A Quick And Stealthy Mobile Slot Antenna From Copper Tape

October 25, 2023 by Dan Maloney 41 Comments

[Ben Eadie (VE6SFX)] is at it again with the foil tape, and this time he’s whipped up a stealthy mobile sunroof antenna for the amateur radio operator with the on-the-go lifestyle.

You may recall [Ben]’s recent duck tape antenna for the 70-cm ham band, an ultra-lightweight design that lends itself to easy packing for portable operation. The conductors in that antenna were made from copper foil tape, a material that’s perfect for all sorts of specialized applications, like the slot antenna that he builds in the video below. In the ham world, slot antennas are most frequently seen cut into the main reflector of a direct satellite dish, often in hopes of avoiding the homeowner association’s antenna police. Even in the weird world of RF, it’s a strange beast because it relies on the absence of material in a large planar (or planar-ish) conductive surface.

Rather than grabbing an angle grinder to make a slot in the roof of his car, [Ben] created a “virtual” slot with copper tape on the inside of his car’s sunroof. His design called for a 39″ (0.99-m) slot, so he laid out a U-shaped slot to fit the window and outlined it with copper foil tape. His method was a little complex; he applied the copper tape to a transparent transfer film first, then stuck the whole thing to the underside of the glass in one go. It didn’t quite go as planned, but as he learned in the duck tape antenna, the copper tape makes it easy to repair mistakes. A BNC connector with pigtails is attached across the slot about 4″ (10 cm) up from the end of one of the short legs of the slot; yes, this looks like a dead short, but such are the oddities of radio.

Is it a great antenna? By the numbers on [Ben]’s NanoVNA, not really. But any antenna that gets you heard is a good antenna, and this one was more than capable in that regard. We’ll have to keep this in mind for impromptu antennas and for those times when secrecy is a good idea.

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Flaming Skull Hood Ornament Is Not Suitable For Use In Traffic

October 24, 2023 by Lewin Day 16 Comments

It’s one thing to mount a big skull—human or animal—to the front of your car. Really, though, a good hood skull should breathe fire to truly inspire enmity or awe. Thankfully, when [Anthony] went about modifying his ex-school bus, he was sure to equip it with suitably flaming equipment. It’s dangerous, so don’t try this one at home and melt your car, you hear?

The build started with an off-the-shelf replica cow skull, in lovely flame-resistant metal. It was then plumbed with a propane feed that could be triggered by a 12-volt solenoid. This was combined with a high-voltage coil driving a grill igniter to provide the necessary initiating spark.

To go forth with flames, first, a missile switch must be flipped up and engaged to arm the system. Then, hitting the skull-and-crossbones button will send fire surging forth from the front of the vehicle.

Alternatively, a wireless keyfob can be used, which bypasses the arming system—so leaving the remote in a pocket is ill-advised.

Amazingly, a former project posted on Hackaday served as an inspiration for this build.

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Tank Boots Are A Dangerous Way To Get Around Town

October 19, 2023 by Lewin Day 12 Comments

Rollerskates are all well and good, but they’re even more fun when they’re powered. Then again, why stick with wheels, when you can have the off-road benefits of tracked propulsion? That’s precisely what [Joel] was thinking when he built this impressive set of Tank Boots.

The build uses a set of tracks from a tracked snowblower, sourced for $50. The tracks are a simple design sans suspension, consisting of a pair of plastic wheels inside the tracks and run via a chain drive. Each snowblower track was given a metal frame with a ski boot and a motor, gearbox, and controller straight out of a power drill. Power was courtesy of a lithium-polymer battery pack.

Riding the boots isn’t easy, with falls and tumbles rather common. Regardless, they get around great offroad in a way that regular rollerblades never could. Bolted together, they make a great tank chair, too. We’ve actually looked at the benefits of tracks versus wheels before, too. Video after the break.

Can A $3200 Kit Convert Your Car To Electric Power?

October 15, 2023 by Jenny List 114 Comments

Whether hardcore petrolheads like it or not, we appear to be living through the final years of the internal combustion engine. In many countries there are legislative timetables in place for their eventual phasing out, and even those which remain in production are subject to ever more stringent emissions legislation. If there’s a problem with the EVs with which we’re expected to replace our fossil fuel vehicles it’s the cost, those things are still very expensive. An Aussie student has an interesting idea that’s won the James Dyson Prize: a low cost conversion for existing vehicles that bolts onto their rear wheel hubs.

Electric conversion of fossil fuel cars is nothing new, indeed we’ve brought you news of units designed to replace the original engine and transmission. Neither are wheel hub motors new, but the difference with this system is that it doesn’t require significant mechanical modification to the vehicle. It retains the old engine, and this motor sits inside each rear wheel.

It almost seems too good to be true, but a closer reading shows the rotor bolted on one side to the old wheel hub and on the other side to the wheel. The stator meanwhile is bolted to the existing brake caliper mountings. This would lead to a slightly wider track and a greater unsprung weight, but we can see that it would work. Besides the motor there’s a battery pack for the spare wheel well and a set of electrically-powered systems to supply the brake servo vacuum and other services. The idea is that this whole kit could be fitted for 5000 Australian dollars, which is somewhere south of $3200 USD. It’s not perfect and it still involves hauling around the dead weight of an unused engine, but we can see it might still have a niche. If, and that’s a big if, it ever makes it to market, that is.

Meshtastic And Owntracks To Kick Your Google Habit

October 11, 2023 by Jonathan Bennett 20 Comments

I have an admission to make. I have a Google addiction. Not the normal addiction — I have a problem with Google Maps, and the timeline feature. I know, I’m giving my location data to Google, who does who-knows-what-all with it. But it’s convenient to have an easy way to share location with my wife, and very useful to track my business related travel for each month. What we could really use is a self-hosted, open source system to track locations and display location history. And for bonus points, let’s include some extra features, like the ability to track vehicles, kids, and pets that aren’t carrying a dedicated Internet connection.

You can read the title — you know where we’re going with this. We’re setting up an Owntracks service, and then tying it to Meshtastic for off-Internet usability. The backbone that makes this work is MQTT, a network message bus that has really found its niche in the Home Assistant project among others. It’s a simple protocol, where clients send brief messages labeled by topic, and can also subscribe to specific topics. For this little endeavor we’ll use the Mosquito MQTT broker.

One of the nice things about MQTT is that the messages are all text strings, and often take the form of JSON. When trying to get two applications to talking using a shared MQTT server, there may need to be a bit of translation. One application may label a field latitude, and the other shortens it to lat. The glue code to put these together is often known as an MQTT translator, or sometimes an MQTT bridge. This is a program that listens to a given topic, ingests each message, and sends it back to the MQTT server in a different format and topic name.

The last piece is Owntracks, which has a recorder project, which pulls locations from the MQTT server, and stores it locally. Then there’s Owntracks Frontend, which is a much nicer user interface, with some nice features like viewing movement a day at a time. Continue reading “Meshtastic And Owntracks To Kick Your Google Habit” →

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.

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Reviving An Old Lime-E Beta Rideshare E-Bicycle

September 23, 2023 by Maya Posch 27 Comments

What do you do when you come across a cheap electric bicycle on Facebook Marketplace from a seller who has a few hundred of the same ones available? If you’re someone like [Max Helmetag], you figure that it’s probably legit since nobody would be reselling hundreds of Lime ridesharing e-bikes. Thus, it makes for an excellent project to see how usable an old ridesharing bicycle is. According to the information on the e-bike’s frame, it was manufactured in 2017, and based on the plastic still covering parts of the bike, it had barely been used, if at all.

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