Sending TOSLINK Wirelessly With Lasers

October 2, 2025 by Lewin Day 30 Comments

TOSLINK was developed in the early 1980s as a simple interface for sending digital audio over fiber optic cables, and despite its age, is still featured on plenty of modern home entertainment devices. As demonstrated by [DIY Perks], this old tech can even be taught some new tricks — namely, transmitting surround sound wirelessly.

Often, a TOSLINK stream is transmitted with a simple LED. [DIY Perks] realized that the TOSLINK signal could instead be used to modulate a cheap red laser diode. This would allow the audio signal to be sent wirelessly through the open air for quite some distance, assuming you could accurately aim it at a TOSLINK receiver. The first test was successful, with the aid of a nifty trick, [DIY Perks] filled the open TOSLINK port with a translucent plastic diffuser to make a larger target to aim at.

The rest of the video demonstrates how this technique can be used for surround sound transmission without cables. [DIY Perks] whipped up a series of 3D printed ceiling mirror mounts that could tidily bounce laser light for each surround channel to each individual satellite speaker.

It’s a very innovative way to do surround sound. It’s not a complete solution to wiring issues—you still need a way to power each speaker. Ultimately, though, it’s a super cool way to run your home theater setup that will surely be a talking point when your guests notice the laser mirrors on the ceiling.

We’ve seen some other stealthy surround sound setups before, too.

Continue reading “Sending TOSLINK Wirelessly With Lasers” →

A violet laser beam is shown expanding outward from a diode in a darkened room and illuminating the back of a man's hand.

Driving A Laser At 200 Volts For Nanoseconds

September 30, 2025 by Aaron Beckendorf 26 Comments

If there’s one lesson to be learned from [Aled Cuda]’s pulsed laser driver, it’s that you can treat the current limits on electronic components as a suggestion if the current duration is measured in nanoseconds.

The components in question are a laser diode and an NPN transistor, the latter of which operates in avalanche mode to drive nanosecond-range pulses of high current through the former. A buck-boost converter brings a 12 volt power supply up to 200 volts, which then passes through a diode and into the avalanche transistor, which is triggered by an external pulse generator. On the other side of the transistor is a pulse-shaping network of resistors and capacitors, the laser diode, and a parallel array of low-value resistors, which provide a current monitor by measuring the voltage across them. There is an optoisolator to protect the pulse generator from the 200 volt lines on the circuit board, but for simplicity’s sake it was omitted from this iteration; there is some slight irony in designing your own laser driver for the sake of the budget, then controlling it with “a pulse generator we don’t mind blowing up.” We can only assume that [Aled] was confident in his work.

The video below details the assembly of the circuit board, which features some interesting details, such as the use of a transparent solder mask which makes the circuit layout clear while still helping to align components during reflow. The circuit did eventually drive the diode without destroying anything, even though the pulses were probably 30 to 40 watts. A pulse frequency of 360 hertz gave a nice visual beating effect due to small mismatches between the pulse frequency of the driver and the frame rate of the camera.

This isn’t the first laser driver to use avalanche breakdown for short, high-power pulses, but it’s always good to see new implementations. If you’re interested in further high-speed electronics, we’ve covered them in more detail before.

Continue reading “Driving A Laser At 200 Volts For Nanoseconds” →

Fire Extinguishers, Optical Density Ratings And Safely Using Home Lasers

September 19, 2025 by Maya Posch 25 Comments

Ski goggle type laser safety lenses may look dorky, but they leave no gaps and fit around glasses. (Credit: FauxHammer, YouTube)

After [Ross] from FauxHammer miniature model fame got lured into reviewing laser engravers and similar via the Bambu Lab H2D’s laser module, he found himself getting slightly nervous about the whole ‘safety’ aspect of these lasers. After all, lasers can not only light stuff on fire, but it’s a well-known fact that even reflected laser light can be sufficient to cause permanent damage to your retinas. Or worse.

Since your eyes generally do not regenerate, it makes sense to get caught up on laser safety before turning on one of those plentiful-and-increasingly-affordable home laser systems for engraving and/or cutting.

While the issue of stuff catching on fire is readily solved by having a good CO2 extinguisher – and plan B options – at the ready, for safety glasses it’s significantly more complex. There’s not just the issue of finding glasses that block the wavelength of the laser system that you are using, but also with the right optical density (OD) rating. Every mm of the safety lens material can attenuate a certain amount of laser light at the given wavelength, so the OD rating of your laser safety goggles need to match the laser’s power output level, or you might be living with a false sense of security.

Finally, there is the issue of the smoke and fumes produced by these lasers as they obliterate the target material. Much of what is in this smoke you do not want to breathe in, even ignoring long-term dust and VOC exposure issues, so having a solid fume extraction setup and PPE as necessary are absolute necessities. As [Ross] puts it, you don’t want to breathe in the smell of regret today, for your future self to reflect on a decade from now.

Work safe, work smart, don’t become the subject of a laser safety PSA.

Continue reading “Fire Extinguishers, Optical Density Ratings And Safely Using Home Lasers” →

Engrave A Cylinder Without A Rotary Attachment? No Problem!

July 26, 2025 by Donald Papp 3 Comments

Laser-engraving a cylindrical object usually requires a rotary attachment, which is a motorized holder that rotates a cylindrical object in sync with the engraver. But [Samcraft] shows that engraving all around a mug can be done without a motorized rotary holder.

Separating a design into elements thin enough to engrave individually without losing focus is the key.

