Mysterious Files PH

You may not know what a ADM-3, a TV910, or a H1420 are, but you probably have at least heard of a VT-100. They are all terminals from around the same time, but the DEC VT-100 is the terminal that practically everything today at least somewhat emulates. Even though a real VT-100 is rare, since it defined what have become ANSI escape sequences, most computers you’ve used in the last few decades speak some variation of the VT-100’s language. [Nikhil] wanted to see if you could use a VT-100 for real work today.

While the VT-100 wasn’t a general-purpose computer, it did have an 8080 inside. It only had about 3K of RAM, which was enough to act as a serial terminal. A USB serial port and a terminal with modern Linux, how hard could it be?

As it turns out there were a few issues. MacOS assumes terminals can take data at 9600 baud with no handshaking, apparently. It also means that any application that assumes redrawing the whole terminal is fast will be sorry for that choice.

Of course, there are commands modern VT-100-like terminals accept that the original didn’t. However, as you’ll see in the post, all of these things you can either live with or solve.

It is easy to make your own VT-100 replica. While the VT-100 may seem simple today, it was a marvel compared to even older terminals.

This week Jonathan chats with Andrei, Mahir, and Praneeth, live on location at Texas Instruments! The team at TI has been working hard to provide really good Open Source support for Sitara processors, including upstreaming support to the mainline Linux kernel. We talk about the CI pipeline for these devices, the challenges of doing Open Source at a big company, and more. Check it out!

• https://github.com/texasinstruments
• https://www.beagleboard.org/
• https://www.ti.com/design-development/software-design/open-source.html

Did you know you can watch the live recording of the show right on our YouTube Channel? Have someone you’d like us to interview? Let us know, or have the guest contact us! Take a look at the schedule here.

Direct Download in DRM-free MP3.

If you’d rather read along, here’s the transcript for this week’s episode.

Theme music: “Newer Wave” Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

For the average rider, inner tubes have been one of the most enduring and unchanging parts of bicycle design over the decades. They’re made of rubber, they have a Schrader or Presta valve, and they generally do an okay job at cushioning the ride.

However, if you’re an above-average rider, or just obsessive about your gear, you might consider butyl rubber tubes rather old hat. Today, there are far fancier—and more expensive—options on the market if you’re looking to squeeze every drip of performance out of your bike.

A Series Of Tubes

Butyl rubber inner tubes have a lot of things going for them, which is why they’ve been the standard forever. Rubber holds air well, and is easy enough to repair in the event of a puncture. It’s also cheap. However, there are some ways in which the butyl inner tube holds a bicycle back. A thick rubber tube isn’t exactly light; even in a road bicycle application, a single tube can weigh 100 grams or more. They also add to the rolling resistance of a wheel and tire combination. In these regards, other materials have the potential to offer greater performance.

Latex

Latex is a material with many familiar uses, but it’s also recently become a popular alternative material for making inner tubes. It has the benefit of being very light, with a typical road bike latex tube saving 50 grams or more compared to the butyl rubber equivalent. The more flexible material also reduces rolling resistance by several watts at higher speeds, something which can make a real difference under competitive racing conditions. In a more qualitative sense, many riders also prefer the feel of riding on lighter latex tubes.

However, latex tubes also come with drawbacks. The ultra-thin, lightweight material can be susceptive to sudden failure from excessive heat, which can risk a crash in the worst cases. For this reason, the lightest latex tubes are often recommended for use on disc brake bikes only, due to the high temperatures that can be generated by rim brakes on a long descent. Latex tubes also lose air relatively quickly, and thus it’s recommended to pump up latex tubes to the required pressure ahead of every ride. They’re also difficult, but not impossible, to patch, and require some care to avoid damaging their thin walls during installation.

TPU

You might be familiar with thermoplastic polyurethane (TPU) for its use as a flexible 3D printing filament. As it turns out, it’s also a viable material for producing bicycle inner tubes. TPU tubes shave off weight and rolling resistance compared to butyl rubber, albeit not quite as much as the finest latex tubes out there. They do, however, hold air a lot better than latex, reducing the need to reset tyre pressure before each ride. Ride quality is also generally considered better than rolling on traditional butyl rubber tubes. TPU tubes also fold up incredibly small—a largely meaningless benefit in use, but really helpful if you’re trying to pack a spare or three to take on a ride.

Unfortunately, TPU tubes can be quite expensive to procure—often double the price of latex and three or four times that of a butyl rubber tube. The thinnest versions can similarly be at risk of heat failures when used with rim brakes, so it’s important to check before installation if your TPU tubes are rated for use with disc brakes only. Puncture repair can also be difficult, though there are some specialist patches on the market if you wish to attempt it.

Roll, Roll, Roll

It’s worth noting that there is another way to go, as well. It’s possible to buy wheel and tire setups that eliminate inner tubes entirely. These “tubeless” systems offer a major weight reduction, and tend to have lower rolling resistance than even the lightest, most flexible tube setups out there. They’re not really a development of tube technology, but moreso a divergence in wheel and tyre design. In any case, they are pricy, and can require some special equipment to install and maintain. To allow them to self-heal in the event of minor punctures, they’re also typically filled with sealant. In the event of more serious damage, it’s often still possible to install a tube to keep riding, but this is an incredibly messy process that will get sealant all over you.

