Adabot: Oh - I was just going through my rock collection. I forgot I had so many!
Minerva: Hmm - find anything good?
Adabot: Sure - some precious stones. This one’s my favorite - it’s quartz!
Minerva: That quartz does look special. Where did you get it?
Adabot: There was a rock show at the museum. I thought there would be more guitar solos, but it turned out to be a bunch of people trading minerals. So, I got this quartz because it looks really neat.
Minerva: It looks neat because it is neat. We use quartz in electronics all the time.
Hans: Did someone say time?!
Minerva: Why, yes! I was just explaining to Adabot how quartz is used in electronics.
Hans: Adabot - do yo know why I am the world’s greatest integrated circuit?
Adabot: No, Hans - why are you the world’s greatest int –
Hans: Timing! It’s what I take care of in a circuit. And do you know why my timing is so impeccable?
Adabot: No - why is your timing so imp–
Hans: Quartz! And why does quartz create perfect timing?
Adabot: Umm - are you gonna keep interrupting me?
Minerva: Oh - settle down, Hans. I can explain why quartz is so important for timing.
Adabot: Why, thank you.
Minerva: You see - certain materials, such as quartz crystals, are Piezoelectric. Simply put - this means if you apply a small amount of mechanical force to a piece of quartz, it will generate a small electrical voltage.
Adabot: Wow - that sounds pretty unusual! So if i crushed it, it would shock me?
Minerva: Well, you have to squeeze it very lightly, and just right and the electrical voltage is very, very small. But...yes I suppose you’re right!
Hans: And the opposite is also true! If you apply voltage to a piece of quartz - it will respond with a precise mechanical vibration.
Adabot: Quartz sounds like magic!
Minerva: It’s not magic, Adabot - it’s science! Take a look inside this quartz watch for instance.
Hans: this little integrated circuit here passes electrical current to the quartz crystal. Then the quartz vibrates at precisely 32768 times per second.
Minerva: After that, the IC detects the vibrations, counts them one by one, and when it gets all 32,768 it knows one second has passed!
Adabot: So there’s a quartz crystal inside of that little metal container?
Hans: Yes - and it looks something like this …
Adabot: That looks like a tuning fork!
Minerva: That’s true - it does look like a tuning fork!
Adabot: Musicians use the vibrations of a tuning fork to tune their instrument - and circuits use quartz to tune their timing!
Hans: You’re right!
Minerva: Very true, Adabot. Quartz is an important reference for the timing of so many circuits - microcontrollers, computers, and more.
Adabot: I always wondered what was inside those little metal cans - now I finally know!
Minerva: Well - it’s about time!
Hans: … Adabot, I believe Minerva just made a *time* joke
Adabot: Is that what that was?
Minerva: Thank you, thank you …
To understand why quartz is so useful for electronics, we need to understand piezoelectricity. Wikipedia defines piezoelectricity as such:
image: CC BY-SA Tizeff
Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure and latent heat. It is derived from the Greek word piezein, which means to squeeze or press, and ēlektron, which means amber, an ancient source of electric charge. French physicists Jacques and Pierre Curie discovered piezoelectricity in 1880.
The piezoelectric effect results from the linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry. The piezoelectric effect is a reversible process: materials exhibiting the piezoelectric effect (the internal generation of electrical charge resulting from an applied mechanical force) also exhibit the reverse piezoelectric effect, the internal generation of a mechanical strain resulting from an applied electrical field.
In electronics, the piezoelectric properties of quartz are used in the form of a crystal oscillator to provide a stable and reliable timing reference. Quartz's reference frequency is used like a drumbeat for digital processors to follow along with. It keeps software instructions moving along at a consistent rhythm!
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency. This frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.
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This guide was first published on Mar 19, 2019. It was last updated on Mar 19, 2019.