I pestered my lady all day long and she finally told me how she made this sound. She wrapped a wire around my external hard drive about 10 or 20 times and stuck it in the microphone-in hole. Then plugged in the usb cable. She just recorded the spin up and spin down into a wav file. She slowed down the recording with Audacity, some sort of sound editor, about 80% slower, and put a slight echo with fft.
:facepalm
retty cool, I'm surprised I didn't pick-up on this, because, you can clearly hear the stiction test, where the platter is briefly pulsed to test the bearing integrity and see if the platters spin. This is not stiction in the heads, as they rest on a slider when the platters aren't spinning. Bearing stiction.. then full power is applied and the drive spins up! Then spins down.
0:01 power applied.
0:02 is the initial platter rotate. And just before that are the clicks of the power mosfets sending genuine electrons to the motor.
0:04 is the full-power spinup.
0:07 platters are running full speed
0:08 - 0:24 some data transfer and head movements.
0:24 - 0:29 is spindown, the noise spike at 0:235 is the heads being retracted in a power-loss situation. The spinning platter acts as a generator which provides a few moments of power to pull the heads back and lock them against a magnetic catch. There is no spring retraction.
The drive either has enough power from the usb port, or kinetic rotational flywheel energy uhm, yeh, that stuff to pull the heads back onto the load/unload ramp.
All the static you hear is the electronic noise and data transfer and head movements. And there is a lot of it I'm sure.
Here is the unmodded recording, you can do this same experiment with just a length of wire.
View attachment 6533
