Every video I see on some introduction to time-keeping history says things changed when quartz was discovered. I remember commercials for watches actually bragging in marketing campaigns about quartz time-keeping or whatever it is called. I don’t know what about quartz (is it an element) made it so important for keeping accurate time.
Also, I wasn’t sure what flair to put this under. I can add another if someone has a better suggestion.
In: 89
You’re getting a lot of “quartz crystals vibrate at very precise frequencies.” While true, this isn’t the most important thing. A tuning fork vibrates at a very precise frequency. It’s how piano tuners do their job. You can count the vibrations that occur, and then say “this much time has passed.” Notice I did not say “count how many vibrations happen in a certain amount of time.” I said “count the vibrations and say this much time has passed.” You use the fork as a standard. Why don’t we just use a steel fork and call it good?
Well, the tone made by the fork rapidly dies off, so you have to hit it again. In addition, you need some way to count the vibrations. Electric circuits allow you to do this, and you can come up with a system where a tiny, electrically driven hammer hits the fork and you use some electric property to count the vibrations. Maybe make the fork magnetic and put the tines near a coil. This will let you get a signal similar to the way we generate a lot of our electric power. The issue is, this is going to be a large piece of equipment. Timex would like something you can carry in your pocket or wear on your wrist. They also want it to be cheap. Enter quartz.
Quartz is a type of rock (really a mineral that is basically sand) that has an interesting property. If you squeeze it, like in a clamp, it makes a small electrical voltage difference across its length and can push a very tiny electric current. This is how the push button igniters on gas grills work. The ‘ka-chunk’ sound is a mechanism that squeezes a piece of quartz with a very large pressure to make a spark, then releases that pressure. What’s useful about this property, though, is it runs the other way. If you apply a voltage difference across the quartz’s length, you can make it shrink a little bit, just as if you squeezed it.
[Make your tuning fork out of quartz](https://en.wikipedia.org/wiki/Tuning_fork#In_clocks_and_watches) (Wikipedia link). Instead of using a hammer, “hit” it with an electrical signal. This will cause it to vibrate, generating an electrical signal at the frequency of the fork. Clever circuit design will let you use this signal to drive the hammer so you hit the fork at the right time to make its vibration bigger, giving you a stronger signal to measure. The feedback creates a self-resonant circuit. Self-resonant circuits come in many varieties. (This is electro-mechanical, but things like a Colpitts or Hartely oscillator or tunnel diode oscillator are entirely electrical and can be built with very few components.)
Quartz is a stable material, meaning it doesn’t react with many things under typical conditions. You don’t have to worry about it rusting which would change the way it vibrates. Making the fork small limits issues that may arise if you tip it one way or the other due to the weight of the tines causing them to bend. If you want a very accurate signal you do need to worry about temperature differences. Since things expand and contract with temperature changes, the vibration of the quartz fork varies with temperature. High quality frequency counters have an oven option that maintains the quartz standard at a fixed temperature to provide improved stability.
Does this help clarify things?
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