If you’re a regular commuter cyclist, butyl rubber tubes will probably remain your go-to choice. They’re the cheapest to buy, the easiest to repair, and any benefits from lighter, more efficient tubes are largely wasted on a commute. However, if you’re an avid road cyclist looking for the best feel and efficiency, or especially if you’re getting serious about racing, then you really ought to consider leaving butyl behind for something better. Happy cycling!

If you want to dabble in audio digital signal processing, you would probably think of grabbing a dedicated DSP chip. But thanks to [WeebLabs], you could just pick up a Pi Pico and use this full-featured DSP library.

The system supports plug-and-play USB audio interface that enumerates on Windows, Linux, macOS, and iOS. It can handle 16- or 24-bit inputs at up to 96 kHz. You can output up to four channels of 24-bit S/PDIF or I2S, or switch to an RP2350 to get eight channels. This lets you drive a DAC easily. There is also a direct output for a subwoofer that doesn’t require a DAC.

Each channel has a pre-amp, and a matrix mixer allows routing with different gains and phases for each input. An equalizer allows ten bands per channel. There are also modules to do volume leveling, loudness compensation, and headphone cross-feed.

The library uses both cores of the CPU and manages up to ten preset configurations. The Pico does get an overclock and uses a fixed-point representation. The Pico 2 (RP2350) doesn’t need overclocking and uses single-precision floating point.

Overall, this looks like a great base for any sort of soundcard-like project. We’ve seen DSP stunts on the Pico before. This might also make a nice base for other audio projects.

Australia’s payphones are an iconic part of the national landscape, even if they’re not as important as they once used to be. However, they’re having a resurgence of late, in part thanks to a new national pastime—the sport of Payphone Tag!

Created by [Alex Allchin], the game is simple. To play, you first sign up on the website and get your emoji and 5-digit PIN. You then go out and find a payphone, dial the Payphone Tag number, and enter your PIN when prompted. This lets you “capture” the phone, raising your score in the game. If a phone is already captured, no matter—just head out there, dial the number, and key in your own PIN to steal it. You can also push your score even higher by capturing three payphones in a triangle on the map to get bonus points.

It’s a fun geospatial game that’s also free to play, because Telstra made payphone calls free back in 2022. It might cost you a bit to get out to some phones, but there are plenty you can reach with the aid of free public transport at the moment, anyway. Protip—at the time of writing, there are a ton of easy captures to be had on Kangaroo Island. It might just cost you a pretty penny to get out there. Have at it!

We’d love to see some stats from Telstra as to whether this is making a dent in overall payphone usage rates. In any case, there were 800 players in the last 7 days and a full 36,640 captures so far, so a lot is happening out there. We fully expect to see this concept spread to other nations in turn, though it might be less attractive in places where you still need to dig out a coin to make a call.

We’ve featured a few payphone hacks over the years. If you’re doing something rad with these telecommunication devices of yesteryear, we’d love to hear about it on the tipsline.

With all the battery technologies and modern low-current sleep modes in most microcontrollers, running a sensor and microcontroller combo off-grid and far away from any infrastructure is usually not too difficult a task. Often these sorts of systems can go years without maintenance or interaction. But for something that still has to be off-grid but needs to do some amount of work every now and then like actuating a solenoid or quickly turning a servo, these battery-based systems can quickly run out of juice. To solve that problem, [Nelectra] has come up with this high-power capacitor-based IoT system.

Although supercapacitors don’t tend to have the energy density of batteries, they’re perfectly capable of powering short tasks in off-grid situations like this. They’re also typically able to tolerate lower voltages, extreme temperatures, and shock better than most batteries as well. A small solar cell on the top of this device keeps it topped up, and when running in deep sleep mode can hold a charge for up to six days. In more real-world applications supporting sensors, relays, or other actuators, [Nelectra] has found that it can hold a charge for around three days. When a quick burst of power is needed, it can deliver 1.5 A at 9 V or 500 mA at 24 V.

[Nelectra]’s stated goal for this build is to bridge low-power energy harvesting and practical field actuation, enabling maintenance-free systems such as irrigation control and remote switching without batteries, going beyond simple sensor applications while not relying on always-on power from somewhere else. Something like this would work really well in applications like this automated farm, which has already provided some unique solutions to intermittent power and microcontroller applications that need very high reliability.

If you don’t already have your tickets to Hackaday Europe, pick them up now. The clock is ticking! Today, we’d like to announce our keynote speaker, the remainder of our featured talks, and two more workshops. (And if you want workshop tickets, which always go fast, get those soon!)

Hackaday Europe is super excited to welcome back Hackaday Superfriend [Sprite_tm] to kick off the event with a keynote talk on how he made a retrogaming PC from bare silicon. Don’t miss it.