Old Film Camera Modified For Different Chemistry

August 3, 2023 by 12 Comments

While most photographers have moved on to digital cameras with their numerous benefits, there are a few artists out there still taking pictures with film. While film is among the more well-known analog photographic methods available, there are chemically simpler ways of taking pictures available for those willing to experiment a little bit. Cyanotype photography is one of these methods, and as [JGJMatt] shows, it only takes a few commonly available chemicals, some paper, and a slightly modified box camera to get started.

Cyanotype photography works by adding UV-reactive chemicals to paper and exposing the paper similarly to how film would be exposed. The photographs come out blue wherever the paper wasn’t exposed and white where it was. Before mixing up chemicals and taking photos, though, [JGJMatt] needed to restore an old Kodak Brownie camera, designed to use a now expensive type of film. Once the camera is cleaned up, only a few modifications are needed to adapt it to the cyanotype method, one of which involves placing a magnet on the shutter to keep it open for the longer exposure times needed for this type of photography. There is some development to do on these pictures, but it’s relatively simple to do in comparison to more traditional chemical film development.

For anyone looking for a different way of taking photographs, or even those looking for a method of taking analog pictures without the hassle of developing film or creating a darkroom, cyanotype offers a much easier entry point and plenty of artists creating images with this method don’t use a camera at all. There are plenty of other photographic chemistries to explore as well; one of our favorites uses platinum to create striking black-and-white photos.

The State Of High Speed Rail, And A Look To Tomorrow

August 3, 2023 by 73 Comments

In the 21st century, the global transportation landscape is in shift. Politicians, engineers, and planners all want to move more people, more quickly, more cleanly. Amid the frenzy of innovative harebrained ideas, high-speed rail travel has surged to the forefront. It’s a quiet achiever, and a reliable solution for efficient, sustainable, and swift intercity and intercountry transit.

From the thriving economies of Europe and Asia to the burgeoning markets of the Middle East and America, high-speed rail networks are being planned, expanded, and upgraded whichever way you look. A combination of traditional and magnetic levitation (maglev) trains are being utilized, reaching speeds that were once the stuff of science fiction. As we set our sights towards the future, it’s worth taking a snapshot of the current state of high-speed rail, a field where technology, engineering brilliance, and visions of a greener tomorrow converge.

Continue reading “The State Of High Speed Rail, And A Look To Tomorrow” →

Better 3D Prints, Courtesy Of A Simple Mass-Produced Bracket

August 3, 2023 by 34 Comments

On the “hack/not-a-hack” scale, a 3D printed bracket for aluminum extrusions is — well, a little boring. Such connectors are nothing you couldn’t buy, and even if you insisted on printing them instead, Printables and Thingiverse are full of ready-to-use designs. So why would you waste your precious time and effort rolling your own?

According to production 3D printing company [Slant 3D], a lot of times, we forget to take advantage of the special capabilities of 3D printing. The design progression of the L-bracket shown is a perfect example; it starts as a simple L, moves on to a more elaborate gusseted design, and eventually into a sturdy sold block design that would be difficult to make with injection molding thanks to shrinkage but is no problem for a 3D printer. Taking that a step further, the bracket morphs into a socketed design, taking advantage of what 3D printers can do by coming up with a part that reduces assembly time and fastener count while making a more finished, professional look.

Again, this isn’t really about the bracket. Rather, it’s about a different way of thinking about your designs and leveraging the unique capabilities of 3D printers relative to other mass-production methods, like injection molding. We’ve covered some of [Slant 3D]’s high-volume design insights before, such as including living hinges and alternatives of pins and holes for assembling printed parts. Continue reading “Better 3D Prints, Courtesy Of A Simple Mass-Produced Bracket” →

DisplayPort: Taming The Altmode

August 3, 2023 by 7 Comments

The DisplayPort altmode is semi-proprietary, but it can absolutely be picked apart if we try. Last time, we found a cool appnote describing the DisplayPort altmode in detail, switched the FUSB302 into packet sniffing mode and got packet captures, learned about PD VDMs (vendor-defined messages), and successfully replayed the captured messages to switch a USB-C port into the DisplayPort altmode. Today, we will go through the seven messages that summon the DisplayPort altmode, implement them, and tie them all into a library – then, figure out the hardware we need to have DisplayPort work in the wild.

For a start, as you might have seen from the diagram, a single command can be either a request or a response. For instance, if you get a Discover Identity REQ (request), you reply to it with a Discover Identity ACK (response), adding your identity data to your response along the way. With some commands, the DP source will add some data for you to use; for most commands, your DP sink will have to provide information instead – and we’ll do just that, armed with the PDF provided and the packet captures.

