I never intended to join the cutting edge of electromechanical television. I just wanted to make a nice clock. But sometimes you have to go where the engineering takes you, and in my case it took me to the Scanwheel, a pocket-size wide-screen electromechanical TV with a resolution of 4,096 by 20 pixels. Yup, that’s 4K by 20.

The 3D-printed drum [top] is spun by a motor controlled by a driver board [second row, from top]. The driver board, in turn, is controlled by a Raspberry Pi Pico [middle], which also controls the LEDs [second row, from bottom], which are mounted in the 3D-printed casing [bottom] so that the holes pass over them as the drum turns.James Provost

Electromechanical television was the first form of practical television, developed by John Logie Baird in the 1920s. He used a so-called Nipkow disk, which has a spiral of holes punched through it. As the disk rotates, the holes pass one by one in front of a light source. By varying the brightness of the light as a hole travels across it, you can draw one scan line of a video frame. Spin the disk fast enough, and persistence of vision makes it look like an entire frame is being displayed simultaneously. Commercial electromechanical TV sets were produced in the United Kingdom, with regular broadcasts provided by the BBC in the 1930s.

Although cathode-ray tubes replaced electromechanical televisions in the 1940s, hobbyists have continued to build them and even improve on the original technology. For example, in the June 2022 installment of IEEE Spectrum’s Hands On, Markus Mierse presented a desktop-size 3D-printed color version.

I built an electromechanical display myself some years ago, but it had a traditional design with a Nipkow disk made from a vinyl record with holes drilled in it. Recently I started tinkering with electromechanical TV again as an outgrowth of my YouTube channel. There I’ve been focusing on developing volumetric displays, which create 3D pixels floating within a volume of space. In particular, I was interested in borrowing some ideas from plenoptic cameras, which use pinholes and lenses to capture multidimensional light fields of samples.

I wondered if I could run the process in reverse, to create light fields rather than capture them. I often explore ideas in two dimensions before expanding to the third, so I thought I’d first demonstrate a 2D display. I decided to make an electromechanical device into a clock. After all, you don’t need high resolution to display digits.

How Does the Scanwheel Display Work?

Thinking about the display as a clockface pushed me toward some key ideas. First, instead of having just one display area, I would use five light sources to create multiple areas—four to represent hours and minutes, and a central area for a separator that would blink each second. Second, to align the digits in a readable row rather than have them spread around an arc, I swapped the Nipkow disk for an established alternative: a Nipkow drum.

With a drum, the holes run along the curved cylindrical surface in a stair-step pattern. This means they always trace a straight line from the perspective of a viewer looking from the side, so the clock’s digits would be horizontally aligned.

“In tests, I’ve pushed the horizontal resolution to more than 8,000 pixels.”

These two decisions turned out to be key to achieving both miniaturization and high horizontal resolution. A disk needs a fairly wide diameter so that the scan lines aren’t ridiculously curved. But curvature isn’t a problem with a drum. A drum can be much smaller than a disk that has the same number of scan lines. (And unlike in the 1920s, packing multiple light sources close together inside a small drum isn’t a problem with modern LEDs.) I settled on a 6-centimeter-wide drum, turning the device from desktop-size to something you could carry in your pocket.

I then realized my five display zones could work in concert to create one single wide screen. Because it’s possible to modulate the brightness of an LED at very high rates, the horizontal resolution can also be very high. My system currently has 4K horizontal resolution, and this is primarily limited by the amount of onboard memory I have available. This memory holds the buffer that stores pixel data for each frame before it is read out to the LEDs and displayed. In tests, I’ve pushed the horizontal resolution to more than 8,000 pixels.

Despite the Scanwheel’s low vertical resolution—at 20 pixels, it has fewer scan lines than Baird’s 30-line televisions—its high horizontal resolution makes the legibility of the display surprisingly good: I can display not just crude digits but video streamed into the frame buffer.

Using the RP2040 Chip’s Special Silicon

That frame buffer lives on a Raspberry Pi Pico microcontroller board, based around the RP2040 microcontroller. The RP2040 is ideal for this project because of the chip’s dedicated PIO silicon. PIO stands for programmable input/output, and it’s a block of four coprocessors that uses a very limited instruction set. Each coprocessor can be set up to chew through input/output streams completely independently of the RP2040’s two CPU cores.

The first mechanical TVs used disks, which had to be wide to minimize image distortion but allowed bulky light sources. With small, modern light sources, a smaller drum can create images with minimal distortion.James Provost

It’s thanks to the PIO that I’m able to keep up with the spinning drum and modulate each of the five LEDs simultaneously as holes pass over them, a task complicated by the fact that the center LED is not a monochrome LED, but a color LED with separate red, green, and blue channels. In fact, the PIO does nearly all the work, pulling data from the frame buffer and controlling the LEDs and the spinning of the drum. The code running on the CPU (written in MicroPython) is primarily responsible for setting up the PIO and then leaving well enough alone.

