In this video I’m going to show you how to
make a speaker out of an old hard disk! First, get an old hard disk that you don’t
care about any more. Use a hex wrench to remove the screws.
Now you’ll be able to see the guts of the drive. You’ve got the hard platters where
the data is stored, hence the name “hard disk”. And you’ve got the heads which move around
to read the data. Connected to the head assembly you are going
to see this flexible cable and we’re going to remove the screws of the flex circuit that
it’s attached to. Flip this thing over and either tape it down
or glue it in place. Be careful to not break the flexible cable.
Next, get out your multimeter, set it to measure resistance, and look for a resistance of around
4 to 40 ohms between any two points on the connector. This means you’ve found the connection
to the hard drive’s voice coil. Solder some thin and flexible wire to those
connection points, and double check the resistance is still in the correct range. My coil is
around 12 ohms. Now if you connect those wires to a 5 volt
power source, you should see the heads jump! The next step is to connect your hard drive
speaker to an amplified audio source. The key word here is amplified. You don’t want
to hook this up to your phone or laptop’s headphone jack. Find an old amplifier that
is used to drive actual speakers, or you can browse my other videos if you want to learn
how to make your own. Slowly turn up the volume and…
So how does this work? Well you can tell your friends it’s magic but the real answer is
under here. If we unscrew this part, you can see that
we have a coil of wire attached to the drive’s head, and that’s right next to a strong magnet.
In other words we have a system very similar to a normal loudspeaker. Which raises the
question… how does a speaker work? Well, let’s say we have a magnet, and it has
a north and south pole. Then let’s say we have a coil of wire next
to it. And let’s attach something mechanical to it.
It could be a speaker cone or it could be a hard drive head.
If we pass an electric current through the coil, it creates a magnetic field around it.
The coil’s south pole gets attracted to the magnet’s north pole, and the speaker moves.
Now if we change the direction of the electric current, we change the direction of the magnetic
field. Now we have two north poles next to each other, and they are going to push each
other away, so the speaker moves in the other direction. If we do this with an amplified audio signal… Thanks for watching, and check out my other
videos about electronics!