Quartz crystals are made of silicon dioxide like most sand. The
mineral is found in a huge variety of rocks in the crust of the earth.
What makes quartz interesting is that the crystals have three very
Quartz is durable unaffected by most solvents and remains
crystalline to hundreds of degrees celsius.
The property that makes it an electronic miracle is the fact that,
when compressed or bent, it generates a charge or voltage on its
surface. This is a fairly common phenomenon called the Piezoelectric
effect. In the same way, if a voltage is applied, quartz will
bend or change its shape very slightly. If a bell were shaped by
grinding a single crystal of quartz, it would ring for minutes after
When any quartz crystal vibrates it always does so at exactly
32768 times each second.
So quartz crystals can be used to make Radios and to make very accurate
Radio stations send their content out by generating electromagnetic waves.
A small amount of energy from the radio wave is captured by the antenna
wire and is taken to the coil. The coil has to be designed just right to
capture only the frequency we are trying to receive. So for example the Am
frequency 610 kHz.
The height peaks and troughs from an AM radio station sends the
sounds through the air
By winding just the right amount of wire on just the right diameter coil
form, the coil will be what we call "resonant" and "ring". In other words
it will be able to store the energy of the radio wave we want to hear. All
other radio waves not "resonant" will pass through the coil and out the
other side to the ground.
A small amount of the radio wave energy stored in the coil (our 610 kHz or
610,000 cycles per second) moves to the detector or the device called a
diode, in this case a quartz crystal is used. The energy is an alternating
current signal (AC) at this point. The quartz crystal detector (diode)
rejects half of the alternating current signal and the signal looks like
image below. Now the signal is a pulsating direct current (DC) signal that
can be heard as sound in the earphones.
If both sides of the wave were used, they would cancel each other out as
they are opposite of each other. As this energy goes into the earphone,
the amplitude or strength of the signal varies because the wave is
"modulated". This energy is converted by mechanical means in the internal
workings of the earphone. The sound waves exit the earphone which you
perceive as the original sounds from the radio station.
You can tune the coil to get different frequencies. That can be done by
adding more turns of wire around the coil form. Or removing some. On a
simple radio, this is done by sliding the wire from the quartz crystal
along the length of the coil making the coil longer or shorter. , until
the desired radio station is found..
The lead mineral crystal galena can also be used as a detector / diode.
Diodes, in this case crystals only permit a signal to move in one
direction so the peaks and troughs of the radio wave are converted to just
Watches Quartz watches work because the crystal itself is
piezoelectric, which means it vibrates when you apply an electrical
current to it.
All quartz crystals, if shaped in the right direction to the crystalline
axis, vibrate at a very at exactly 32,768 times per second.
The best quartz crystal shapes are a straight bar or a disk. A bar has the
advantage of keeping the same frequency provided the ratio of length to
width remains the same. If the surface voltage on the crystal is picked
off with plated electrodes and amplified by a transistor or integrated
circuit, it can be re-applied to keep the crystal vibrating.
Do quartz crystals have magical healing properties?
They have interesting properties but no medical studies directly indicate