A stepper motor connected to a driver board spins the drum, with power provided by the USB jack on the Pi Pico. All the Pi Pico has to do controlwise is send the board a pulse to incrementally advance the drum’s position once every millisecond. Video data is streamed into the Pi Pico via a network interface. You can set up the Scanwheel to mirror a portion of your computer’s screen, or to act as a separate display.

The casing, including the drum, is 3D printed. Now for a neat bit: In the Scanwheel’s GitHub repository at https://github.com/AncientJames/Scanwheel/tree/main, alongside all the other files you’ll need to make this project yourself, there’s an OpenSCAD file that generates the 3D-print file for the drum based on adjustable parameters. This means you can easily make a taller drum and add more scan lines, or try other customizations for your very own portable electromechanical display. You can even use it as a clock!

Hugging Face unveiled the Microduck on Thursday, a cute little duck-like robot that sells for $399 — and ships before Christmas. 

Clem Delangue, CEO of Hugging Face, said the Microduck is an “open-source robot you can teach new tricks with reinforcement learning.” The 25-centimeter-tall duck can waddle, pick things up with its beak (up to 800 grams), get back up when it falls, crouch, and even roller skate.

“Welcome to the era of open-source affordable robots to democratize physical AI and world models!” Delangue said. 

The rapid scaling of robotaxis over the last two years has come with a hidden human cost. 

Test drivers for Waymo and Zoox sustained more than two dozen injuries in 2024 and 2025 from hard braking or other sudden movements made by the autonomous vehicles, according to a TechCrunch review of data submitted to the Occupational Safety and Health Administration. 

These test drivers, who put autonomous vehicles through their paces on public roads, have suffered sprains, strains, whiplash, and more, according to OSHA data and interviews with former and current workers. Some have been sidelined for weeks or months.

Transdev, which employs and manages Waymo’s test drivers, reported 16 injuries tied to Waymo depot locations in three cities that were caused by the autonomous software braking hard or swerving suddenly. Zoox reported as many as eight worker injuries linked to hard braking. 

Other autonomous vehicle companies do not appear in the dataset, though it’s possible they’re exempt. The Zoox and Waymo injuries appear because the companies classify themselves as taxi, limo, or transit services, which OSHA subjects to greater disclosure because they’re “higher-hazard” industries. OSHA also only requires establishments with 100 or more employees in these industries to make this information public, meaning test drivers in newer cities where operations haven’t scaled may have been injured on the job without appearing in this dataset. 

TechCrunch was unable to learn whether Waymo or Transdev logged any new injuries in 2026. OSHA does not require companies to submit annual data until the following year as part of the agency’s Injury Tracking Application.  

In Zoox’s case, injuries are still happening, according to sources who spoke to TechCrunch on condition of anonymity.  

Two current and three former Zoox contractors told TechCrunch that the company’s test fleet vehicles — modified Toyota Highlander SUVs equipped with its self-driving system — were still braking hard and abruptly as recently as July. Three of those contractors said workers are still getting hurt. The workers were granted anonymity to discuss private operations. 

Zoox declined to answer specific questions about the injuries it reported last year or the claims contractors made to TechCrunch about the continued hard-braking issues. The company said it follows necessary reporting requirements and takes injuries seriously. 

Zoox also said hard-braking incidents are sometimes unavoidable and that the injuries reported last year represent a small percentage of the millions of miles its test fleet traveled. 

Waymo also declined to answer questions about the injuries reported to OSHA.  

“The safety of our riders, road users, and team is of paramount importance,” Waymo told TechCrunch. “As part of the process of responsibly deploying fully autonomous vehicles, we have driven tens of millions of miles with human operators behind the wheel. This is part of our ongoing validation process and learnings from these trips are integrated into the service.” 

Transdev declined to comment.  

More miles, more injuries 

While Waymo has spent more than a decade developing its self-driving cars, it wasn’t until 2025 that it really started to scale. The company started offering rides in new cities and began mapping and testing in others, growing its commercial fleet to more than 1,500 vehicles by May 2025.  Today, that fleet is more than 3,500 vehicles.

Waymo doesn’t break out how many vehicles it uses just for testing. But the amount of autonomous vehicle testing almost certainly increased as the company expanded its service areas and started to familiarize itself with entirely new locations.  

Test driver injuries increased, too.  

