Otis Boykin’s Precision Passives Propelled The Pacemaker

September 16, 2020 by 11 Comments

The simplest ideas can be the ones that change the world. For Otis Boykin, it was a new way to make wirewound precision resistors. Just like that, he altered the course of electronics with his ideas about what a resistor could be. Now his inventions are in everything from household appliances and electronics to missile guidance computers.

While we like to geek out about developments in resistor tech, Otis’ most widely notable contribution to electronics is the control unit he designed for pacemakers, which regulate a person’s heartbeat. Pacemakers are a real-time clock for humans, and he made them more precise than ever.

Street Smarts and Book Smarts

Otis Frank Boykin was born August 29th, 1920 in Dallas, Texas to Sarah and Walter Boykin. Otis’ father was a carpenter who later became a preacher. His mother Sarah was a maid, and she died of heart failure when Otis was only a year old.

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A Walking Robot With A Single Servo

September 16, 2020 by 13 Comments

We’ve all been there — you see somebody do something cool on YouTube and you just have to give it a go. For [lonesoulsurfer], the drop-everything-and-build happened to be a little four-legged walker robot that runs on a single servo. Though it may be simple, there really is nothing like seeing a robot you created take its first steps.

[lonesoulsurfer]’s walker is made mostly from scrap aluminium and other scavenged parts like coat hangers, paper clips and the metal bits and bobs from banana jacks. The Dremeled and bent body would likely be the hardest to imitate for a first-time builder, but any sturdy chassis that allows for things screwed and bolted to it should work. Also, don’t expect it to work right away. It will take a bit of tuning to get the gait right, but it’s all part of the fun. So is modifying a 180° servo for continuous rotation.

We really like the way this robot walks — it saunters around like a long bulldog and looks like it can handle almost any terrain. Watch it walk after the break, and stick around for the build video.

There’s just something about simple robots without microcontrollers. If you’ve never heard of BEAM robots, cut your teeth on this ‘bot with circular legs.

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Decoding The Netflix Announcement: Explaining Optimized Shot-Based Encoding For 4K

September 16, 2020 by 33 Comments

Netflix has recently announced that they now stream optimized shot-based encoding content for 4K. When I read that news title I though to myself: “Well, that’s great! Sounds good but… what exactly does that mean? And what’s shot-based encoding anyway?”

These questions were basically how I ended up in the rabbit hole of the permanent encoding optimization history, in an effort to thoroughly dissect the above sentences and properly understand it, so I can share it with you. Before I get into it, lets take a trip down memory lane. Continue reading “Decoding The Netflix Announcement: Explaining Optimized Shot-Based Encoding For 4K” →

Improving More Leaf Design Flaws

September 16, 2020 by 19 Comments

[Daniel] was recently featured here for his work in improving the default charging mode for the Nissan Leaf electric vehicle when using the emergency/trickle charger included with the car. His work made it possible to reduce the amount of incoming power from the car, if the charging plug looked like it might not be able to handle the full 1.2 kW -3 kW that these cars draw when charging. Thanks to that work, he was able to create another upgrade for these entry-level EVs, this time addressing a major Leaf design flaw that is known as Rapidgate.

The problem that these cars have is that they still have passive thermal management for their batteries, unlike most of their competitors now. This was fine in the early ’10s when this car was one of the first all-electric cars to market, but now its design age is catching up with it. On long trips at highway speed with many rapid charges in a row the batteries can overheat easily. When this happens, the car’s charging controller will not allow the car to rapid charge any more and severely limits the charge rate even at the rapid charging stations. [Daniel] was able to tweak the charging software in order to limit the rapid charging by default, reducing it from 45 kW to 35 kW and saving a significant amount of heat during charging than is otherwise possible.

While we’d like to see Nissan actually address the design issues with their car designs while making these straighforward software changes (or at least giving Leaf owners the options that improve charging experiences) we are at least happy that there are now other electric vehicles in the market that have at least addressed the battery thermal management issues that are common with all EVs. If you do own a Leaf though, be sure to check out [Daniel]’s original project related to charging these cars.