The basic idea is to split the design into a number of separate engraving jobs, each containing one element of the overall design, then setting the mug into a 3D printed jig and manually rotating it between jobs. To demonstrate, [Samcraft] selects a series of line-art flowers and plants which are ideal for this approach because there’s no need to minutely register the individual engravings with one another.

What about focus? [Samcraft] found that a design up to 45 mm wide could be engraved onto the curved surface of his mug before focus suffers too much. It’s true that this technique only works with certain types of designs — specifically those with individual elements that can be separated into tall and thin segments — but the results are pretty nice.

Laser engravers are a very serious potential eye hazard, and we are not delighted to see the way the shield around [Samcraft]’s engraver cannot close completely to accommodate the mug while the laser is active. But we’re going to assume [Samcraft] has appropriate precautions and eye protection in place off-camera, because laser radiation and eyeballs absolutely do not belong together, even indirectly.

Continue reading “Engrave A Cylinder Without A Rotary Attachment? No Problem!” →

Blu-ray Won, But At What Cost?

July 16, 2025 by John Elliot V 73 Comments

Over on their substack [ObsoleteSony] has a new article: The Last Disc: How Blu-ray Won the War but Lost the Future.

In this article the author takes us through the history of Blu-ray media and how under Sony’s stewardship it successfully defeated the competing format of the time, HD DVD. Sony started behind the eight ball but through some deft maneuvering managed to come out on top. Perhaps the most significant contributing factor was the inclusion of Blu-ray drives in the PlayStation 3.

The person leading the Blu-ray initiative for Sony was Masanobu Yamamoto, whose legacy was the compact disc. What was needed was a personal media format which could deliver for high-definition 1080p video. As the DVD format did not have the storage capacity required, new formats needed to be developed. The enabling technology for both Blu-ray and HD DVD media was the blue laser as it allowed for more compact encoding.

Sony’s Blu-ray format became the dominating format for high-definition personal media…just as physical media died.

Thanks to [Stephen Walters] for writing in about this one.

A Pi-Based LiDAR Scanner

April 18, 2025 by Bryan Cockfield 30 Comments

Although there are plenty of methods for effectively imaging a 3D space, LIDAR is widely regarded as one of the most effective methods. These systems use a rapid succession of laser pulses over a wide area to create an accurate 3D map. Early LIDAR systems were cumbersome and expensive but as the march of time continues on, these systems have become much more accessible to the average person. So much so that you can quickly attach one to a Raspberry Pi and perform LiDAR imaging for a very reasonable cost.

This software suite is a custom serial driver and scanning system for the Raspberry Pi, designed to work with LDRobot LIDAR modules like the LD06, LD19, and STL27L. Although still in active development, it offers an impressive set of features: real-time 2D visualizations, vertex color extraction, generation of 360-degree panoramic maps using fisheye camera images, and export capabilities for integration with other tools. The hardware setup includes a stepper motor for quick full-area scanning, and power options that include either a USB battery bank or a pair of 18650 lithium cells—making the system portable and self-contained during scans.

LIDAR systems are quickly becoming a dominant player for anything needing to map out or navigate a complex 3D space, from self-driving cars to small Arduino-powered robots. The capabilities a system like this brings are substantial for a reasonable cost, and we expect to see more LiDAR modules in other hardware as the technology matures further.

Thanks to [Dirk] for the tip!

Engraving of Alexander Graham Bell's photophone, showing the receiver and its optics

Replica Of 1880 Wireless Telephone Is All Mirrors, No Smoke

April 15, 2025 by Tyler August 18 Comments

If we asked you to name Alexander Graham Bell’s greatest invention, you would doubtless say “the telephone”; it’s probably the only one of his many, many inventions most people could bring to mind. If you asked Bell himself, though, he would tell you his greatest invention was the photophone, and if the prolific [Nick Bild] doesn’t agree he’s at least intrigued enough to produce a replica of this 1880-vintage wireless telephone. Yes, 1880. As in, only four years after the telephone was patented.

It obviously did not catch on, and is not the sort of thing that comes to mind when we think “wireless telephone”. In contrast to the RF of the 20th century version, as you might guess from the name the photophone used light– sunlight, to be specific. In the original design, the transmitter was totally passive– a tube with a mirror on one end, mounted to vibrate when someone spoke into the open end of the tube. That was it, aside from the necessary optics to focus sunlight onto said mirror. [Nick Bild] skips this and uses a laser as a handily coherent light source, which was obviously not an option in 1880. As [Nick] points out, if it was, Bell certainly would have made use of it.

Bell's selenium-based photophone receiver. — The photophone receiver, 1880 edition. Speaker not pictured.

The receiver is only slightly more complex, in that it does have electronic components– a selenium cell in the original, and in [Nick’s] case a modern photoresistor in series with a 10,000 ohm resistor. There’s also an optical difference, with [Nick] opting for a lens to focus the laser light on his photoresistor instead of the parabolic mirror of the original. In both cases vibration of the mirror at the transmitter disrupts line-of-sight with the receiver, creating an AM signal that is easily converted back into sound with an electromagnetic speaker.

The photophone never caught on, for obvious reasons — traditional copper-wire telephones worked beyond line of sight and on cloudy days–but we’re greatful to [Nick] for dredging up the history and for letting us know about it via the tip line. See his video about this project below.

The name [Nick Bild] might look familiar to regular readers. We’ve highlighted a few of his projects on Hackaday before.

Continue reading “Replica Of 1880 Wireless Telephone Is All Mirrors, No Smoke” →