Transdev reported five Waymo test driver injuries in 2024 across San Francisco, Los Angeles, and Phoenix. One was related to hard braking, while the other four were related to erratic vehicle behavior.  

In one case, a test driver reported that the car “suddenly backed up” while parking itself and “whipped the steering wheel,” catching his left hand and bending it “to the point he heard a crack in his wrist.” The employee spent more than two months away from work as a result. 

The number of injuries jumped to 11 in those three markets in 2025, and hard braking was the cause of nearly all of them. Last September, a test driver in Phoenix wound up having to spend 157 days away from work after their vehicle “made an exaggerated breaking [sic] event without any obstruction.” At least two other injury reports specifically mention that the hard braking happened for no apparent reason.  

The only injury report from 2025 that offers a reason for a hard-braking event involved an incident that happened in August in Los Angeles. The employee reported that “some kids were playing in the pathway.” The Waymo robotaxi stopped hard enough that the worker spent 175 days away from their job.  

“Software braked harshly” 

The Zoox contractors said hard braking — or “brake jabs,” as they are referred to internally — can happen multiple times on a single test drive, sometimes in the same location. They can happen at any speed, though higher-velocity braking incidents typically take a harsher toll on the body, the workers said.  

The braking often happens when the autonomous driving system detects — or mistakenly detects — debris of some kind on the road, they said. 

The scariest incidents, the contractors said, are when a test vehicle experiences a “nogo” — internal code for an entire system shutdown that often leads to a brake jab.  

“You could be going 45 miles per hour and the car will enact a nogo, and suddenly you’re being whipped forward in the middle of the street, in traffic, and you need to be able to take over quickly,” one said. 

This behavior shows up repeatedly in the injury reports Zoox submitted to OSHA.  

On January 5, 2025, a Zoox test vehicle was driving autonomously in San Francisco when it abruptly slammed on the brakes. The “harsh” stop, as Zoox described it, injured the shoulder and upper arm of a contractor who was inside the SUV, leaving the worker on restricted duty for 16 days. 

Later that month, another driver was hurt after a Zoox test vehicle made an “unexpected” stop, injuring their neck and leaving them with a swollen shoulder. It took the contractor eight days to return to work without restrictions. 

Most of the Zoox-reported injuries appear to have happened to workers who sit in the driver’s seat of the SUVs. The company also reported an injury to an instructor who trains the test drivers. That injury took place on June 3 in San Francisco, when the test vehicle’s “software braked harshly,” causing the instructor in the back seat to report “sharp pain in lower right ribs and tightness in left shoulder upon returning to base.”  

The injured instructor reported additional injuries to the spine and pelvis, though their work restrictions lasted only four days, according to the data.  

Seven of the eight entries explicitly mention hard braking, nogos, or brake jabs. The eighth injury involved a worker who was sidelined for the longest amount of time — 46 days — and who reported “extreme back pain” after operating a test vehicle in Las Vegas in May 2025. Zoox wrote that the worker said they “were not sure if it was related to the behavior of the vehicle in autonomy or not but they said it hurts them to drive as well as take deep breaths,” and attributed the injury to a “vehicle maneuver.”  

Zoox is dealing with these hard-braking issues as it finally begins offering a true commercial robotaxi service in a bid to compete with Waymo. The Amazon-owned company started charging for rides in its purpose-built robotaxi for the first time this month in Las Vegas. It offers free rides in San Francisco and is testing in Atlanta, Austin, Dallas, Los Angeles, Phoenix, Seattle, and Washington, D.C. 

Four of the injuries Zoox reported in 2025 happened after the company issued a recall meant to resolve a year-long federal investigation into the tendency of its autonomous vehicles to brake unexpectedly. Zoox told TechCrunch the recall addressed an extremely narrow braking behavior and said the later incidents — and any resulting injuries — are unrelated to the software fix. 

Two of the people who spoke to TechCrunch said that braking can be challenging even when manually driving the Zoox test cars because of the extra weight of the self-driving sensor suite. Test drivers are trained to brake with the extra weight, they said, though they added that minor injuries can be sustained even during that training process. 

It’s hard to know if Zoox is experiencing hard-braking incidents with any regularity in its purpose-built vehicles, which do not have traditional controls such as a steering wheel or pedals. They either operate unoccupied or carry passengers who mostly aren’t employees – meaning any injuries wouldn’t be reported to OSHA.  

Zoox has reported two robotaxi crashes to the National Highway Traffic Safety Administration in the last eight months in which hard braking for debris resulted in the purpose-built vehicles being rear-ended. The company’s descriptions of the crashes don’t specify what debris was spotted in either case.