2025-08-15 19:00:36
When you mention Teletext or Videotex, you probably think of the 1970s British system, the well-known system in France, or the short-lived US attempt to launch the service. Before the Internet, there were all kinds of crazy ways to deliver customized information into people’s homes. Old-fashioned? Turns out Teletext is alive and well in many parts of the world, and [text-mode] has the story of both the past and the present with a global perspective.
The whole thing grew out of the desire to send closed caption text. In 1971, Philips developed a way to do that by using the vertical blanking interval that isn’t visible on a TV. Of course, there needed to be a standard, and since standards are such a good thing, the UK developed three different ones.
The TVs of the time weren’t exactly the high-resolution devices we think of these days, so the 1976 level one allowed for regular (but Latin) characters and an alternate set of blocky graphics you could show on an expansive 40×24 palette in glorious color as long as you think seven colors is glorious. Level 1.5 added characters the rest of the world might want, and this so-called “World System Teletext” is still the basis of many systems today. It was better, but still couldn’t handle the 134 characters in Vietnamese.
Meanwhile, the French also wanted in on the action and developed Antiope, which had more capabilities. The United States would, at least partially, adopt this standard as well. In fact, the US fragmented between both systems along with a third system out of Canada until they converged on AT&T’s PLP system, renamed as North American Presentation Layer Syntax or NAPLPS. The post makes the case that NAPLPS was built on both the Canadian and French systems.
That was in 1986, and the Internet was getting ready to turn all of these developments, like $200 million Canadian system, into a roaring dumpster fire. The French even abandoned their homegrown system in favor of the World System Teletext. The post says as of 2024, at least 15 countries still maintain teletext.
So that was the West. What about behind the Iron Curtain, the Middle East, and in Asia? Well, that’s the last part of the post, and you should definitely check it out.
If you are interested in the underlying technology, teletext data lives in the vertical blanking interval between frames on an analog TV system. Data had page numbers. If you requested a page, the system would either retrieve it from a buffer or wait for it to appear in the video signal. Some systems send a page at a time, while others send bits of a page on each field. In theory, the three-digit page number can range from 100 to 0x8FF, although in practice, too many pages slow down the system, and normal users can’t key in hex numbers.
For PAL, for example, the data resides in even lines between 6 and 22, or in lines 318 to 335 for odd lines. Systems can elect to use fewer lines. A black signal is a zero, while a 66% white signal is a one, and the data is in NRZ line coding. There is a framing code to identify where the data starts. Other systems have slight variations, but the overall bit rate is around 5 to 6 Mbit/s. Character speeds are slightly slower due to error correction and other overhead.
Honestly, we thought this was all ancient history. You have to wonder which country will be the last one standing as the number of Teletext systems continues to dwindle. Of course, we still have closed captions, but with digital television, it really isn’t the same thing. Can Teletext run Doom? Apparently, yes, if you stretch your definition of success a bit.
2025-08-15 16:00:58
Lithium-titanate (LTO) is an interesting battery chemistry that is akin to Li-ion but uses Li2TiO3 nanocrystals instead of carbon for the anode. This makes LTO cells capable of much faster charging and with better stability characteristics, albeit at the cost of lower energy density. Much like LiFePO4 cells, this makes them interesting for a range of applications where the highest possible energy density isn’t the biggest concern, while providing even more stability and long-term safety.
That said, LTO is uncommon enough that finding a battery management system (BMS) can be a bit of a pain. This is where [Vlastimil Slintak]’s open source LTO BMS project may come in handy, which targets single cell (1S) configurations with the typical LTO cell voltage of around 1.7 – 2.8V, with 3 cells in parallel (1S3P). This particular BMS was designed for low-power applications like Meshtastic nodes, as explained on the accompanying blog post which also covers the entire development and final design in detail.
The BMS design features all the stuff that you’d hope is on there, like under-voltage, over-voltage and over-current protection, with an ATtiny824 MCU providing the brains. Up to 1 A of discharge and charge current is supported, for about 2.4 Watt at average cell voltage. With the triple 1,300 mAh LTO cells in the demonstrated pack you’d have over 9 Wh of capacity, with the connected hardware able to query the BMS over I2C for a range of statistics.
Thanks to [Marcel] for the tip.
2025-08-15 13:00:53
There has been a huge proliferation in AI music creation tools of late, and a corresponding uptick in the number of AI artists appearing on streaming services. Well before the modern neural network revolution, though, there was an earlier tool in this same vein. [harke] tells us all about Microsoft Music Producer 1.0, a forgotten relic from the 1990s.
