E-Bikes Turned Solar Car

October 9, 2023 by Danie Conradie 20 Comments

There is something to be said for a vehicle that gains range just by standing outside in the sun. In the video after the break, [Drew Builds Stuff] demonstrates how he turned a pair of bicycles into a solar-powered vehicle.

The inspiration for this build started with a pair of 20″ steel framed fat tire bikes [Drew] picked up in a liquidation sale. He welded up a simple steel chassis, and attached the partial bicycle frame and forks to the chassis, using them as steerable front wheels. A short arm was welded to each of the fork, linking them together with threaded rods and rod ends that connect to centrally mounted handlebars. The rear driving wheels are from a 20″ e-bike conversion kit, with the disk brake assembly from the cannibalized bikes.

The solar part of this build comes in the form of three 175W flexible solar panels mounted on cedar frames, coming in at 10 lbs per mounted panel. [Drew] considered using conventional rigid solar panels, but they would have been 4-6 times heavier. The two panels mounted to the rear of the vehicle are on a hinged frame to allow easy access to the electronics below. Battery storage is made up of two 24V 100Ah batteries wired in series, connected to a 60A solar charge controller and the e-bike motor controllers.

The vehicle has a top speed of about 45km/h and 100km range on batteries alone. It might not be fast or engineered for maximum efficiency, but it looks like a ton of fun and relatively simple to build. As [Drew] says, it’s not a how-to for building a perfect solar-powered vehicle, it’s how he built one.

Continue reading “E-Bikes Turned Solar Car” →

Learning About Ferroresonant Transformers While Fixing A 1970s Power Supply

October 9, 2023 by Maya Posch 22 Comments

Ferroresonant (constant voltage) transformer diagram. Secondary side is kept in full saturation with the tank, keeping voltage constant. (Credit: Usagi Electric)

While troubleshooting the power supply of a 1970s Centurion system, [Usagi Electrics] came across a fascinating feature of these units: the ferroresonant, or constant voltage transformer (CVT). The main difference between a regular transformer and a CVT is that the former has a quite direct correlation between the input and output voltage, as the magnetic flux induced on the primary side is directly translated to the secondary (output) side.

A CVT adds a second element on the secondary side in the form of a tank circuit (LC circuit) – essentially a large capacitor – along with a magnetic shunt that ‘short circuits’ part of the magnetic flux between the primary and secondary side. The result of this is that even as the primary side is kept well below the saturation point where efficiency plummets, the secondary side is kept within this saturation region, enabling a very constant output voltage across a wide range of input voltages. For the Centurion’s power supply this input range goes from 90 to 130 VAC.

Continue reading “Learning About Ferroresonant Transformers While Fixing A 1970s Power Supply” →

The Ultimate US Astronomy Roadtrip

October 9, 2023 by Adam Zeloof 10 Comments

Have 73 hours to kill and fancy a 4,609-mile road trip? Then you can check out some of the best observatories in the US (although we would probably recommend taking a couple of weeks rather than cramming the trip into three days, so you can spend at least one night stargazing at each).

Matador Network compiled a list of what they call the top ten US observatories, and published the daunting map you see above. Even if your trip is plagued by cloudy skies, rest assured the destinations will still be worth a visit. From Arizona’s Lowell Observatory, where the evidence Edwin Hubble used to formulate the Big Bang Theory was collected, to the Green Bank National Radio Observatory in West Virginia, home of Earth’s largest fully-steerable radio telescope, each site has incredibly rich history.

All of the observatories are open to the public in some way or another, but some are only accessible a few days per month, so make sure you plan your trip carefully! You may even want to travel with your own homemade telescope, Game Boy astrphotography rig, or, if you’re really dedicated, portable radio telescope.

Continue reading “The Ultimate US Astronomy Roadtrip” →

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Arboreal Keyboards

October 9, 2023 by Kristina Panos 6 Comments

Well, unfortunately we don’t know much yet about this nice wooden keyboard from [Kelvin Chow], but maybe this inclusion will encourage [Kelvin] to post more about it.

