Author: Al Williams

4599 Articles

Inside A Hisense TV Repair Attempt

April 6, 2024 by 18 Comments

Many of us misspent our youth fixing televisions. But fixing a 1970s TV is a lot different than today — the parts were big and tubes were made to be replaced. Have you torn into a big flat screen lately? It is a different world, as [The Fixologist] shows us in the video below.

The TV in question was rescued from a neighbor who was about to throw it away. If you are like us, you’ll watch the first few minutes and see it powers up, but the screen is very dark. Back light problem, right? No problem. But it turned out to be more than we thought.

Honestly, we assumed it might be the power supply, and we would have put a power supply on the LED leads to test that first. That would have been smart because taking the panel off to reveal the LEDs was very difficult! There were two bad LEDs, though, so in the end you’d have had to do it anyway.

We were disappointed that after fixing the LED, he cracked the LCD panel during the reinstallation. So, in the end, this was more of a teardown video and not a repair video. He seemed to think a lot of the tape in the unit was to thwart repairs. That could be, but we wondered if it made manufacturing the TV easier which, after all, is mostly what they care about.

This isn’t the first time we’ve heard people tearing into a TV and wondering if the factory was against them. We’ve considered it, but we are pretty sure it isn’t the case.

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DIY 6 GHZ Pulse Compression Radar

April 6, 2024 by 10 Comments

Conceptually, radar is pretty simple: send out a radio wave and time how long it takes to get back via an echo. However, in practice, there are a number of trade-offs to consider. For example, producing a long pulse has more energy and range, but limits how close you can see and also the system’s ability to resolve objects that are close to each other. Pulse compression uses a long transmission that varies in frequency. Reflected waves can be reconstituted to act more like a short pulse since there is information about the exact timing of the reflected energy. [Henrik] didn’t want to make things too easy, so he decided to build a pulse compression radar that operates at 6 GHz.

In all fairness, [Henrik] is no neophyte when it comes to radar. He’s made several more traditional devices using a continuous wave architecture. However, this type of radar is only found in a few restricted applications due to its inherent limitations. The new system can operate in a continuous wave mode, but can also code pulses using arbitrary waveforms.

Some design choices were made to save money. For example, the transmitter and receiver have limited filtering. In addition, the receiver isn’t a superheterodyne but more of a direct conversion receiver. The signal processing is made much easier by using a Zynq FPGA with a dual-core ARM CPU onboard. These were expensive from normal sources but could be had from online Chinese vendors for about $17. The system could boot Linux, although that’s future work, according to [Henrik].

At 6 GHz, everything is harder. Routing the PCB for DDR3 RAM is also tricky, but you can read how it was done in the original post. To say we were impressed with the work would be an understatement. We bet you will be too.

Radar has come a long way since World War II and is in more places than you might guess. We hate to admit it, but we’d be more likely to buy a ready-made radar module if we needed it.

IRC Client On Bare Metal

April 6, 2024 by 14 Comments

In the beginning, there was the BIOS, and it was good. A PC’s BIOS knows how to set up the different hardware devices, grab a fixed part of a hard drive, load it, and run it. That’s all you need. While it might be all you need, it isn’t everything people want, so a consortium developed UEFI, which can do all the things a normal BIOS can’t. Among other things, UEFI can load code for the operating system over the network instead of from the hard drive.

In true hacker fashion, [Phillip Tennen] thought, “Does it have to be an operating system?” The answer, of course, is no. It could be an IRC client. He chose Rust to implement everything. While UEFI does provide a network stack, it isn’t very easy to use, apparently. It also provides support for a mouse. [Phillip] ported his GUI toolkit library over, and then the rest is just building an IRC client.

The client isn’t the easiest to use because, after all, this is a lark. Why would you want to do this? On the other hand, we can think of reasons we might want to take control of a UEFI motherboard and use it for something. If you want to do that, this project is a great template to jump-start your endeavors.

We’ve looked at the UEFI system a few times. Or, you can use it to play DOOM.

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Linear Feedback Shift Registers For FPGAs

April 6, 2024 by 28 Comments

If you want to start an argument at a Hackaday meeting, you have only to ask something like “How much does this weigh?” or “What time is it?” But if you really want to start a street brawl, you can always say, “Are these numbers random?” Making random numbers that are actually random is actually a tough nut to crack. Most of what we do is, technically, pseudo-random (but we’ll say random number and assume you know what we mean). One way to generate seemingly random sequences is to use a linear feedback shift register or LFSR. You can use LFSRs in software, but they are also very useful in hardware design and [Adam Taylor] takes us through his use of them on FPGAs in a recent post. Continue reading “Linear Feedback Shift Registers For FPGAs” →

ColecoVision Cart Rises From Ashes

April 5, 2024 by 8 Comments

We felt bad for [Mark] of Mark Fixes Stuff. Apparently, his house burned down and took virtually everything, including his retrocomputer collection. He did manage to pull out a few things from the remains including a ColecoVision cartridge that was — honestly — melted. We probably would have written it off, but [Mark] was determined to recover something.

He was fortunate that the PCB was not burned, but it was covered in soot and possibly other things. However, the case looked like a chocolate bar left on a dashboard for a few summer days in the tropics.

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3D Printer Hot Off The Griddle

April 5, 2024 by 9 Comments

If you look at [Proper Printing’s] latest video — see below — you’ll immediately get the idea behind his latest printer. There are two heads on two separate gantries, which, of course, opens up many possibilities. But when you think you’ve seen enough, you find out the heated bed is a kitchen griddle, and… well, for us, we had to keep watching.

The heated bed idea was interesting, although the flatness left something to be desired. While it is a simple idea, getting the two gantries to move reliably across the hotbed griddle took a lot of parts and a careful design. We wonder how evenly the griddle heats — ours definitely has hot spots when we cook with it.

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Fictional Computers: The Three Body Problem

April 5, 2024 by 54 Comments

If you intend to see the Netflix series “The Three Body Problem” or you want to read the Hugo-winning story from Chinese author [Cixin Liu], then you should probably bookmark this post and stop reading immediately. There will be some mild spoilers. You have been warned.

While the show does have some moments that will make your science brain cringe, there is one scene that shows a computer that could actually be built. Would it be practical? Probably not in real life, but in the context provided by the show, it was perfectly feasible. It could have, however, been done a little better, but the idea was — like many great ideas — both deceptively simple and amazingly profound. The computer was made of human beings. I’m not talking like Dune’s mentats — humans with super brains augmented by drugs or technology. This is something very different.

Background

This is your last chance. There are spoilers ahead, although I’ll try to leave out as much as I can. In the story, top scientists receive a mysterious headset that allows them to experience totally immersive holodeck-style virtual reality. When they put the headset on, they are in what appears to be a game. The game puts you in a historical location — the court of Henry VIII or Ghengis Kahn. However, this Earth has three suns. The planet is sometimes in a nicely habitable zone and sometimes is not. The periods when the planet is uninhabitable might have everything bursting into flames or freezing, or there might not be sufficient gravity to hold them on the planet’s surface. (Although I’ll admit, I found that one hard to grasp.)

Apparently, the inhabitants of this quasi-Earth can hibernate through the “chaotic eras” and wait for the next “stable era” that lasts a long time. The problem, as you probably know, is that there is no general closed-form solution for the three-body problem. Of course, there are approximations and special cases, but it isn’t easy to make long-term predictions about the state of three bodies, even with modern computers.

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