I have always been fascinated by the precision mechanics present in mechanical hard drives and every time I have a broken one I try to find a use for it.
This, together with the fact that I think it's a shame to throw away such a precious piece of technology, made me think of this project.
The main idea of the project is to use the mechanics related to the movement of the magnetic head of an old hard disk to create a display showing the current time (it can be easily changed to display whatever you want).
By replacing the Hard disk magnetic head with a bar of leds and by turning on the leds at the right time it is possible, using the persistence of the human eye, to form an image. For the led bar I used one equipped with the well known LED WS2812B that gives the possibility to control the leds with only one pin (besides the power supply of course).
I have upgraded the spring to magnets. Much better. The instructable is now updated as well.