An RGB laser projector opened up on a workbench

Laser Projector Needs Hardware Hack After Software Mod

December 11, 2022 by Robin Kearey 13 Comments

You probably recognize that dreadful feeling when you reboot a gadget after updating its firmware, only to be greeted by a blank screen and an unresponsive device. This apparently happened to the previous owner of a bricked RGB laser projector that [Buy It Fix It] got his hands on: it briefly flashed its laser on power-up but otherwise remained completely dead.

A thorough inspection of the major components didn’t reveal any physical damage, so the issue had to be in software. [Buy It Fix It] managed to connect his Segger J-link programmer to the STM32 main processor and downloaded the contents of its firmware, only to find the remains of a PDF file which seemed to have been accidentally flashed into the chip’s program space. Fixing the device should then just be a matter of restoring the proper firmware, but [Buy It Fix It] wasn’t able to find a copy of it anywhere.

What he did find was Maximus64’s GitHub repository that contained a software mod for a different projector model, as well as its original firmware. Flashing that version didn’t fix [Buy It Fix It]’s projector either, although it did now start to actuate its galvos.

A bit of reverse engineering revealed that the two projectors were very similar from a hardware point of view, but had their laser drivers hooked up to different I/O pins: simply cutting the board traces and soldering some wires to re-route the signals was enough to bring the projector back into a working state.

Having to modify hardware in order to make it fit a piece of software is unfortunate, but sometimes you just have to make do with what you’ve got. If you’ve got no firmware to begin with, then you might even have to write your own from scratch.

Continue reading “Laser Projector Needs Hardware Hack After Software Mod” →

See What You’re In For When Buying And Moving A Lathe

December 11, 2022 by Donald Papp 46 Comments

Sometimes, with patience and luck, one can score a sweet deal on machinery. But for tools that weigh many hundreds of pounds? Buying it is only the beginning of the story. [Ben Katz] recently got a lathe and shared a peek at what was involved in moving a small (but still roughly 800 pound) Clausing 4901 lathe into its new home and getting it operational.

The lathe had sat unused in a basement, but was ready for a new home.

Moving such a stout piece of equipment cannot simply be done by recruiting a few friends and remembering to lift with the legs. This kind of machinery cannot be moved and handled except with the help of other machines, so [Ben] and friends used an engine hoist with a heavy-duty dolly to get it out of the basement it was in, and into the bed of a pickup truck. Separating the lathe from its base helped, as did the fact that the basement had a ground-level egress door which meant no stairs needed to be involved.

One also has to consider the machine’s ultimate destination, because not all floors or locations can handle nearly a thousand pounds of lathe sitting on them. In [Ben]’s case, that also meant avoiding a section of floor with a maintenance trapdoor when moving the lathe into the house. Scouting and knowing these things ahead of time can be the difference between celebratory pizza and deep dish disaster. Pre-move preparation also includes ensuring everything can physically fit through the necessary doorways ahead of time; a task that, if ignored, will eventually explain itself.

With that all sorted out, [Ben] dives into cleaning things up, doing function checks, and in general getting the lathe up and running. He provides some fantastic photos and details of this process, including shots of the 70s-era documentation and part diagrams.

Watch the first chips fly in the short video embedded below. And should you be looking at getting a lathe of your own? Check out our very own buyer’s guide to lathe options.

Continue reading “See What You’re In For When Buying And Moving A Lathe” →

A Straightforward Old-Fashioned DAC

December 11, 2022 by Jenny List 32 Comments

With modern microcontrollers, the process of interfacing with the analogue world is easy. Simply enable the on-board DAC or ADC, and talk to the world. If you’ve ever done this with a slightly older microprocessor, you might have encountered the DAC and ADC as chips in their own right, but how about the earliest generation of microprocessors? In those days, if an analogue component was needed, the circuit which would later be integrated on chip would have to be made from scratch. So it is that [Florian Wilhelm Dirnberger] has built a very old-style 6-bit DAC, using a circuit that would have been familiar back in the early 1970s.

At its heart are a pair of 4007 triple CMOS inverters, which form the six bits driving a resistor ladder DAC. This is simply a chair of R… 2R resistors, relying on Ohm’s law for its operation. Each successive bit contributes twice the current to the output of its predecessor, and the 4007 simply provides a buffered supply for the bits.

It’s the simplest of DACs, if not the most capable. Back in the day a typical ADC might also use this circuit, feeding a comparator alongside the input voltage. The microprocessor would count through the digital values until the comparator output bit flipped, at which point it would take the counter value as the analogue measure. You may never need to build one when your microcontroller has one built in, but it’s useful to know how simple DACs and ADCs work.

If the subject interests you, we’ve had a look at DACs including resistor ladders used in audio.

