speed

38 Articles

Street-Legalize Your Ebike With A Magnet

March 1, 2021 by 98 Comments

Getting into e-biking is a great hobby. It can get people on bikes who might otherwise not be physically able to ride, it can speed up commute times, and it can even make hauling lots of stuff possible and easy, not to mention it’s also fun and rewarding. That being said, there are a wide array of conflicting laws around what your e-bike can and can’t do on the road and if you don’t want to run afoul of the rules you may need a programmable device that ensures your e-bike is restricted in the appropriate way.

This build is specifically for Bafang mid drives, which can be up to 1000 W and easily power a bike beyond the speed limit where [Tomblarom] lives. A small microcontroller is housed in a waterproof box on the bike and wired between the motor’s display and controller. A small hall effect sensor and magnet sit by this microcontroller, and if the magnet is removed then the microcontroller reprograms the bike’s controller to limit the speed and also to disable the throttle, another feature that is illegal in some jurisdictions but not others. As an added bonus, the microcontroller also handles brake lights, turn signals, and automatic headlights for the bike as well.

While the project page mentions removing the magnet while getting pulled over to avoid fines and other punishments, that’s on you. We imagine this could still be useful for someone who wants to comply with local laws when riding on the road, but still wants to remove the restrictions when riding on private property or off-road where the wattage and speed restrictions might not apply.

Watch A Fast Sand Plotter Plow Patterns At Speed

September 22, 2020 by 21 Comments

[Mark]’s sand table wisely has a glass top.
Most of us have probably seen a video of a sand drawing table at work, in which a steel ball — magnetically-coupled to a gantry under a layer of sand — lazily draws geometric patterns with utter precision and zen-like calmness. That’s all well and good, but [Mark Rehorst] thinks it can also be interesting to crank up the speed and watch the ball plow through sand just as physics intended. There’s a deeper reason [Mark] is working at this, however. Faster drawing leads to less crisp results, but by how much, exactly? To answer this, [Mark] simply ran his table (which is named The Spice Must Flow) at both fast and slow speeds and documented the results.

These two images show the difference between running the table at 100 mm/s versus 500 mm/s. The slower speed is noticeably crisper, but on the other hand the faster speed completed the pattern in about a fifth of the time. [Mark] says that as the ball aggressively accelerates to reach target speeds, more sand is thrown around over existing lines, which leads to a loss of detail.

Crisper detail, or a faster draw? Which is “better” depends on many things, but it’s pretty clear that [Mark]’s cat finds the fast version more exciting. You can see [Mark]’s table at high speed and the cat’s reaction in the video, embedded below.

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Enforce Speed Limits With A Rusty Bike

June 15, 2019 by 37 Comments

They say you can’t manage what you can’t measure, and that certainly held true in the case of this bicycle that was used to measure the speed of cars in one Belgian neighborhood. If we understand the translation from Dutch correctly, the police were not enforcing the speed limit despite complaints. As a solution, the local citizenry built a bicycle with a radar gun that collected data which was then used to convince the police to enforce the speed limit on this road.

The bike isn’t the functional part of this build, as it doesn’t seem to have been intended to move. Rather, it was chosen because it is inconspicuous (read: rusty and not valuable) and simply housed the radar unit and electronics in a rear luggage case. The radar was specially calibrated to have less than 1% error, and ran on a deep cycle lead acid battery for around eight days. Fitting it with an Arduino-compatible shield and running some software (provided on the github page) is enough to get it up and running.

This is an impressive feat of citizen activism to provide the local police with accurate data to change a problem in a neighborhood. Not only was the technology put to good use, but the social engineering involved with hiding expensive electronics in plain sight with a rusty bicycle is a step beyond what we might have thought of as well.

Thanks to [Jo_elektro] for the tip!

GPS Overlays Give Real Life Racing A Video Game Feel

September 4, 2018 by 14 Comments

Racing is certainly exciting for the person rocketing around the track fast enough to get the speedometer into the triple digits, and tends to be a decent thrill for the spectators if they’ve got good seats. But if you’re just watching raw race videos on YouTube from the comfort of your office chair it can be a bit difficult to appreciate. There’s a lack of context for the viewer, and it can be hard to get the same sense of speed and position that you’d have if you saw the event first hand.

