Giant Spinning POV Christmas Tree

Spinning Holographic POV Christmas Tree Of Death

December 27, 2022 by 11 Comments

[Sean Hodgins] really harnessed the holiday spirit to create his very own Giant Spinning Holographic Christmas Tree (of Death). It’s a three-dimensional persistence-of-vision (POV) masterpiece, but as a collection of rapidly spinning metal elements, it’s potentially quite dangerous as well. As [Sean] demonstrates, the system can display other images and animations well beyond the realm of mere holiday trees.

Initial experiments focused on refining the mechanical structure, bearings, and motor. A 1/2 horsepower A.C. motor was selected and then the dimensions of the tree were “trimmed” to optimize a triangular frame that could be rotated at the necessary POV speed by the beefy motor.  A six-wire electrical slip ring allows power and control signaling to be coupled to the tree through its spinning central shaft.

The RGB elements are SK9888 LEDs also know as DotStar LEDs. DotStar LEDs are series-chainable, individually-addressable RGB LEDs similar to NeoPixels. However, with around 50 times the pulse width modulation (PWM) rate, DotStars are more suitable for POV applications than NeoPixels.  The LED chain is driven by a Raspberry Pi 4 single board computer using a clever system for storing image frames.

If deadly rotational velocity is not your cup of tea, consider this slower spinning RGB Christmas tree featuring a DIY slip ring. Or for more POV, may we suggest this minimalist persistence-of-vision display requiring only a few LEDs and an ATtiny CPU.

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The Spit-Detecting USB Flash Drive Is Nearly Here

December 25, 2022 by 17 Comments

Regular readers may recall that security researcher and general open source hardware fanatic [Walker] has been planning a rather unusual flash drive for some time — one that will only show its contents if the user makes sure to lick their fingers before plugging it in. We’re pleased to report that theory has recently given way to real hardware, and the Ovrdrive “self-destructing” flash drive is now a step closer to reality.

The last time we checked in with [Walker], he hadn’t yet put any hardware together, though he was fairly sure what components he would need and how it would all go together. This was assisted somewhat by the fact that USB flash drives are such a ubiquitous piece of tech, making their principle parts plentiful and fairly well documented. As explained in the video below, all you really need to spin up your own flash drive is the USB connector, the controller chip, and a nice slab of flash memory for it to access. Though naturally you’re on your own for spit detection.

The build video has some gorgeous camera work.

What we especially like about this project is that [Walker] is releasing the whole thing as open source hardware. So even if you’re not interested in the whole lick-for-access feature, you’ve still got a boilerplate flash drive design to build on. We haven’t seen a lot of DIY projects tackle USB Mass Storage previously, and perhaps this design can change that.

But of course, only if the thing works. According to the video after the break, [Walker] seems to have hit a snag with this revision of the hardware. While it enumerates as a storage device when plugged into the computer, the operating system claims its capacity is zero. He thinks there might be a swapped trace between the controller and flash chip to blame, so hopefully he can get things sorted out before too long. We’ve been covering this project since the summer, and are eager to see it cross the finish line.

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It’s Ethernet, From An SPI Interface

December 19, 2022 by 37 Comments

Over the years as microcontrollers have become fast enough to do the heavy lifting, we have become used to 10 megabit Ethernet being bit-banged from interfaces it was never meant to emerge from. We think however that we’ve never seen one driven from an SPI interface, so this one from [Ivan] may be a first. With a cleverly designed transceiver using logic chips, it even offers a chance to understand something about the timing of an Ethernet interface, too.

The differential logic signals derived from a simple Ethernet transceiver can be read by an SPI bus, but for the lack of a clock line. The challenge was then to construct a circuit the would construct the required clock pulses from the state changes on the data line. This would become a monostable with XOR gate, and a shift register to handle the clock during the preamble phase.

The resulting circuitry fits neatly on a shield for the ST Nucleo 64 board, where while it might not be the obvious choice for an Ethernet shield it certainly does the job.

If unexpected Ethernet is your thing, how about the i2s peripheral on an ESP8266?

Mazda Patents Spinning Dorito To Extend EV Range

December 16, 2022 by 44 Comments

OK, so a Wankel engine doesn’t really use a Dorito as its cylinders, but it sure looks like one. The company has announced it will offer a range extender rotary engine for the MX-30 electric “crossover” vehicle, but [CarBuzz] dug into the patent papers to find out that it has some interesting twists.

