A Cold Gas Thruster On An RC Car

August 15, 2021 by Lewin Day 12 Comments

Tesla have boldly claimed that one day they’ll ship a Roadster complete with a cold-gas thruster for truly ridiculous acceleration. Whether or not that ever comes to pass remains to be seen, but [Engineering After Hours] decided to try out the technology on an RC car instead.

The thruster uses a pair of disposable CO2 canisters to deliver 1770 g of thrust via a converging-diverging nozzle. Actuated by servos and a simple valve, the system dumps the high-pressure CO2 to help accelerate the car up to speed. Paired with sticky tires and a powerful brushless motor, the plan was to try and beat Tesla’s claimed 1.1 second 0-60mph acceleration figure for the thruster-boosted roadster.

Unfortunately, the high center of gravity of the RC car led to stability issues, largely due to the mounting of the thruster itself. Additionally, the high weight of the car – around 4.3kg – meant that at best, the thruster would only add 0.5g to the vehicle’s acceleration.

While the car didn’t net a quick 0-60 time, it’s still neat to see a cold gas thruster on an RC car. It may not have been a Tesla-beater like some earlier projects, but it was cool all the same. Video after the break.

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Nintendo Zapper Reborn As Home Automation Remote

August 7, 2021 by Brian McEvoy 3 Comments

Generally, using a gun to turn your lights off is dangerous and expensive, but for the [DuctTape Mechanic], it’s just how he does things. Video also after the break. To be fair, he uses a salvaged Nintendo Zapper, not a firearm, and replaces the guts with an RF transmitter. We are shocked that he chose a radio model instead of infrared seeing as how he is repurposing a light gun, but our scores in Duck Hunt suggest he made the right choice.

The transmitter comes from a keychain remote, so it all fits neatly inside the Zapper chassis. A couple of wires hijack the stock button and run to the stock trigger, so you keep that authentic feel. The receiver side is a bit trickier. When it senses a button press, it sends a pulse, as you would find in a garage door opener, but to keep a lamp on, there needs to be some latching and so there is an Arduino. The microcontroller keeps a tally and operates a 10 amp relay module, so it is mostly acting as the glue between hardware. All of the mains electrical components sit in a blue plastic box with a receptacle on the front.

We don’t see the Zappers used for their intended purposes much anymore because they rely on old technology, but that doesn’t keep people from repurposing the iconic peripheral.

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Foam F-35 Learns To Hover

July 15, 2021 by Tom Nardi 2 Comments

With cheap RC hardware, powerful motors, and high-capacity battery packs, getting something to fly has never been easier. It also helps that, whether you’re into fixed-wing craft or multirotors, there’s plenty of information and prior art floating around online that you can use to jumpstart your own build. But when it comes to homebrew vertical take-off and landing (VTOL) planes, things are a bit trickier.

Luckily for us, [Nicholas Rehm] has made all the plans and information necessary to duplicate his incredible RC F-35 available for anyone who wants to experiment with these relatively niche fliers. Even if it was a standard park flier, the build would be worth a close look thanks to the vectored thrust motors that give it phenomenal maneuverability and a top speed in the neighboorhood of 120 KPH (80 MPH). But with the flick of a switch, the plane transitions into a tricopter-like flight mode that allows it to land and takeoff vertically.

How does it work? The downward facing motor just behind the “cockpit” lifts up the front of the foam flier and tilts left and right to provide yaw control, while the two motors on the back tilt down to lift up the rear of the aircraft. Aviation buffs in the audience may recognize this as being fairly close to how the actual F-35B hovers, although on the real jet fighter, downward thrust under the wings is generated by redirected turbine exhaust rather than dedicated motors, and yaw control is provided by swiveling the engine’s nozzle rather than the front lift fan.

Getting the plane to takeoff vertically was one thing, but being able to transition from a hover into forward flight was quite another. To make this aerial transformation possible [Nicholas] actually had to write his own flight controller software, which he calls dRehmFlight. The GPLv3 code runs on the Teensy 4.0 and uses the common GY-521 MPU6050 gyroscope/accelerometer, so you don’t need to get any custom boards spun up just to give it a test ~~drive~~ flight. In the video below he walks through configuring the software for VTOL operation by defining how each control surface and motor is to respond to control input given the currently selected flight mode.

It probably won’t surprise you to hear that this isn’t the first time [Nicholas] has experimented with unusual flying machines. Last year we covered his RC Starship, which managed to stick the “belly flop” landing even before SpaceX managed to get the real life version down in one piece.

