Mysterious Files PH

After previously putting a very basic version of Minecraft on the Game Boy Color, [Tobi] decided to have some fun and port that version also to the Super Nintendo (SNES), just to see what would happen with its more powerful hardware. Even without using an add-on chip like the Super FX 3D chip that made games like Star Fox and Doom possible with its 3D-rendered geometry, the basic SNES hardware can already provide a serviceable Minecraft experience.

You can download the SFC file here, featuring a starting world in which you can do all the usual Minecraft-ing shenanigans, like world destruction and construction. Unsurprisingly the game’s resolution is much higher than on the GBC, though the brief glimpse [Tobi] shows of Minecraft on the Game Boy Advance (GBA) with its proper 3D-rendering hardware are leaps ahead of what the basic SNES can do.

This of course raises the question of what Minecraft on the SNES could look like once you add the Super FX or similar 3D accelerator chips for the SNES into the mix. Rather than just being limited to sprite-based graphics and transformations, suddenly you can use real polygons.

Impressive as it most certainly is when an amateur fabricates a semiconductor, most of the projects we’ve seen are more demonstrations than workable chips. [Dr. Semiconductor], however, is going much further with his fabrication process, and is already working on a method to bond chips to printed circuit boards. It’s difficult to align a PCB with the pads on the underside of an opaque silicon wafer, however, so as a trial run he’s made and bonded some transparent LED chips.

The starting material for these chips is a gallium nitride (GaN) LED epiwafer, a stacked structure of n-doped GaN, an indium gallium nitride quantum well layer, and p-doped GaN grown on a sapphire substrate. When current passes through the structure, electrons from the n-doped layer and holes from the p-type layer recombine in the quantum well layer, emitting blue light. To make a functional LED from this, [Dr. Semiconductor] needed to make electrical contacts to both the n-type and p-type layers. Making the n-type contact required cutting through the p-type and quantum well layers.

This would normally be done with reactive ion etching in chlorine, but [Dr. Semiconductor] came up with a new process: a 355-nm ultraviolet etching laser causes GaN to break down into gallium and nitrogen, with the resulting cut being cleaned up by a potassium hydroxide etch. To deposit the contacts themselves, [Dr. Semiconductor] formed a photoresist mask, deposited metal (nickel, silver, and titanium) in a sputtering chamber, and used a developer solution to dissolve the mask and lift off the unwanted metal regions.

When [Dr. Semiconductor] applied current between the two contacts, the LED glowed bright blue. The next step was to mount it to a PCB; to do so, he first sliced the wafer into individual LED chips with the ultraviolet laser. He then electroplated indium bumps onto a printed circuit board, positioned the chip above these bumps, added some rosin flux, and melted the indium bumps. This soldered the chip to the board and let the board power the LED.

Like most commercial LEDs, these were blue; most LED assemblies additionally include a phosphor layer which absorbs blue light and emits another color. To create a white LED, for example, [Dr. Semiconductor] mixed cerium-doped yttrium aluminium garnet phosphor power with clear silicone and spread it over the LED. This absorbs some of the blue light and emits yellow light, and the resulting mixture of blue and yellow light looks white to human eyes.

We’ve previously covered some of the history of LEDs and the phosphors which make them useful. This seems to be the first inorganic LED we’ve seen, but we’ve also seen a few homemade OLEDs.

Thanks to [SpuriousIndices] for the tip!

Over recent years there have been a range of classic 16-bit consoles coaxed into running familiar operating systems, with -nommu Linux being a favourite. But the 16-bit era had its own operating systems of note, and [1d4r3k] has brought one of them to a console that fit very much into a different 16-bit camp. It’s Atari’s TOS, on a Sega Mega CD.

We should in all fairness start by saying it’s not “real” TOS, but EmuTOS, an open-source drop-in replacement. So far it supports a serial keyboard device, a printer, and sound, and it mounts the CD or cartridge it booted from, a RAMdisk, internal backup RAM, and cartridge save RAM. We’re told in the tip email that there’s also been some work porting GEOS to the platform, and thus the GEOS software suite may be ported to it.

Sadly there are no images, so we can’t see it working, but trying it looks to be as straightforward as burning aan ISO or flashing a cartridge if you have the original hardware. We have no idea as to whether it would be any use given the specs of the Sega, but given that TOS ran on Ataris without a lot of RAM we suspect it might be. Meanwhile, here’s a Megadrive/Genesis running Linux.

Header: 軍事用懐中電灯, CC BY-SA 4.0.

Drone control links are, from a radio signals perspective, nothing short of amazing: using a transmitter capable of transmitting, at most, one watt, a protocol such as ExpressLRS (ELRS) can control a drone over 100 kilometers away. [Stan], who has been building a drone electronics stack from scratch, recently designed four ELRS receivers and went over the principles behind their incredible range.

