Voltage Monitor Relay Is More Than Meets The Eye

August 3, 2018 by Tom Nardi 34 Comments

Automotive components that have a hidden secondary function are usually limited to cartoons and Michael Bay movies, but this project that [Jesus Echavarria] created for a client is a perhaps as close as we’re likely to get in the near future. The final product certainly looks like a standard automotive relay, but a peek inside the 3D printed case reveals a surprisingly complex little device. It’s still technically a relay, but it uses a PIC microcontroller to decide when it should activate.

[Jesus] was given the task of creating a device that would fit into the relay box of a vehicle, and serve as a battery monitor to fire off at different voltage set points. The client also wanted the ability to configure such things as how long the device would wait before enabling and disabling the alarms once the voltage threshold has been passed. After showing the client an oversize prototype using a PIC16F88 and switching regulator, he got the OK to move on to a smaller and more cost-effective version.

The final hardware makes use of a 78M05 500 mA linear regulator, a PIC16F1824 microcontroller, and a pair of AQY211EH solid state relays. The standard five pin layout used for automotive relays allows the monitor to get power from the vehicle’s battery while providing two output channels that can be switched on and off from the microcontroller. [Jesus] says an agreement with the client prevents him from sharing some elements of the project (like the firmware source code), but he gives enough information that it shouldn’t be too hard to spin up your own version.

With the addition of something like an ESP8266, this could be an easy way to retrofit an older vehicle with “smart” features. As an example, it could potentially allow for controlling the car’s headlights and horn over Wi-Fi. Or you could hack together a theft deterrent system that refuses to power on the starter or fuel pump unless your smartphone enables the relay first.

Quadcopter Hardware Gets Classic Lake Bed Test

August 1, 2018 by Tom Nardi 6 Comments

You’d be hard pressed to find an aircraft that wasn’t designed and tested without extensive use of simulation. Whether it’s the classic approach of using a scale model in a wind tunnel or more modern techniques such as computational fluid dynamics, a lot of testing happens before any actual hardware gets bolted together. But at some point the real deal needs to get a shakedown flight, and historically a favorite testing ground has been the massive dry lake beds in the Western United States. The weather is always clear, the ground is smooth, and there’s nobody for miles around.

Thanks to [James] and [Tyler] at Propwashed, that same classic lake bed approach to real-world testing has now been brought to the world of high performance quadcopter gear. By mounting a computer controlled thrust stand to the back of their pickup truck and driving through the El Mirage dry lake bed in the Mojave Desert, they were able to conduct realistic tests on how different propellers operate during flight. The data collected provides an interesting illustration of the inverse relationship airspeed has with generated thrust, but also shows that not all props are created equal.

The first post in the series goes over their testing set-up and overall procedure. On a tower in the truck’s bed a EFAW 2407 2500kV motor was mounted on a Series 1520 thrust stand by RCBenchmark. This stand connects to the computer and offers a scripted environment which can be used to not only control the motor but monitor variables like power consumption, RPM, and of course thrust. While there was some thought given to powering the rig from the truck’s electrical system, in the end they used Turnigy 6000mAh 4S battery packs to keep things simple.

A script was written for the thrust stand which would ramp the throttle from 0% up to 70% over 30 seconds, and then hold it at that level for 5 seconds. This script was run when the truck was at a standstill, and then repeated with the truck travelling at increasingly faster speeds up to 90 MPH. This procedure was repeated for each of the 15 props tested, and the resulting data graphed to compare how they performed.

The end result was that lower pitch props with fewer blades seemed to be the best overall performers. This isn’t a huge surprise given what the community has found through trial and error, but it’s always good to have hard data to back up anecdotal findings. There were however a few standout props which performed better at high speeds than others, which might be worth looking into if you’re really trying to push the envelope in terms of airspeed.

As quadcopters (or “drones”, if you must) have exploded in popularity, we’re starting to see more and more research and experimentation done with RC hardware. From a detailed electrical analysis of hobby motors to quantifying the latency of different transmitters.

Turning A Tile Into A Car Tracker

July 29, 2018 by Steven Dufresne 40 Comments

A Tile is a small Bluetooth device which you can put on your keychain, for example, so that you can find your keys using an app on your phone. Each Tile’s battery life expectancy is one year and after that year you’re expected to trade it in at a discount for a new one. Right away your hacker senses are tingling and you know what’s coming.

[Luis Rodriguez] had switched to Samsung SmartThings and had accumulated box of these Tiles with dead batteries. So he decided a fun project would be to put a Tile in his wife’s car to track it. Given that it’s using Bluetooth, the range isn’t great for car tracking, but the Tile’s app can network with other user’s apps to widen the search area.

Since the Tile’s battery was dead, he cracked it open and soldered wires to its power terminals. He then found a handy 12 volt source in the car and added a DC to DC buck converter to step the voltage down to the Tile’s 3 volts. Finding a home for the hacked tracker was no problem for [Luis]. He was already using an ODB-II dongle for a dash cam so he tapped into the 12 V rail on that.

You’ll be surprised what you can find by hacking these small tracking devices. Here’s an example of hacking of a fitness tracker with all sorts of goodies inside.

Our thanks to [Maave] for tipping us off about this hack.

