When a hard drive reaches the end of its life, it usually does so catastrophically, sowing pain and despair in the heart of its owner. However, a damaged hard drive can find another life through DIY. Ben from the channel Ben Makes Everything shared a great example by turning an old hard drive into a laser projector, applying a good dose of Arduino and a considerable amount of trial and error.
I have many damaged hard drives. Too many. Detection errors, SMART warnings, and noises worthy of a Lovecraftian tale define these computer corpses. Obviously, nothing prevents me from experimenting with them to try to extract a little more life... but also there is the DIY route. What can we do with a damaged hard drive? Ben Makes Everything has a proposal: Build a laser projector. The idea is that the device has enough resolution to write text on the wall...
Building a Laser Projector from a Hard Drive
The hard drive essentially takes on the role of a system of rotation for a series of mirrors installed at different angles. When the laser hits them, the speed of the hard drive makes its light produce horizontal lines with a solid appearance on the wall (persistence of vision helps a lot here). The change in mirror angles projects the next line a little lower, and by turning the laser on and off, segments form that give rise to letters and text.
Obviously, it's easier said than done. The entire system must be perfectly synchronized, and that's when Ben started encountering tolerance errors, latency issues, and faulty components. Even the hard drive's PCB proved useless, and he had to control the motor with an external module. Add to that precision details in his 3D print for the mirror mount, lack of power in the laser, and some burnt-out diodes.
Despite these difficulties, the project was a success. Besides reproducing text with acceptable quality (a line of 20 characters at 27 meters distance), Ben achieved the portability he so wanted for his system. Since it's a prototype, it's not hard to imagine a future revision... will it continue?