Fixing (And Improving!) An Annoying Apartment Entry System

December 11, 2022 by Donald Papp 7 Comments

[Zak]’s two-floor apartment has a typical door entry control system, but the setup is less than ideally convenient. The wall-mounted telephone-like intercom is downstairs, but [Zak] is usually upstairs. What’s an enterprising hacker to do? Obviously the most elegant solution is to simply do without visitors in the first place, but [Zak] opted for a more full-featured solution to the problem.

The layout of the typical wall-mounted door intercom is less than ideal.

He fixed things with a custom ESP8285-based board that, with the help of opto-isolation, allows him to detect visitors and grant entry without having to be physically present at the wall-mounted intercom. It’s even integrated into Telegram, and has a few neat new features. Let’s take a look.

The first interesting bit is how [Zak] rolled his own opto-isolation. The door entry system uses 14 VAC and is frankly — electromagnetically-speaking — a very noisy device. Attaching GPIO pins directly to this system from the ESP board for interfacing is not an option. The solution in situations like this is to use opto-isolation, so that interfaced devices can be electrically isolated from one another.

Rather than use off-the-shelf options, [Zak] opted to keep things small and economical by rolling his own solution using side-mounted IR LEDs on the small interface PCB. LEDs can also act as photodiodes, so by pointing two LEDs directly at one another and driving one LED from the door control system and measuring the small amount of resulting current on the other LED, [Zak] can detect states without having to directly connect a GPIO pin.

Continue reading “Fixing (And Improving!) An Annoying Apartment Entry System” →

A VM In An AI

December 10, 2022 by Jenny List 41 Comments

AI knoweth everything, and as each new model breaks upon the world, it attracts a new crowd of experimenters. The new hotness is ChatGPT, and [Jonas Degrave] has turned his attention to it. By asking it to act as a Linux terminal, he discovered that he could gain access to a complete Linux virtual machine within the model’s synthetic imagination.

The AI’s first response was a prompt, so he of course first tried to list the files. Up came a list of directories, so the next step was to create a file and put some text in it. All of this resulted in a readable file, so there was some promise in this unexpected computing resource. But can it run code? Continue reading “A VM In An AI” →

Gaze Upon The Swimming Mechanical Stingray, Made With LEGO

December 10, 2022 by Donald Papp 5 Comments

Stingrays have an elegant, undulating swimming motion that can be hypnotic. [Vimal Patel] re-created this harmony with his fantastic mechanical mechanical stingray using LEGO pieces and a LEGO Technics Power Functions motor. The motor is set in a clever arrangement that drives the motion remotely, so that it and electrical elements can stay dry.

The mechanical stingray sits at the end of a sort of rigid umbilical shaft. This shaft connects the moving parts to the electrical elements, which float safely on the surface. This leaves only the stingray itself with its complex linkages free to move in the water, while everything else stays above the waterline.

We’ve seen some impressive LEGO creations before, like this race car simulator and pneumatic engine, and the mechanical action in this stingray is no exception. Interested in making your own? The part list and build directions are available online, and you can see it in action in the video embedded below.

Continue reading “Gaze Upon The Swimming Mechanical Stingray, Made With LEGO” →

An alarm clock with a Nixie tube display

Retro Alarm Clock With Nixies Is Thoroughly Modern Inside

December 10, 2022 by Robin Kearey 12 Comments

We feature a lot of clocks here at Hackaday, but alarm clocks seem to be less popular for some reason. Maybe that’s because no-one enjoys being woken up in the morning, or simply because everyone uses their smartphone for that purpose already. In any case, we’re delighted to bring you [Manuel Tosone]’s beautiful Nixie tube alarm clock that cleverly combines modern and classic technologies in a single package.

The clock and alarm functionalities are implemented by a PIC24 microcontroller on a custom mainboard. It keeps track of time through its real-time clock with battery backup, and plays a song from an SD card when it’s time to wake up. A 2 x 3 W class D audio amplifier plus a pair of stereo speakers should be able to wake even the heaviest sleepers.

Of course, the real party piece is the clock’s display: four IN-4 Nixie tubes show the time, with neon tubes indicating the day of the week. The 180 V needed for the Nixies is generated by an MC34063A-based boost converter, which also powers the neon tubes.

Instead of using the standard current-limiting resistor for each Nixie tube, [Manuel] designed an array of transistor-based current sources: this enables linear control of the tubes’ brightness, and should keep the amount of light constant even as the tubes age. The individual segments are switched by SN75468 Darlington arrays, with no need for those hard-to-find SN74141 drivers.

The mainboard and the display are housed inside a 3D-printed case that mimics the style of 1980s digital alarm clocks, but with a nice 1970s twist courtesy of those Nixie tubes. [Manuel]’s GitHub page has all the schematics as well as extensive documentation describing the circuit’s operation — an excellent resource if you’re planning to build a Nixie project yourself. If Nixies aren’t your thing, you can also make an alarm clock with a VFD tube, or even roll your own luminous analog dial.

Continue reading “Retro Alarm Clock With Nixies Is Thoroughly Modern Inside” →