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Teardown: VTech Smart Start

July 12, 2021 by Tom Nardi 12 Comments

Regular readers may be aware that I have a certain affinity for vintage VTech educational toys, especially ones that attempted to visually or even functionally tie in with contemporary computer design. In the late 1980s, when it became obvious the personal computer was here to stay, these devices were seen as an affordable way to give kids and even young teens hands-on time with something that at least somewhat resembled the far more expensive machines their parents were using.

A perfect example is the PreComputer 1000, released in 1988. Featuring a full QWERTY keyboard and the ability to run BASIC programs, it truly blurred the line between toy and computer. In fact from a technical standpoint it wasn’t far removed from early desktop computers, as it was powered by the same Zilog Z80 CPU found in the TRS-80 Model I.

By comparison, the Smart Start has more in common with a desktop electronic calculator. Even though it was released just two years prior to the PreComputer 1000, you can tell at a glance that it’s a far more simplistic device. That’s due at least in part to the fact that it was aimed at a younger audience, but surely the rapid advancement of computer technology at the time also played a part. Somewhat ironically, VTech did still at least attempt to make the Smart Start look like a desktop computer, complete with the faux disk drive on the front panel.

Of course, looks can be deceiving. While the Smart Start looks decidedly juvenile on the outside, that doesn’t mean there aren’t a few surprising technical discoveries lurking under its beige plastic exterior. There’s only one way to find out.

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Auto-Aiming Nerf Gun To Give You The Edge In Battle

June 3, 2021 by Danie Conradie 13 Comments

Ever wished for some robotic enhancements for your next nerf war? Well, it’s time to dig through the parts bin and build yourself a nerf gun with aimbot built right in, courtesy of [3Dprintedlife]. (Video, embedded below.)

The gun started with a design borrowed from [Captain Slug]’s awesome catalog of open source nerf guns. [3Dprintedlife] modified the design to include a two-axis gimbal between the lower and the upper, driven by a pair of stepper motors via an Arduino. For auto-aim, a camera module attached to a Raspberry Pi running OpenCV was added. When the user half-pressed the trigger, OpenCV will start tracking whatever was at the center of the frame and actively adjust the gimbal to keep the gun aimed at the object until the user fires. The trigger mechanism consists of a pair of microswitches that activate a servo to release the sear. It is also capable of tracking a moving target or any face that comes into view.

We think this is a really fun project, with a lot of things that can be learned in the process. Mount it on a remote control tank and you’d be able to wage some intense battles in your backyard. All the files are available on GitHub.

You are never too old for a good old nerf battle. Whether you want to be a sniper, a machine gunner, or a heavy weapons specialist, there’s a weapon to build for every role.

Teardown: RADICA I-Racer

May 26, 2021 by Tom Nardi 3 Comments

Long before the Oculus Rift and HTC Vive came along, some of the biggest names in gaming tried to develop practical stereoscopic displays. These early attempts at virtual reality (VR) were hindered by the technical limitations of their time, and most never progressed beyond the prototype stage. Of the ones that did make it to retail shelves, none managed to stick around for very long. The best known example is Nintendo’s Virtual Boy, which ended up being a financial disaster upon its release in 1995 and some regard as the gaming giant’s greatest blunder.

Despite these public failures, Radica still felt compelled to throw their hat into the ring. Best known for their line of relatively simplistic LCD handheld games, the company produced several rudimentary stereoscopic stand-alone titles in the late 1990s to try and cash in on the VR fad. Among the later entries in this series was 1999’s NASCAR i-Racer, which at least externally, looks quite a bit like modern VR headset.

Featuring a head-mounted stereoscopic display, a handheld controller, force feedback, and integrated headphones, you’d certainly be forgiven for thinking the i-Racer was ahead of its time. But its reliance on the primitive LCD technology that put Radica on the map, combined with the need to keep the game as cheap as possible, keeps the experience planted firmly in the 1990s. But perhaps there’s something we can do about that.

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3D Printed Tank Takes On The Elements

May 16, 2021 by Lewin Day 4 Comments

Commercially available radio control tanks are fun and all, but sometimes you’ve just got to build your own. [Let’s Print] did just that, whipping up a tank on his 3D printer before taking it out in the snow.

The tank is a fairly straightforward build, relying on a pair of brushed motors for propulsion, controlled by twin speed controllers hooked up to standard radio control hardware. Everything else is bespoke, however, from the 3D printed gearboxes, to the chassis and the rather aggressive-looking tracks. The pointed teeth of the latter leave deep indentations when the tank cruises around on mud, though weren’t quite enough to stop the little tank from getting high-centered in deep snow.

The build isn’t for the impatient, however. [Let’s Print] notes that the tracks alone took over 80 hours to run off in PETG, let alone the rest of the frame and gearboxes. However, we’re sure it was a great learning experience, and great fun to drive outside. Now the next step is surely to go bigger. Video after the break.

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