The MX-30 is an EV with a relatively small 35.5 kWh battery. Like a hybrid vehicle, the car includes a small internal combustion engine that can charge the battery. It does not, however, directly drive the wheels at any time. The Wankel has several improvements, including a secondary port that allows more air into the combustion chamber when the engine has to produce high power. But there’s a problem…

The secondary port is great when you are pushing hard, but at low speed, it produces inefficiency. To combat that, Mazda includes a valve to seal off the second port when it doesn’t make sense to open it. But that’s not the strange part. The strange part is that the engine also has its own electric assist motor that runs off the main battery.  That’s right. The battery you are charging provides some energy to operate the electric assist motor to help the engine that is charging the battery. If that makes your head spin like the Wankel’s rotor, you aren’t alone.

The assist motor can assist or retard the output shaft during the intake stroke. This can optimize the intake to the combustion chamber. Of course, this will cause odd movement in the engine’s output, but since it doesn’t drive the car, who cares? The battery isn’t going to mind if the output isn’t smooth.

The Wankel shows up in a lot of odd places. We’ve seen Wankel air compressors. Despite detractors, there have been many improvements in the design over the years.

Two-Thirds Keyboard Is Inspired By The Typesetting Era

December 16, 2022 by 18 Comments

We see all kinds of custom keyboard builds around here. Most of them are intended to optimize typing to the user’s desires. This glorious build from [Attoparsec] isn’t one of those, and is instead part of the growing joke keyboard genre. The so-called Two-Thirds Keyboard is inspired by the long-gone typesetting era.

The build is based on the typecases used in the era when type was assembled by hand. Typesetters would grab “majuscule” letters from the upper case of type, and “miniscule” letters from the lower case of type, when setting a page, which would go on to influence how we refer to those letters today. Letters that came up more often, like e and s, would get larger compartments in the type cases, while rarer letters like z and q would get smaller compartments. The Two-Thirds keyboard replicates this by giving the most common letters the biggest keys, while rarer letters and upper-case majuscule letters get smaller keys. The overall layout matches that of the popular Two-Thirds California Case of type that grew popular in the US in the typesetting era.

There were some engineering issues in building the keyboard. While stabilizers are available for wide keys like Enter and Space in regular keyboard designs, stabilizing keys that are wide and high is fussy. The build relies on multiple switches to enable them to move cleanly. Nor were 2×2 and 2×3-sized custom keycaps readily available. In the end, resin printing was key to producing all the necessary components.

Typing on the keyboard is not quick, but lower speeds were probably acceptable in the typesetting era. Regardless, [Attoparsec] used it for a full week to do it justice, going from around 10  wpm to 22 wpm by the end of the test.

It’s a fun build, but by no means the slowest keyboard we’ve ever seen.

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An art deco style computer made of several grey/blue boxes with silver grates on top of a maple platform.

Clean Slate Is A Vintage Amplifier-Inspired PC

December 9, 2022 by 9 Comments

Hacks that bring a vintage flair to modern electronics never get old, and [Jeffrey Stephenson] delivers with his Project Clean Slate inspired by vintage tube amps.

Thinking outside the traditional single box PC, [Jeffrey] built his computer into a series of component-specific boxes all attached to a platform housing the Micro ATX motherboard. The base is made of plywood with a birds-eye maple veneer and each of the component boxes features two different sizes of wire mesh to manipulate the viewer’s perception of the dimensions. Even the I/O and graphics card plates are custom made from aluminum for this build.

If you really want to dig into how this PC came to life, there’s a very detailed build log including every step of the process from bare board to finished product. We love when we get an inside look at the thought process behind each design decision in a build.

We’ve featured [Jeffrey] before with his Humidor Cluster, and you may also like this PC inside a vintage radio.

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Nixie Display Module Is Addressable Via SPI

December 3, 2022 by 5 Comments

There are plenty of SPI interface screens on the market, but few of them have the charm of the good old Nixie tube. [Tony] decided to whip up a simple three-Nixie module that could be addressed via SPI. 

The stacked construction keeps things compact.

The module relies on a PIC16F15344 microcontroller to run the show, using its built-in SPI interface. It’s built with four stacked-up PCBs for ease of assembly and testing. It uses an internal buck converter to create the 170 volts required for the Nixie tubes from a 6 to 12 volt input. The high-voltage lines are routed towards the inside of the stack to minimize any nasty shocks when handling, though caution would still be advisable.

Driving the display is as simple as sending 16-bit words over the SPI interface, with the device operating in SPI client mode 1. If you’re looking for a simple way to have projects write output to a nice Nixie display, this module could be just what you’re looking for. Alternatively, if you can’t lay your hands on the tubes, there are other pretty solutions out there, too. Video after the break.

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