so what's a voice coil is that one of those uh twisty cables on an older style
telephone that you always seem to hit stuff with as you moved around the
room no while voice coils are indeed
coils of wire the term is typically used
to refer to one of two things the wires
that actuate the ARM of a hard drive or
the wires that make your speakers go bum
you know both of those applications benefit from the main strengths of voice
coils extreme accuracy and high movement
speed you see voice coils move by using
something called the Lorent Force which is created by placing a coil of wire in
a fixed magnetic field when current is
put through the coil it turns into an electromagnet making it either be
repelled or attracted to the fixed magnetic field giving you a force this
force can actually be quite strong
meaning that voice coils can speed up or
slow down extremely quickly speakers for
example can accelerate at rates in the ballpark of 800 m/s squared or 80
G's put into context that is 16 times
the ex acceleration required to make you lose Consciousness 27 times quicker than
a space shuttle launch and 21 times faster than my
Lamborghini but how exactly does that make your speakers and your microphones
work well for a microphone as we've
covered in more depth here there's a membrane that moves back and forth as
sound waves hit it these vibrations are turned turned into an electrical signal
as a coil of wire on the back of the diaphragm moves over a magnet to turn
this electrical signal back into sound the process is reversed so the
electrical signal goes into the coil which moves the speaker to create your
sweet sweet beads and it's the extraordinary
acceleration and precision that we mentioned before that makes it possible
for speakers to produce such a wide variety of sounds on demand what about
computer hard drives then well you can learn more about them in an upcoming
video because we realized we haven't actually done one yet but in a nutshell
on one side of the ARM that hovers over
the spinning disc like a record needle is the head which is responsible for
reading or writing data on the platter
and then on the other side is a voice coil this this coil of wire is
surrounded by a permanent magnet that yada yada okay giving you everything
that you need to get your Loren force on
so to move the ARM current flows through the coil creating a force that causes it
to Pivot then just before the ARM of the
hard drive reaches its desired location the current's Reversed bringing it to a
stop exactly exactly where it needs to
be in fact thanks to this Lightning Fast
deceleration the arms of hard drives are able to be positioned within a millionth
of an inch or one for thousandth of a
human hair wow I got like five so now
you might be thinking why not just use voice coils for everything that needs to
move why don't we replace the Pistons in a car or use one to throw a ball for the
dog well here come the
downsides excessive magnetic for force and excessive heat are kind of problems
if you make a magnet too large it can be
difficult to tame the magnetic field it generates I mean a massive voice coil
wouldn't be that great if it ripped all the fillings out of your teeth or more
realistically like not in a cartoon wiped the data off of everything in a
10t radius also anything that has a
bunch of current going through a wire will tend to be a bit uh
toasty if you've ever had your speakers emit the magic black smoke that's most
likely why but this also doesn't mean that the applications of voice coils are
limited to our two examples from before
one of my favorite uses for them that you'll hopefully see more of in coming
years are voice coil actuated camera
stabilizers these are similar to gimal
image stabilizers but instead of using several rotating Motors they use you
guessed it voice coils to position the camera you got it again extreme speed
and accuracy this thing huh wow uses
badass voice coils and is so fast and so
precise that it can create two 30fps
videos from a single 60fps camera
repositioning the camera between each frame to give the illusion that there
are actually two separate cameras pretty
cool so to say that I'm amped to see where we're headed as they continue to
develop voice coil technology would be an understatement though I can't say
that I have my hopes up about a new speaker that will make Nickelback sound
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