Laser Projector Built From An Old Hard Drive

May 12, 2023 by 41 Comments

Spinning hard drives are being phased out of most consumer-grade computers in favor of faster technology like solid-state drives and their various interfaces. But there’s still millions of them in circulation that will eventually get pulled from service — so what do we do with them? If you’ve got one that would otherwise be going in the garbage, they can be turned into some other interesting devices like this laser text projector.

Even the slowest drives spin at around 5000 RPM, which is perfect for this type of application. The device works by mounting twelve mirrors, each at a slightly different angle, on a drum which is spun by the drive’s motor. Bouncing a laser off of the spinning drum results in a projection of twelve horizontal lines. By rapidly switching the laser on and off depending on which mirror it’s pointing at, the length of each line can be controlled.

Thanks to persistence of vision, that allows you to show text on the surface that the laser is projected on. At speeds this high, it took [Ben] of Ben Makes Everything quite a few iterations to get it to a usable space. From sensors that were too slow to lasers not bright enough to 3D prints that were not accurate enough, he goes through the design of his build and the process in excellent detail.

After solving all of the problems including building his own constant-current laser power supply, and burning up a few laser diodes in the process, [Ben] has a laser projector capable of displaying readable text at a great distance which is also portable, running on a 12 V power supply. There are some possible areas of improvement that he notes as well, such as an unbalanced 3D printed part causing a bit of a wobble and the Arduino controller not being fast enough for more text. But it’s an impressive project nonetheless, similar to a two-mirror version we saw some time ago but with the ability to display text as well.

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No Home Cinema Is Complete Without A Motorized Projector

April 5, 2023 by 5 Comments

In the home of the future, everything is automated. Some of us are already there, in dwellings fully tricked-out with IoT and smart home devices. But they don’t somehow look as futuristic as a home in which everything is motorized. We don’t know whether this was the intention, but we certainly get a futuristic vibe from [Sam Baker]’s home cinema projector mount. It’s no mere bracket, instead on command the projector descends from concealment in the ceiling on a custom scissor lift mechanism.

A scissor lift is a simple enough mechanism, but since he was 3D printing one that had to withstand the weight of the projector, it took him a while to get it right. Even the lead screw which drives it is also printed, turned by a stepper motor. As the brains of the unit needn’t be particularly accomplished, an Arduino Nano does the job well enough.

It’s fair to say that his projector isn’t the heaviest of models, but the result glides smoothly down from the ceiling for a perfect home cinema experience. We like it.

What’s Inside A Super-Cheap Projector? Not A Lot!

December 18, 2022 by 39 Comments

[Raymond Ma] has a penchant for browsing Aliexpress and purchasing curious pieces of hardware that are as high on promises as they are low on cost. This is a process he aptly sums up with his opening line of “I should have known better, but…” Luckily, these devices all get torn down and analyzed so we can each enjoy and share a little slice of disappointment.

One such item is the $30 USD YT200 mini projector, which at 320×180 is almost as low on pixels as it is on cost. Still, [Raymond] looks inside to find out if there is perhaps more hacking potential than there is image resolution.

The YT200 lacks any kind of normal video input, and the anemic 15 lumen output is brazenly branded as a feature to protect children’s eyes from excessive brightness.

Light from the single LED is collimated with some Fresnel lenses. That light passes through an LCD panel, and from there the image bounces off a mirror and through a focusing lens housed in a spiral guide. Focal adjustments are made with a small lever, and the whole assembly provides just enough friction to prevent the lens from moving out of focus on its own.

The device actually does work fairly well for what it is: a way to play a range of different media types off a connected USB storage device. As long as one is in a dark room, anyway.

[Raymond] hopes to find some alternate use for the device. Might we suggest projecting into a frosted glass globe to create a sort of spherical display? A spooky eye animation on a USB stick might pair well with that.

An RGB laser projector opened up on a workbench

Laser Projector Needs Hardware Hack After Software Mod

December 11, 2022 by 13 Comments

You probably recognize that dreadful feeling when you reboot a gadget after updating its firmware, only to be greeted by a blank screen and an unresponsive device. This apparently happened to the previous owner of a bricked RGB laser projector that [Buy It Fix It] got his hands on: it briefly flashed its laser on power-up but otherwise remained completely dead.

A thorough inspection of the major components didn’t reveal any physical damage, so the issue had to be in software. [Buy It Fix It] managed to connect his Segger J-link programmer to the STM32 main processor and downloaded the contents of its firmware, only to find the remains of a PDF file which seemed to have been accidentally flashed into the chip’s program space. Fixing the device should then just be a matter of restoring the proper firmware, but [Buy It Fix It] wasn’t able to find a copy of it anywhere.

