Pocket-sized Test Pattern Generator Helps Check Those CRTs

[Nicholas Murray]’s Composite Test Pattern Generator is a beautifully-made, palm-sized tool that uses an ESP32-based development board to output different test patterns in PAL/NTSC. If one is checking out old televisions or CRTs, firing up a test pattern can be a pretty handy way to see if the hardware is healthy or not.

The little white add-on you see attached to the yellow portion is a simple circuit (two resistors and an RCA jack) that allows the microcontroller to output a composite video signal. All one needs to do is power on the device, then press the large button to cycle through test patterns. A small switch on the side toggles between NTSC and PAL video formats. It’s adorable, and makes good use of the enclosures that came with the dev board and proto board.

In a pinch a hacker could use an original Raspberry Pi, because the original Pi notably included a composite video output. That feature made it trivial to output NTSC or PAL video to a compatible display. But [Nicholas]’s device has a number of significant advantages: it’s small, it’s fast, it has its own battery and integrated charger, and the little color screen mirroring the chosen test pattern is a great confirmation feature.

This is a slick little device, and it’s not [Nicholas]’s first test pattern generator. He also created a RP2040-based unit with a VGA connector, the code of which inspired a hacker’s home-grown test pattern generator that was used to service a vintage arcade machine.

A grey and blue coreXY 3D printer is shown, with a small camera in place of its hotend. On the print bed is a ChArUco pattern, a grid of square tiles containing alternating black fill and printed patterns.

Calibrating A Printer With Computer Vision And Precise Timing

[Dennis] of [Made by Dennis] has been building a Voron 0 for fun and education, and since this apparently wasn’t enough of a challenge, decided to add a number of scratch-built improvements and modifications along the way. In his latest video on the journey, he rigorously calibrated the printer’s motion system, including translation distances, the perpendicularity of the axes, and the bed’s position. The goal was to get better than 100-micrometer precision over a 100 mm range, and reaching this required detours into computer vision, clock synchronization, and linear algebra.

To correct for non-perpendicular or distorted axes, [Dennis] calculated a position correction matrix using a camera mounted to the toolhead and a ChArUco board on the print bed. Image recognition software can easily detect the corners of the ChArUco board tiles and identify their positions, and if the camera’s focal length is known, some simple trigonometry gives the camera’s position. By taking pictures at many different points, [Dennis] could calculate a correction matrix which maps the printhead’s reported position to its actual position.

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The Miracle Of Color TV

We’ve often said that some technological advancements seemed like alien technology for their time. Sometimes we look back and think something would be easy until we realize they didn’t have the tools we have today. One of the biggest examples of this is how, in the 1950s, engineers created a color image that still plays on a black-and-white set, with the color sets also able to receive the old signals. [Electromagnetic Videos] tells the tale. The video below simulates various video artifacts, so you not only learn about the details of NTSC video, but also see some of the discussed effects in real time.

Creating a black-and-white signal was already a big deal, with the video and sync presented in an analog AM signal with the sound superimposed with FM. People had demonstrated color earlier, but it wasn’t practical for several reasons. Sending, for example, separate red, blue, and green signals would require wider channels and more complex receivers, and would be incompatible with older sets.

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How Big Is Your Video Again? Square Vs Rectangular Pixels

[Alexwlchan] noticed something funny. He knew that not putting a size for a video embedded in a web page would cause his page to jump around after the video loaded. So he put the right numbers in. But with some videos, the page would still refresh its layout. He learned that not all video sizes are equal and not all pixels are square.

For a variety of reasons, some videos have pixels that are rectangular, and it is up to your software to take this into account. For example, when he put one of the suspect videos into QuickTime Player, it showed the resolution was 1920×1080 (1350×1080). That’s the non-square pixel.

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Converting A 1980s Broadcast Camera To HDMI

Although it might seem like there was a sudden step change from analog to digital sometime in the late 1900s, it was actually a slow, gradual change from things like record players to iPods or from magnetic tape to hard disk drives. Some of these changes happened slowly within the same piece of hardware, too. Take the Sony DXC-3000A, a broadcast camera from the 1980s. Although it outputs an analog signal, this actually has a discrete pixel CCD sensor capturing video. [Colby] decided to finish the digitization of this camera and converted it to output HDMI instead of the analog signal it was built for.

The analog signals it outputs are those that many of us are familiar with, though: composite video. This was an analog standard that only recently vanished from consumer electronics, and has a bit of a bad reputation that [Colby] thinks is mostly undeserved. But since so many semi-modern things had analog video outputs like these, inspiration was taken from a Wii mod chip that converts these consoles to HDMI. Unfortunately his first trials with one of these had confused colors, but it led him to a related chip which more easily outputted the correct colors. With a new PCB in hand with this chip, a Feather RP2040, and an HDMI port the camera is readily outputting digital video that any modern hardware can receive.

Besides being an interesting build, the project highlights a few other things. First of all, this Sony camera has a complete set of schematics, a manual meant for the end user, and almost complete user serviceability built in by design. In our modern world of planned obsolescence, religious devotion to proprietary software and hardware, and general user-unfriendliness this 1980s design is a breath of fresh air, and perhaps one of the reasons that so many people are converting old analog cameras to digital instead of buying modern equipment.

Tiny Little TV Runs On ESP32

Few of us keep big old cathode ray tubes in the house anymore, but we can still appreciate the form factor of the classic TV. Indeed, the Tinytron from [t0mg] is a neat little tchotchke in this vein — a miniature TV that you could just about fit on a keyring.

[t0mg] wanted this project to be quick and easy to put together. It starts with an ESP32-S3-LCD-1.69 from Waveshare. It’s an all-in-one dev module which combines the microcontroller with a small screen right out of the box. You just have to solder a single six pin header to hook it up with an SD card reader and battery, and you’re done with the electronics. Even the case is a cinch to build, with four 3D printed components that can be spat out of a Prusa MK4S in just half an hour. Programming it can be done via a web browser. Just about the only thing it’s missing is a speaker — this TV is video only.

To watch things on the Tinytron, you just have to prepare them properly and drop them on the SD card. [t0mg] provides a web page for transcoding the video files, although you can do it yourself locally with ffmpeg if you prefer.

If you’re looking for a silly gift for a TV-obsessed friend, you could probably whip up a Tinytron in a couple hours or less. It reminds us of another great project, the tiny Simpsons replica TV that endlessly plays the greatest cartoon on Earth.

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A 3D Printed 16mm Movie Camera

The basic principles of a motion picture film camera should be well understood by most readers — after all, it’s been well over a hundred years since the Lumière brothers wowed 19th century Paris with their first films. But making one yourself is another matter entirely, as they are surprisingly complex and high-precision devices. This hasn’t stopped [Henry Kidman] from giving it a go though, and what makes his camera more remarkable is that it’s 3D printed.

The problem facing a 16mm movie camera designer lies in precisely advancing the film by one frame at the correct rate while filming, something done in the past with a small metal claw that grabs each successive sprocket. His design eschews that for a sprocket driven by a stepper motor from an Arduino. His rotary shutter is driven by another stepper motor, and he has the basis of a good camera.

The tests show promise, but he encounters a stability problem, because as it turns out, it’s difficult to print a 16mm sprocket in plastic without it warping. He solves this by aligning frames in post-processing. After fixing a range of small problems though, he has a camera that delivers a very good picture quality, and that makes us envious.

Sadly, those of us who ply our film-hacking craft in 8mm don’t have the luxury of enough space for a sprocket to replace the claw.

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