In an effort to give his father’s racing videos a bit more punch, [DusteD] came up with a clever way of adding video game style overlays to the recordings. The system provides real-time speed, lap times, and even a miniature representation of the track complete with a marker to show where the action is taking place. The end result is that recordings of Dad’s exploits on the track could pass as gameplay footage from Gran Turismo (we know GT doesn’t have motorcycles, but you get the idea).

The first part of the system is the tracker itself, which consists of a GPS receiver, an Arduino Pro Micro, and an SD card module. [DusteD] powers the device with two 18650 cells in parallel, and a DC-DC boost converter to step it up to 5V. Everything is contained in a 3D printed enclosure that he designed in OpenSCAD, with the only external elements being a toggle switch, a momentary switch, and most critically, a set of LEDs.

These LEDs play into the second part of the system, the software. The blinking LEDs are positioned so they’ll get picked up by the camera, which is then used to help synchronize the data stored on the SD card with the video. [DusteD] came up with some software that will take the speed and position information from the card, and turn it into PNG files with transparent backgrounds. These are then placed on top of the video with the help of FFmpeg. It takes a little adjustment to get everything lined up properly, but as the video after the break shows the end result is very impressive.

This build reminds us of the Raspberry Pi powered GPS helmet camera we featured a few years back, and it’s interesting to see how the two projects achieved what’s essentially the same goal in different ways.

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Electric Bike From The Ground Up

August 8, 2018 by 21 Comments

Electric vehicles are getting more traction these days, but this trend is rolling towards us in more ways than just passenger vehicles. More and more bikes are being electrified too, since the cost of batteries has come down and people realize that they can get around town easily without having to pay the exorbitant price to own, fuel, and maintain a car. Of course there are turnkey ebikes, but those don’t interest us much around here. This ebike from [Andy] is a master class in how to build your own ebike.

Due to some health issues, [Andy] needed a little bit of assistance from an electric motor on his bike, but found out that the one he wanted wouldn’t fit his current bike quite right. He bought a frame from eBay with the right dimensions and assembled the bike from scratch. Not only that, but when it was time to put the battery together he sourced individual 18650 cells and built a custom battery for the bike. His build goes into great detail on how to do all of these things, so even if you need a lithium battery for another project this build might be worth a read.

If you’ve never been on an electric bike before, they’re a lot of fun to ride. They’re also extremely economical, and a good project too if you’re looking for an excuse to go buy a kit and get to work. You can get creative with the drivetrain too if you’d like to do something out of the box, such as this bike that was powered by AA batteries and a supercapacitor.

Hands On With Python 3.7: What’s New In The Latest Release

July 23, 2018 by 42 Comments

Used for general purpose programming, data science, website backends, GUIs, and pretty much everything else; the first programming language for many, and claimed to be the fastest growing in the world, is of course Python. The newest version 3.7.0 has just recently been released.
Naturally any release of Python, no matter how small, undergoes meticulous planning and design before any development is started at all. In fact, you can read the PEP (Python Enhancement Proposal) for Python 3.7, which was created back in 2016.

What’s new in 3.7? Why should you upgrade? Is there anything new that’s actually useful? I’ll answer these questions for you by walking through some examples of the new features. Whilst there’s not much in this release that will make a difference to the Python beginner, there’s plenty of small changes for seasoned coders and a few headline features you’ll want to know about.

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Car Revival According To Tesla

March 28, 2018 by 44 Comments

Frankencars are built from the parts of several cars to make one usable vehicle. [Jim Belosic] has crossed the (finish) line with his Teslonda. In the most basic sense, it is the body of a Honda Accord on top of the drive train of a Tesla Model S. The 1981 Honda was the make and model of his first car, but it wasn’t getting driven. Rather than sell it, he decided to give it a new life with electricity, just like Victor Frankenstein.

In accord with Frankenstein’s monster, this car has unbelievable strength. [Jim] estimates the horsepower increases by a factor of ten over the gas engine. The California-emissions original generates between forty and fifty horsepower while his best guess places the horsepower over five-hundred. At this point, the Honda body is just holding on for dear life. Once all the safety items, like seatbelts, are installed, the driver and passengers will be holding on for the same reason.

This kind of build excites us because it takes something old, and something modern, and marries the two to make something in a class of its own. And we hate to see usable parts sitting idle.

Without a body, this electric car scoots around with its driver all day, and this Honda doesn’t even need the driver inside.

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