A PCB with a few mod wires on itWhat he did find was Maximus64’s GitHub repository that contained a software mod for a different projector model, as well as its original firmware. Flashing that version didn’t fix [Buy It Fix It]’s projector either, although it did now start to actuate its galvos.

A bit of reverse engineering revealed that the two projectors were very similar from a hardware point of view, but had their laser drivers hooked up to different I/O pins: simply cutting the board traces and soldering some wires to re-route the signals was enough to bring the projector back into a working state.

Having to modify hardware in order to make it fit a piece of software is unfortunate, but sometimes you just have to make do with what you’ve got. If you’ve got no firmware to begin with, then you might even have to write your own from scratch.

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Laser Projector Relies On Steppers Rather Than Galvanometers

November 2, 2022 by 29 Comments

Laser light shows have always been real crowd-pleasers. There’s just something about the frenetic movement of a single point of intensely bright light making fluid animations that really captures the imagination. Large-scale laser shows require a lot of gear, of course, but that doesn’t mean you can’t get in on the fun yourself using something like this homebrew X-Y laser projector.

This is actually [Stanley]’s second pass at a stepper-based DIY projector; we featured his previous build back in 2016. This time around, he wanted to move beyond the “module mix-and-match” style of construction, so rather than use an Arduino and stepper shield, he rolled his own controller PCB to hold an ESP32 and a pair of STSPIN220 stepper drivers. The business end of the new version saw improvements, too — given that he was seeing unwanted softening of corners and curving of straight lines in the first projector’s images, he opted for smaller steppers holding smaller mirrors this time around. There’s also a new 3D printed chassis to hold everything, simplifying the build and keeping the two mirrors in better alignment.

The video below has the build details and some nice footage of the projector in action — it’s hard to go wrong with lasers and smoke. The performance seems pretty good, so the improvements seem to have paid off. And for those of you tapping out your “Should have used galvos” comments below, relax; [Stanley] says he’s thinking about ways to make his own galvanometers for the next version.

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Ultimate Bokeh With A Projector Lens

August 2, 2022 by 22 Comments

Bokeh is a photography term that’s a bit difficult to define but is basically soft, aesthetically pleasing background blur, often used to make a subject stand out. Also called “background separation” or “subject isolation”, achieving it optically requires a fast lens with an aperture below 2.8 or preferably lower. These lenses can get very expensive, but in the video after the break [Matt] from [DIY Perks] blows all the commercially available options out of the water. Using an old episcope projector, he built a photography rig with background separation equivalent to that of a non-existent 35mm f0.4 lens.

Unlike most conventional projectors used to project a prerecorded image, episcopes were used to project an image of physical objects, like books. To use this lens directly in a camera is impossible, due to the size of the imaging circle projected out the back of the lens. At a diameter of 500mm, there is simply no imaging sensor available to capture it. Instead, [Matt] built a projection screen for the image and photographed it from the opposite side with a normal camera.

The projection screen was made by sandwiching a sheet of diffuser film between two sheets of clear acrylic held in a frame of aluminum extrusions. To block out all other light, [Matt] added aluminum shrouds on either side of the screen, which also serves to mount the lens and a camera. The shroud on the lens’ side is mounted on a separate aluminum frame, enabling the image to be focused by adjusting the distance between the screen and lens. Linear rods and bearings on 3D printed mounts allow smooth motion, while a motor-driven lead screw connected to a wired remote does the actual adjustment. The gap between the two halves was covered with bellows made from black paper. Continue reading “Ultimate Bokeh With A Projector Lens” →

Making A Projector Screen Out Of Flex Seal Works Okay, Kinda

June 10, 2022 by 6 Comments

Watching movies on the big screen is fun, but getting out to the cinema or drive-in can be a hassle. It’s possible to get the same experience at home with a little creativity, as shown in this DIY projector screen build by [The Hook Up].

The build started with a giant motorized roller screen designed for a patio. It was scored on the cheap as it was salvaged after removal from its original home. Having seen a screen door turned into a boat with the help of Flex Seal, [The Hook Up] was confident that the flyscreen could be sealed up and used for projection.

Right away, the going got tough. Light applications weren’t really filling in the holes in the flyscreen, while thick applications had major issues with runs. Eventually, the screen was painted with 3 gallons of white Flex Seal and hung up to test.

The runs caused issues, as the lumpy screen texture was distracting when viewing movies. Additionally, the glossy finish was creating unsightly reflections. After some trial and error, the issues were solved by sanding the Flex Seal surface flat and using matte clear spray paint to dull the shine.

The result was a grand projection screen that rolls down at the touch of a button, the likes of which we’ve seen before, though at significant cost. [The Hook Up] readily admitted that the several hundred dollars invested might have been better spent on buying a pre-made screen. Nonetheless, it’s a cool project, and we respect the creator for putting in the work! Video after the break.
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