Up to a certain point, the simplest way to increase a radio’s range is to lower the frequency; lower radio frequencies penetrate better through most materials and don’t attenuate as quickly with distance. However, although ELRS can use 900 MHz bands, [Stan]’s receivers primarily use 2.4 GHz. The major improvement is in modulation: unlike other control protocols, which mostly use frequency modulation, or Wi-Fi, which uses phase and amplitude modulation, ELRS uses Chirp Spread Spectrum modulation. This has a low data rate, but it’s very reliable; every bit is transmitted as a chirp – a linearly rising radio tone – and the data is encoded in the chirp’s starting frequency. To decode this, the receiver multiplies it with an inverse chirp, then takes a fast Fourier transform, revealing the starting frequency. This process has an equivalent gain of 24 dB, which is enough to let it decode signals even below the receiver’s noise floor.

The hardware [Stan] designed to implement this was comparatively simple, just an ESP32 microcontroller, an SX1281 radio chip, and a few peripherals. All four receivers worked in 2.4 GHz, but two had additional 900 MHz antennas. Against RF design convention, one of the receivers used a via to connect the antenna. This would normally cause a significant impedance mismatch, but since there were enough ground-plane vias nearby, the current return path was barely affected; the receiver’s performance hardly changed. In one test, all four receivers maintained a connection at more than five kilometers, despite a forest blocking the signal’s path.

We previously covered ExpressLRS when it was still an emerging technology. To get this kind of range, it builds on LoRa technology, which has reached some impressive distance records.

Thanks to [Keith Olson] for the tip!

Making a film camera is a project within the reach of almost anyone, from the experimenter with cardboard and sticky tape, to the machinist with an aluminium billet. But 3D printing has opened up the world of cameras to whole new set of experimenters, and we’ve seen some very impressive builds here as a result. For all that, there’s always been a particularly tricky aspect to a home made camera: the shutter. In particular, making one with variable speed has proved almost impossible. Now [Camera Things] has given it a very good shot, with a sliding 3D printed design.

To cock it, both the strips are pulled across, before the blind strip is pushed back, and the shutter operates by sliding back under the influence of a rubber band. The clever part in this case is that the blind strip can be partially pushed back to affect the size of the shutter opening. The effect is then of a variable width strip of light passing over the film, which is equivalent to varying the speed of a conventional shutter.

Due to space constraints he’s only able to make it a half frame shutter, so he’s abandoning this design in favour of a more complicated set of vertical leaves. Sadly he’s not made the files available, but we thing proficient CAD users should be able to make their own version. The video is below the break.

It’s not the first printable shutter we’ve seen, but it remains the first variable one.

If you’ve got a cheap ham rig, it might not be very practical for you to receive certain transmissions out of the box. However, if you were to hack in a convenient little beat frequency oscillator (BFO) to your rig, then you’d be up and running. Here’s a simple way to do just that with a venerable old part everybody knows and loves.

The build in question concerns the use of a 555 timer IC. It’s seasoned with the right smattering of resistors and capacitors to taste, producing a 455 kHz beat frequency oscillator. This can be injected into the intermediate frequency chain of a receiver, making up for the lack of a steady carrier wave when receiving continuous-wave and single side-band suppressed carrier transmissions. Thanks to a potentiometer in the circuit, it’s tunable, too, from 455 kHz, plus or minus twenty percent or so. Thanks to the versatility of the 555, it’s possible to run the chip on a wide voltage range, anywhere from 4.5 volts to 16 volts, which makes it easy to install in just about any old radio set without requiring adding a specialized power supply. There’s also an alternative design that EDN covered in greater detail some time ago.

If you’re eager to dive into a wider range of transmissions than your radio can currently receive, this old-school ham hack could be just what the shack ordered. We feature plenty of good ham hacks around these parts, and don’t forget—we always want to hear about the freshest ones on the tipsline.

Would you like to make your own energy? Why, who doesn’t in this era of rising costs! A sterling engine always looks like a good fit for that: highly efficient, with no risk of a boiler explosion. A thermoacoustic sterling engine looks even better, since it has only one moving part at the output end. A thermoacoustic sterling engine you can 3D print yourself looks best of all, and that’s what [my engines] has on offer, now that even the burner and hot end of his thermoacoustic engine are designed for SLA metal printing.

We previously reported on the open-source engine, but there’ve been some improvements worth talking about. For one thing, he’s integrated a biogas/methane burner directly inside the 3D-printable hotend. For another, that 3D-printed design allows for an excellent heat exchange geometry that would be very hard to get any other way. The whole thing is open source with plans available at OwnEnergy.org, where you can find links to the apparently-mandatory Discord channel and now an old-style forum to actually collaborate on the design, which is open-source. The site is also now the home of all data and discussion about [my engines]’s homescale biogas plant, which is the power source for this little engine.

If you’d rather print a combustion engine, you can do that, too, but you’ll need more “vitamins” than this unit requires.