We have seven commands we need to handle in order to get DisplayPort out of a compatible USB-C port – if you need a refresher on these commands, page 13 of the ST’s PDF on the DP altmode will show you the message sequence. These commands are: Discover Identity, Discover SVIDs, Discover Modes, Enter Mode, DP Status Update, DP Configure, and Attention. Out of these, the first four are already partially described in the base USB PD standard, the two DP commands afterwards are DisplayPort-altmode-specific but sufficiently described in the PDF we have, and the Attention command is from the base standard as well, mostly helpful for reporting state of the HPD pin. Let’s start with the first two! Continue reading “DisplayPort: Taming The Altmode” →

Let’s Listen To A Tape — Paper Tape

August 3, 2023 by 9 Comments

These days, data is as likely as not to be “in the cloud.” Otherwise, it’s probably on a USB flash drive or SD card. But in the old days, paper tape was a widespread way to store and retrieve data. A common way to start the day at the office was to toggle in a few dozen bytes of bootloader code, thread a bigger bootloader tape into your TeleType paper tape reader, and then get your coffee while the more capable bootloader clunked its way into memory. Then you could finish your brew while loading the tape with your compiler or whatever you wanted. [Scott Baker] has a Heathkit H8 and decided using a paper tape machine with it and some of his other gear would be fun.

Instead of a TeleType, [Scott] picked up a used paper tape machine from FANUC intended for the CNC industry. They are widely available on the surplus market, although a working machine might run you $500. [Scott] paid $200, so he had some work to do to make the unit operational.

Paper tape had a few varieties. For computer work, you usually had a tape that could hold eight holes across, one for each bit in a byte. However, there are also 6-bit and 5-bit tapes for special purposes or different encodings (old TeleTypes used 5-bit characters in Baudot). The paper choice varied too. You could get plain paper, oiled paper, which maybe didn’t jam as often, and Mylar, which is less likely to shred up when it does jam.

To make things even more difficult, the machines all worked a little differently as well. Sure, punches almost all use solenoids. But the tape transport was sometimes a pinch roller and sometimes a sprocket-style drive. Reading the holes could be done with mechanical contacts or optically. Some punches left little “hanging chads” on the tape, so you didn’t have to empty a confetti box to throw away the chad.

The repair job was interesting. Inside the machine is an 8051 microcontroller. There was no clock, and the circuit used two custom modules. One was simply a crystal, and the other was an oscillator. Removing both allowed a modern can oscillator to replace both modules. The next problem was a fried serial output driver. Replacing that got things working except for random resets due to a faulty brown-out reset circuit. That was easy to fix, too.

Of course, if you are really cheap, it is easy to make a paper tape reader from 8 phototransistors, and pulling tape through by hand isn’t unheard of. It can even talk USB. We’ve even seen a conference badge that can read tapes.

Continue reading “Let’s Listen To A Tape — Paper Tape” →

Get MOST Into Your Pi

August 3, 2023 by 15 Comments

When looking the modify a passenger vehicle, the Controller Area Network (CAN) bus is a pretty easy target. In modern vehicles it has access to most of the on-board systems — everything from the climate control to the instrument cluster and often even the throttle, braking, and steering systems. With as versatile as the CAN bus is, though, it’s not the right tool for every job. There’s also the Media Oriented Systems Transport (MOST) bus which is increasingly found in automotive systems to handle multimedia such as streaming music to the stereo. To access that system you’ll need to approach it slightly differently as [Rhys] demonstrates.

[Rhys] has been working on replacing the dated head unit in his Jaguar, and began by investigating the CAN bus. He got almost everything working with replacement hardware except the stereo, which is where the MOST bus comes into play. It provides a much higher bandwidth than the CAN bus can accommodate but with almost no documentation it was difficult to interact with at first. With the help of a Raspberry Pi and a lot of testing he is able to get the stereo working again with a much more modern-looking touchscreen for control. It is also able to do things like change CDs in the car’s CD player, gather song information from the CD to display on the panel, and can perform other functions of the infotainment center.

For more detailed information on the MOST bus, [Rhys] also maintains a website where he puts his discoveries and other information he finds about this system. Unfortunately car stereo systems in modern vehicles can get pretty complicated these days, but adapting car stereos in older vehicles to modern technology carries some interesting challenges as well.

Continue reading “Get MOST Into Your Pi” →

Kalman Filters Without The Math

August 2, 2023 by 25 Comments

If you program using values that represent anything in the real world, you have probably at least heard of the Kalman filter. The filter allows you to take multiple value estimates and process them into a better estimate. For example, if you have a robot that has an idea of where it is via GPS, dead reckoning, and an optical system, Kalman filter can help you better estimate your true position even though all of those sources have some error or noise. As you might expect, a lot of math is involved, but [Pravesh] has an excellent intuitive treatment based around code that even has a collaborative Jupyter notebook for you to follow along.

We have always had an easier time following code than math, so we applaud these kinds of posts. Even if you want to dig into the math, having basic intuition about what the math means first makes it so much more approachable.

Continue reading “Kalman Filters Without The Math” →