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Rapid Charging Supercapacitors

September 16, 2020 by 40 Comments

Battery technology is the talk of the town right now, as it’s the main bottleneck holding up progress on many facets of renewable energy. There are other technologies available for energy storage, though, and while they might seem like drop-in replacements for batteries they can have some peculiar behaviors. Supercapacitors, for example, have a completely different set of requirements for charging compared to batteries, and behave in peculiar ways compared to batteries.

This project from [sciencedude1990] shows off some of the quirks of supercapacitors by showing one method of rapidly charging one. One of the most critical differences between batteries and supercapacitors is that supercapacitors’ charge state can be easily related to voltage, and they will discharge effectively all the way to zero volts without damage. This behavior has to be accounted for in the charging circuit. The charging circuit here uses an ATtiny13A and a MP18021 half-bridge gate driver to charge the capacitor, and also is programmed in a way that allows for three steps for charging the capacitor. This helps mitigate the its peculiar behavior compared to a battery, and also allows the 450 farad capacitor to charge from 0.7V to 2.8V in about three minutes.

If you haven’t used a supercapacitor like this in place of a lithium battery, it’s definitely worth trying out in some situations. Capacitors tolerate temperature extremes better than batteries, and provided you have good DC regulation can often provide power more reliably than batteries in some situations. You can also combine supercapacitors with batteries to get the benefits of both types of energy storage devices.

LED Art Reveals Itself In Very Slow Motion

September 15, 2020 by 9 Comments

Every bit of film or video you’ve ever seen is a mind trick, an optical illusion of continuous movement based on flashing 24 to 30 slightly different images into your eyes every second. The wetware between your ears can’t deal with all that information individually, so it convinces itself that you’re seeing smooth motion.

But what if you slow down time: dial things back to one frame every 100 seconds, or every 1,000? That’s the idea behind this slow-motion LED art display called, appropriately enough, “Continuum.” It’s the work of [Louis Beaudoin] and it was inspired by the original very-slow-motion movie player and the recent update we featured. But while those players featured e-paper displays for photorealistic images, “Continuum” takes a lower-resolution approach. The display is comprised of four nine HUB75 32×32 RGB LED displays, each with a 5-mm pitch. The resulting 96×96 pixel display fits nicely within an Ikea RIBBA picture frame.

The display is driven by a Teensy 4 and [Louis]’ custom-designed SmartLED Shield that plugs directly into the HUB75s. The rear of the frame is rimmed with APA102 LED strips for an Ambilight-style effect, and the front of the display has a frosted acrylic diffuser. It’s configured to show animated GIFs at anything from 1 frame per second its original framerate to 1,000 seconds per frame times slower, the latter resulting in an image that looks static unless you revisit it sometime later. [Louis] takes full advantage of the Teensy’s processing power to smoothly transition between each pair of frames, and the whole effect is quite wonderful. The video below captures it as best it can, but we imagine this is something best seen in person.

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Whimsical Solder Stand Moonlights As Toy 3D Printer

September 15, 2020 by 12 Comments
A few Lego pieces provide key functionality, like an articulated dispenser head.

Most of us have bent a length of solder into a more convenient shape and angle when soldering, and just sort of pushed the soldering iron and work piece into the hanging solder instead of breaking out a third hand. Well, [yukseltemiz] seems to have decided that a solder dispenser and a miniature 3D printer model can have a lot in common, and created a 1/5 scale Ender 3 printer model that acts as a solder stand and dispenser. The solder spool hangs where the filament roll would go, and the solder itself is dispensed through the “print head”.

It’s cute, and we do like the way that [yukseltemiz] incorporated a few Lego pieces into the build. A swivel and eyelet guides the solder off the roll and a small Lego ball and socket gives the dispenser its articulation, an important feature for bending solder to a more convenient angle for working. It makes us think that using Lego pieces right alongside more traditional hardware like M3 nuts and bolts might be an under-explored technique. You can see the unit in action in the brief assembly video, embedded below.

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