The software wasn’t ever marketed openly. Instead, it was a part of Microsoft Visual InterDev, a web development package from 1997. It allowed the user to select a style, a personality, and a band to play the song, along with details like key, tempo, and the “shape” of the composition. It would then go ahead and algorithmically generate the music using MIDI instruments and in-built synthesized sounds.
As [harke] demonstrates, there are a huge amounts of genres to choose from. Pick one, and you’ll most likely find it sounds nothing like the contemporary genre it’s supposed to be recreating. The more gamey genres, though, like “Adventure” or “Chase” actually sound pretty okay. The moods are hilariously specific, too — you can have a “noble” song, or a “striving” or “serious” one. [harke] also demonstrates building a full song with the “7AM Illusion” preset, exporting the MIDI, and then adding her own instruments and vocals in a DAW to fill it out. The result is what you’d expect from a composition relying on the Microsoft GS Wavetable synth.
Microsoft might not have cornered the generative music market in the 1990s, but generative AI is making huge waves in the industry today.
2025-08-15 10:00:20
Do you calibrate your digital meters? Most of us don’t have the gear to do a proper calibration, but [Mike Wyatt] shares his simple way to calibrate his DMMs using a precision resistor coupled with a thermistor. The idea is to use a standard dual banana plug along with a 3D-printed housing to hold the simple electronics.
The calibration element is a precision resistor. But the assembly includes a 1% thermistor. In addition to the banana plugs, there are test points to access the resistor and another pair for the thermistor.
In use, you plug the device into the unit you want to test. Then you clip a different temperature sensor to the integrated thermistor. Because the thermistor is in close proximity to the meter’s input, it can tell the difference between the ambient temperature and the meter. [Mike] says the bench meters get warmer than hand-held units.
This is, of course, not a perfect setup if you are a real metrology stickler. But it can be helpful. [Mike] suggests the precision resistor be over 100 ohms since anything less really isn’t a candidate for a precision measurement with two wires. Debating over calibration? We do that, too.
2025-08-15 07:00:44
[mircemk] has been working on wireless power transmission. Using a Class-E Tesla coil with 12 turns on the primary and 8 turns on the secondary and a 12 volt input he can send a few milliwatts to power an LED over a distance of more than 40 centimeters or power a 10 watt bulb over a distance of about 10 centimeters. With the DC input set at 24 volts the apparatus can deliver 5 watts over a distance of a few centimeters and a light is still visible after separating the primary and secondary coils by more than 30 centimeters.
There are many types of Tesla coil and we can’t go into the details here but they include Spark-Gap Tesla Coils (SGTC) and Solid-State Tesla Coils (SSTC), among others. The Class-E coil demonstrated in this project is a type of SSTC which in general is more efficient than an SGTC alternative.
Please bear in mind that while it is perfectly safe to watch a YouTube video of a person demonstrating a functional Tesla coil, building your own is hazardous and probably not a good idea unless you really understand what you’re doing! Particularly high voltages can be involved and EMI/RFI emissions can violate regulations. You can damage your body with RF burns while not feeling any pain, and without even knowing that it’s happening.
If you’d like to read more about wireless power transmission it is certainly a topic we’ve covered here at Hackaday in the past, you might like to check out Wireless Power Makes For Cable-Free Desk or Transmitting Wireless Power Over Longer Distances.
2025-08-15 04:00:27
[Electronoobs] is using some brushless motors to make a DIY wind turbine. His recent video isn’t about the turbine itself, but a crucial electronic part: the three-phase rectifier. The reason it is so important is due to the use of brushless motors. Normal motors are not ideal for generating power for several reasons, as explained in the video below.
The brushless motors have three windings and generate three outputs, each out of phase with the others. You can’t just join them together because they are 120 degrees out of phase. But a special rectifier can merge the inputs efficiently and output a low-ripple DC voltage.
The rectifier will have to handle a lot of power, so it uses beefy devices with heat sinks. The design is very similar to a full-wave bridge rectifier, but instead of two legs, each with two diodes, this one has three legs. This is still not as efficient as you would like. A synchronous rectifier would be even more efficient but also more complicated.
Still, we have no doubt the board will do its job. We’re anxious to see the turbine come together. Want to build your own? Maybe start smaller. Too big? You can strip it down even further.
