[Johan] has slipped down the rabbit hole of making musical instruments. His poison? Laser harp MIDI controllers. Having never made one before, he thought he would start small and then iterate using what he learned. Fortunately for us, [Johan] documented the process over on .io, essentially creating a step-by-step guide for building a simple but powerful 16-note laser harp.
Laser Harp I is built around a Teensy 3.2 and, of course, lasers pointed at LDRs. [Johan] used fairly low-power laser modules, which are slightly less blinding if you accidentally look at them for a second, but should still be taken seriously. He added four potentiometers to control the sensitivity, scale, octave, and the transposition. The sensitivity pot essentially accounts for the ambient light in the room. Although it only has 16 notes, Laser Harp I is ready to rock with over 30 different scales to choose from. Check out the brief demo that [Johan] put up on his Instagram.
If at first you don’t succeed, try, try, and try again. This is especially true when your efforts involve a salvaged record player, a laser cutter, and He-Man. Taking that advice to heart, maniac maker extraordinaire [William Osman] managed to literally burn music onto a CD.
Considering the viability of laser-cut records is dubious — especially when jerry-built — it took a couple frustrating tests to finally see results, all the while risking his laser’s lens. Eventually, [Osman]’s perseverance paid off. The lens is loosely held by a piece of delrin, which is itself touching a speaker blaring music. The vibrations of the speaker cause the lens to oscillate the focal point of the laser into a wavelength that is able to be played on a record player. You don’t get much of the high-end on the audio and the static almost drowns out the music, but it is most definitely a really shoddy record of a song!
Vinyl aficionados are certainly pulling their hair out at this point. For the rest of us, if you read [Jenny’s] primer on record players you’ll recognize that a preamplifier (the ‘phono’ input on your amp) is what’s missing from this setup and would surely yield more audible results.
The star turn of most hackspaces and other community workshops is usually a laser cutter. An expensive and fiddly device that it makes much more sense to own collectively than to buy yourself.
This isn’t to say that laser cutters are outside the budget of the experimenter though, we’re all familiar with the inexpensive table-top machines from China. Blue and white boxes that can be yours for a few hundred dollars, and hold the promise of a real laser cutter on your table.
Owning one of these machines is not always smooth sailing though, because their construction and choice of components are often highly variable. A thorough check and often a session of fixing the non-functional parts is a must before first power-on.
[Extreme Electronics] bought one, and in a series of posts documented the process from unboxing to cutting. Starting with a full description of the machine and what to watch for out of the box, then a look at the software. A plugin for Corel Draw was supplied, along with a dubious copy of Corel Draw itself. Finally we see the machine in operation, and the process of finding the proper height for beam focus by cutting an inclined plane of acrylic.
The series rounds off with a list of useful links, and should make interesting reading for anyone, whether they are in the market for a cutter or not.
We’ve seen a lot of interest in LSM (LASER Scanning Microscopes) lately. [Stoppi71] uses an Arduino, a CD drive, and–of all things–two speakers in his build. The speakers are used to move the sample by very small amounts.
The speakers create motion in the X and Y axis depending on the voltage fed to them via a digital analog converter. [Stoppi71] claims this technique can produce motion in the micron range. His results seem to prove that out. You can see a video about the device, below.
We don’t know what cats see when they see a red laser beam, but we know it isn’t what we see. The reaction, at least for many cats — is instant and extreme. Of course, your cat expects you to quit your job and play with it on demand. While [fluxaxiom] wanted to comply, he also knew that no job would lead to no cat food. To resolve the dilemma, he built an automated cat laser. In addition to the laser module, the device uses a few servos and a microcontroller in a 3D printed case. You can see a video, below. Dogs apparently like it too, but of course they aren’t the reason it was built.
If you don’t have a 3D printer, you can still cobble something together. The microcontroller is an Adafruit Pro Trinket, which is essentially an Arduino Pro Mini with some extra pins and a USB port.
Pour yourself a nice hot cup of tea, because [iliasam]’s latest work on a laser rangefinder (in Russian, translated here) is a long and interesting read. The shorter version is that he got his hands on a broken laser security scanner, nearly completely reverse-engineered it, got it working again, put it on a Roomba that was able to map out his apartment, and then re-designed it to become a tripod-mounted, full-room 3D scanner. Wow.
The scanner in question has a spinning mirror and a laser time-of-flight ranger, and is designed to shut down machinery when people enter a “no-go” region. As built, it returns ranges along a horizontal plane — it’s a 2D scanner. The conversion to a 3D scanner meant adding another axis, and to do this with sufficient precision required flipping the rig on its side, salvaging the fantastic bearings from a VHS machine, and driving it all with the surprisingly common A4988 stepper driver and an Arduino. A program on a PC reads in the data, and the stepper moves another 0.36 degrees. The results speak for themselves.
This isn’t [iliasam]’s first laser-rangefinder project, naturally. We’ve previously featured his homemade parallax-based ranger for use on a mobile robot, which is equally impressive. What amazes us most about these builds is the near-professional quality of the results pulled off on a shoestring budget.
Like the original, [noniq]’s version is laser cut and engraved, and uses some 3D printed parts. But it does away with the fasteners (that’s 60 pairs of nuts and bolts), and instead uses neodymium magnets to make all the triangle pieces snap together to form the icosahedron globe. The hinges are simply some pieces of gaffer-tape.
This design improvement creates a cleaner globe and also addresses some of the concerns posted in the comments of the earlier build. The design files are available for download on [noniq]’s blog — you need to 3D print some magnet holders and stopper plates, and laser cut the 20 triangle tiles. The stopper plates help ensure that the angle between tiles when it is put together is limited to 138 degrees, making it easier to assemble the globe.
Check out the video after the break to hear the satisfying “thunk” of neodymium magnets snapping together.