An Open-Source Ebike Motor Controller

November 8, 2023 by Bryan Cockfield 18 Comments

DIY e-bikes are often easy to spot. If they’re not built out of something insane like an old washing machine motor, the more subtle kits that are generally used still stand out when compared to a non-assisted bike. The motors tend to be hub- or mid-drive systems with visible wires leading to a bulky battery, all of which stand out when you know what to look for. To get a stealthy ebike that looks basically the same as a standard bicycle is only possible with proprietary name-brand solutions that don’t lend themselves to owner repair or modification, but this one has at least been adapted for use with an open source motor controller.

The bike in use here is a model called the Curt from Estonian ebike builder Ampler, which is notable in that it looks indistinguishable from a regular bicycle with the exception of the small 36-volt, 350-watt hub motor somewhat hidden in the rear wheel. [BB8] decided based on no reason in particular to replace the proprietary motor controller with one based on VESC, an open-source electric motor controller for all kinds of motors even beyond ebikes. Installed on a tiny Arduino, it fits inside the bike’s downtube to keep the stealthy look and can get the bike comfortably up to around 35 kph. It’s also been programmed to turn on the bike’s lights if the pedals are spun backwards, and this method is also used to change the pedal assist level, meaning less buttons and other user-interface devices on the handlebars. Continue reading “An Open-Source Ebike Motor Controller” →

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.

Continue reading “A Quick And Stealthy Mobile Slot Antenna From Copper Tape” →

Active Camouflage Material Shows Promise At Hiding From Infrared Or Visual Detection

January 7, 2021 by Lewin Day 21 Comments

An invisibility cloak may seem like science fiction, but despite that, many scientists and engineers have put much time into developing the concept, pushing it closer to reality. A device which detects the nature of its surroundings and changes its own properties to blend in may be complex, but a multitude of examples in the animal world show that it’s not impossible to achieve.

A team from Seoul National University recently developed a flexible material designed in part as a flexible “cloaking” material. We’ll take a look at the underlying concept behind such devices below, and look at how this work furthers the state of the art in the field.

Continue reading “Active Camouflage Material Shows Promise At Hiding From Infrared Or Visual Detection” →

Plasma “Ghosts” May Help Keep Future Aircraft Safe

May 18, 2020 by Tom Nardi 34 Comments

Air-to-air combat or “dogfighting” was once a very personal affair. Pilots of the First and Second World War had to get so close to land a hit with their guns that it wasn’t uncommon for altercations to end in a mid-air collision. But by the 1960s, guided missile technology had advanced to the point that a fighter could lock onto an enemy aircraft and fire before the target even came into visual range. The skill and experience of a pilot was no longer enough to guarantee the outcome of an engagement, and a new arms race was born.

An F-15 launching flare countermeasures.

Naturally, the move to guided weapons triggered the development of defensive countermeasures that could confuse them. If the missile is guided by radar, the target aircraft can eject a cloud of metallic strips known as chaff to overwhelm its targeting system. Heat-seeking missiles can be thrown off with a flare that burns hotter than the aircraft’s engine exhaust. Both techniques are simple, reliable, and have remained effective after more than a half-century of guided missile development.

But they aren’t perfect. The biggest problem is that both chaff and flares are a finite resource: once the aircraft has expended its stock, it’s left defenseless. They also only work for a limited amount of time, which makes timing their deployment absolutely critical. Automated dispensers can help ensure that the countermeasures are used as efficiently as possible, but sustained enemy fire could still deplete the aircraft’s defensive systems if given enough time.

In an effort to develop the ultimate in defensive countermeasures, the United States Navy has been working on a system that can project decoy aircraft in mid-air. Referred to as “Ghosts” in the recently published patent, several of these phantom aircraft could be generated for as long as the system has electrical power. History tells us that the proliferation of this technology will inevitably lead to the development of an even more sensitive guided missile, but in the meantime, it could give American aircraft a considerable advantage in any potential air-to-air engagements.

Continue reading “Plasma “Ghosts” May Help Keep Future Aircraft Safe” →

Ask Hackaday: How Did They Shoot Down A Stealth Aircraft?

August 15, 2014 by Will Sweatman 207 Comments

It was supposed to be a routine mission for U.S. Air Force Lt. Col. Darrell P. Zelko, a veteran pilot of the 1991 Gulf War. The weather over the capital city of Serbia was stormy on the night of March 27th, 1999, and only a few NATO planes were in the sky to enforce Operation Allied Force. Zelco was to drop 2 laser guided munitions and get back to his base in Italy.

There was no way for him to know that at exactly 8:15pm local time, a young Colonel of the Army of Yugoslavia had done what was thought to be impossible. His men had seen Zelco’s unseeable F117 Stealth Fighter.

Seconds later, a barrage of Soviet 60’s era S-125 surface-to-air missiles were screaming toward him at three times the speed of sound. One hit. Colonel Zelco was forced to eject while his advanced stealth aircraft fell to the ground in a ball of fire. It was the first and only time an F117 had been shot down. He would be rescued a few hours later.

How did they do it? How could a relatively unsophisticated army using outdated soviet technology take down one of the most advanced war planes in the world? A plane that was supposed be invisible to enemy radar? As you can imagine, there are several theories. We’re going deep with the “what-ifs” on this one so join us after the break as we break down and explore them in detail.

Continue reading “Ask Hackaday: How Did They Shoot Down A Stealth Aircraft?” →

Stealth Camper Van

January 23, 2014 by Mike Szczys 84 Comments

Sometimes you need to sleep where you’re not supposed to. In this case, [MisterE] wanted to cut the costs associated with his climbing trips. He took a 2001 GMC Savana cargo van and turned it into a stealthy mobile living space. The project is from back in 2008 and we almost waved off from featuring it. But when you start to look at all of the creative space-saving solutions in the hack we think you’ll agree it’s worth a look.

Since he’s a climber that means time in the mountains, which can be quite cold. The sides and floor of the van were insulated to about R19 before the build work itself started and there’s a small wall-mounted heater. For comfort, a fouton was a must for sleeping but also for its double use as a sofa. For style the only choice here was bead-board to cover all of the walls. There is a small kitchenette that is mainly just a sink (we’ve seen running water in vehicles before). A couple of extra batteries power all of the electronics: audio, laptop, etc. When asked, [MisterE] confirms that he added hidden storage areas for his more pricey gear. Total cost on the project came it at $11,500. About nine for the van and the rest for improvements.

He mentions he blew an inverter because of grounding issues while starting the van. As long as he turns it off before start-up he’s fine. Shouldn’t there be a better way to build protection into this? Please leave a comment after the break and let us know what you’d do differently.

[Thanks Mac]

The Future Of Annoyance

December 19, 2008 by Eliot 44 Comments

ae83_phantom_keystroker_v2

[Garrett] posted about ThinkGeek updating the Phantom Keystroker to support random capslocking. You may remember that [Garrett] built the Stealth USB CapsLocker for April Fool’s day. The tiny device would randomly turn on the victim’s Caps Lock. This update to the commercial product has inspired him to refresh his own design. He suggests few possible options: random inserts, erratic volume control, or random sleeps. He’s also planning on making it more accessible to hacking. What would you add?