There are many things we take for granted today and I’m constantly struck by how little curiosity exists in people born after the 2000’s. Obviously not You as you are reading this but even the most common things around us are somehow shrouded in mystery to most people.
One such ubiquitous item is the electric lighter, the ones that go “click”. That click is a small hammer hitting a piece of crystal that produces a spark. Today we use special PTZ material but could be made with quartz.
Quartz is one of the most common minerals in the world, second only to Feldspar, and is piezoelectric. I love piezoelectric materials. There is something inherently magic about a rock that can electro-shock you if you hit it hard enough.
Piezoelectricity is a fascinating phenomenon that occurs in certain materials, allowing them to convert mechanical stress into electrical energy, and vice versa. Here's a breakdown of how it works:
The piezoelectric Effect was discovered in the 19th century by Jacques and Pierre Curie, the piezoelectric effect occurs in specific crystalline materials, including quartz, Rochelle salt, and certain ceramics. These materials generate an electrical charge in response to applied mechanical stress.
What makes those materials interesting is that the piezoelectric effect is their ability to precisely convert between mechanical and electrical energy, which means it is reversible. So when an electric field is applied to piezoelectric materials, they change shape slightly.
This makes them essential in sensors like accelerometers, pressure sensors, and microphones to convert mechanical signals (like sound waves or vibrations) into electrical signals. Or actuators that create precise movements or vibrations in devices like inkjet printers, loudspeakers, and precise positioning systems by converting electrical signals into mechanical displacement.
Another, to me, highly interesting aspect that I will cover in future posts is Energy Harvesting. Piezoelectric materials can be used to generate electricity from mechanical movements, such as footfalls on a floor, making them useful for low-power energy harvesting applications.
Besides the electric lighter another ubiquitous application of quartz is in timekeeping. All modern digital watches have quartz crystal in them that is tuned to vibrate around 32.758 thousand vibrations a second (Hz).
Why 32.758kHz?
It is devisable by 2 so our modern binary systems can work with it. A simple binary counter or flip-flop counter counts those oscillations and to reduce a frequency from 32.758 kHz to 1 Hz using a binary counter we need a minimum of 15 flip-flops. This binary counter would count the number of input pulses and generate one output pulse for every 32,758 input pulses, effectively dividing the frequency by 32,758 to achieve the desired 1 Hz output or 1 second, and do that indefinitely without error. There is a slight error as no crystal is perfect but much, much better than mechanical clocks.
Most of today’s electronics have crystals in them. They provide a consistent signal rate on which all digital electronics rely to work.
Quartz is derived from the German word for hard, and as the name implies it is a 7 out of 10 on the Mohs scale of hardness. It is not as hard as titanium or diamonds, but it is harder than other natural and human-made materials.
It is a framework silicate, also known as a tectosilicate, meaning it has a three-dimensional network of silicon-oxygen tetrahedra. Each silicon atom is covalently bonded to four oxygen atoms, forming a tetrahedral unit. These tetrahedra are then linked together by sharing oxygen atoms, resulting in a continuous framework of SiO4 silicon–oxygen tetrahedra, with silicon atoms in a 4-coordination and oxygen in a 2-coordination. This robust three-dimensional network is responsible for quartz's high hardness and its lack of cleavage planes, which means it doesn't break along smooth, flat surfaces as some other minerals do.
So, that's a little background on Quartz. The real treat is the video below.
I love watching old educational videos, maybe I’m old fashioned but I find that they convey information much more fluently, and don’t insult my intelligence.