Sure is nice-looking, don’t you think? That’s because there some great details at play here, like the legend-less two-tone keycaps and the neat-o locking box it sits in.

This keyboard is inspired by the Hacoa Ki-board, which uses a singles plank of wood to craft the keycaps. [Kelvin] wanted to try this technique for themselves. Evidently this won’t be the last wooden keyboard, so stay tuned for more over on Hackaday.io.

This isn’t the first dead-tree keyboard we’ve seen around here, either. A while back we saw one with Scrabble tile keycaps, and earlier this year, a nice wooden macro pad.

Continue reading “Keebin’ With Kristina: The One With The Arboreal Keyboards” →

Ordering Pizza While Racing

October 9, 2023 by Matthew Carlson 6 Comments

As [Matt Stele] prepared to bike a local 300-mile (~480km) race in addition to training, he had to prepare for food. A full day of riding was ahead on gravel trails, and one of the best options for him was Casey’s General Store pizza. However, as it was a race, other riders were much faster than him. So, all the hot slices were gone when he arrived. With the help of a serverless GPS tracker, some cloud lambdas, and some good old-fashioned web scraping, [Matt] had a system that could order him a fresh pizza at the precise moment he needed. Continue reading “Ordering Pizza While Racing” →

Use Your Old SLR As A Digital Camera?

October 9, 2023 by Jenny List 43 Comments

Back in the late 1990s as the digital revolution overtook photography there were abortive attempts to develop a digital upgrade for 35mm film cameras. Imagine a film cartridge with attached sensor, the idea went, which you could just drop into your trusty SLR and continue shooting digital. As it happened they never materialised and most film SLRs were consigned to the shelf. So here in 2023 it’s a surprise to find an outfit called I’m Back Film promising something very like a 35mm cartridge with an attached sensor.

The engineering challenges are non-trivial, not least that there’s no standard for distance between reel and exposure window, and there’s next-to-no space at the focal plane in a camera designed for film. They’ve solved it with a 20 megapixel Micro Four Thirds sensor which gives a somewhat cropped image, and what appears to be a ribbon cable that slips between the camera back and the body to a box which screws to the bottom of the camera. It’s not entirely clear how they solve the reel-to-window distance problem, but we’re guessing the sensor can slide from side to side somehow.

It’s an impressive project and those of us who shot film back in the day can’t resist a bit of nostalgia for our old rigs, but we hope it hasn’t arrived too late. Digital SLRs are ubiquitous enough that anyone who wants one can have one, and meanwhile the revival in film use has given many photographers a fresh excuse to use their old camera the way it was originally intended. We’ll soon see whether it catches on though — the crowdsourcing campaign for the project will be starting in a few days.

Oddly this isn’t the first such project we’ve seen, though it is the first with a usable-size sensor.

3D Printed Mini Drone Test Gimbal

October 9, 2023 by Richard Baguley 4 Comments

Drones are a pain, especially mini ones. When you are designing, building (or even reviewing) them, they inevitably fly off in some random direction, inevitably towards your long-suffering dog, hit him in the butt and send him scuttling off in search of a quieter spot for a nap.

[Tristan Dijkstra] and [Suryansh Sharma] have a solution: a mini-drone test gimbal. The two are in the the Networked Systems group and the Biomorphic Intelligence Lab who use CrazyFlie drones in their work, which require regular calibration and testing. This excellent design allows the drone to rotate in three dimensions, while still remaining safely contained. That means I could test the flight characteristics of a drone without endangering my dogs important napping schedule.

Efforts involved attaching a light tether that restricts the drone until we know how the it flies, but what usually happens is that the tether gets trapped in a rotor, or the tether gets tight and the drone freaks out and crashes into the ground.

Using a gimbal is far more elegant, because it allows the drone to rotate freely in three dimensions, so the basic features of the drone can be established before you let it loose in the skies.

The gimbal was designed with the CrazyFlie in mind, but as there’s nothing more exotic holding the craft down than a zip tie, it should work with similarly sized quadcopters.

Continue reading “3D Printed Mini Drone Test Gimbal” →