The Apocalypse Bicycle

July 28, 2018 by Jenny List 66 Comments

It seems to be a perennial among humans, the tendency among some to expect the End Times. Whether it was mediaeval Europeans who prepared for a Biblical Armageddon at the first sight of an astronomical phenomenon, 19th-century religious sects busy expecting a Noah’s flood, cold-war survivalists with bunkers under the lawn, or modern-day preppers buying survival gear, we have a weakness for thinking that Time’s Up even when history shows us repeatedly that it isn’t. Popular culture has even told us that the post-apocalyptic world will be kinda cool, with Mad Max-style rusty-looking jacked-up muscle cars and Tina Turner belting out ballads, but the truth is likely to be a lot less attractive. Getting away from danger at faster than walking pace as a starving refugee would likely be a life-or-death struggle without the industrial supply chain that keeps our 21st-century luxury cars on the road, so something more practical would be called for.

[Don Scott] has written a paper describing an extremely straightforward solution to the problem of post-apocalyptic transport, which he calls the Apocalypse Bicycle. As you might expect it’s a two-wheeler, though it’s not the kind of machine on which you’d lead a break-away from the Tour de France peloton. Instead this is a bicycle pared down to its minimum,, without advanced materials and with everything chosen for durability and reliability. Bearings would have grease nipples, for instance, the chain would be completely enclosed for better retention of lubrication, and the wheels would be designed to have strips of salvaged tyre attached to them. Interestingly, the machine would also be designed not to attract attention, with muted matte colours, and no chrome. It occurs to us that many of the durability features of this machine are also those that appear on the rental bicycles owned by bike sharing companies that have been spread liberally on the streets of many cities.

You might wonder what use the idea might have, and why a prepper might consider one alongside their tins of survival rations. But it’s also worth considering that these machines have a real application in the here-and-now, rather than just an imagined one in an apocalyptic future. Many Hackaday readers are fortunate enough to live in countries unaffected by wars or natural disasters, but there are plenty of places today where an aid agency dropping in a load of these machines could save lives.

Apocalyptic cycling has featured little here. But we have brought you at least one bike made from wood.

Share Bike Surrenders Its Secrets To A Teardown

July 27, 2018 by Jenny List 67 Comments

If you are fortunate enough to live in a tiny settlement of no significance then perhaps you will be a stranger to bike sharing services. In many cities, these businesses have peppered the streets with bicycles secured by electronic locks for which the “open sesame” command comes through a Bluetooth connection and an app, and it’s fair to say they have become something of a menace. Where this is being written there are several competing brands of dubious market viability, to take a trip across town is to dodge hundreds of them abandoned across pavements, and every one of our waterways seems to sport one as jetsam courtesy of our ever-creative late-night drunks.

However annoying they might be, these bikes are electronic devices, and it’s thus interesting to read a teardown of one courtesy of [Electric Dreams]. The bike in question is in Australia and comes from Ofo, and it is very much worth pointing out that it is their property and prying it open is almost certainly a crime.

The bike itself is a fairly unexciting and rugged, with the electronics sitting in a module incorporating a back wheel lock sitting somewhere above where the rear brake might be. Inside is a custom board with GPS, GSM, and Bluetooth, and unexpectedly for an Aussie bike, a Netherlands SIM. Underneath the board is a motor and gearbox to activate the lock, but none of these parts are unexpected. The interesting angle of us comes from the power source, which is a D-sized lithium thionyl chloride cell, a primary cell rather than the expected rechargeable. These cells have a huge energy capacity, but at the expense of a truly nasty electrolyte and a high internal resistance which means they are limited to delivering tiny currents lest they explode. To power the radios and motor in the Ofo, the designer has added a supercapacitor which presumably charges slowly and can then dump the required power when needed.

So bike share bikes have no great surprises in their electronics but a minor one in their power source. Curiosity sated, no need for anyone else to break the law for another look. It’s interesting to see a large lithium thionyl chloride cell in the wild, and it would be even more interesting to know whether Ofo get good life from them. Maybe our commenters will know. Or perhaps someone should ask the Feds.

Thanks [xtra] for the tip.

Build A Boat With Your Buddies

July 20, 2018 by Jenny List 20 Comments

It’s probably a dream common to many groups of friends among the Hackaday readership: go away together to a sunny island some time in the summer, take a load of beer and maybe a BBQ, and build something. Some of us get close to it at hacker camps such as Toorcamp or EMF, but few do it as well as [KristianKalm] and his friends. Their time on an island resulted in a boat, and what a boat it is!

To be fair, this is not a craft you’d sail the high seas in, its unique hull design rendered in single-skin plywood might have some stability issues and probably would have difficulty maintaining structural integrity in a high sea. But it’s perfect for their summer time backwater, with its electric outboard, steering wheel, and seat from a Russian saloon car.

The plans are fairly simple, cut from two sheets of ply it has an angular pointed front, sloping sides, and a fairly narrow bottom. Our experience with river boats would have led to a wider flat-bottomed hull, but this one looks stable enough for their purposes. Everything is held together with PVA glue and extra pieces of wood over the joints, something that amazingly keeps the water at bay. It is fairly obviously a rather basic and ever some might say rather ugly boat, but we’d guess there are few readers who wouldn’t want to give it a spin as part of a summer holiday.

If this has caught your fancy, don’t panic, the Northern Hemisphere still has some summer left, and all you need to do is find a plastic barrel!

Thanks [Keith Olson] for the tip!

Let’s Talk About Elon Musk’s Submarine

July 17, 2018 by Tom Nardi 223 Comments

When word first broke that Elon Musk was designing a kid-sized submarine to help rescue the children stuck in Thailand’s Tham Luang cave, it seemed like a logical thing for Hackaday to cover. An eccentric builder of rockets and rocket-launched electric sports cars, pushing his engineering teams and not inconsiderable financial resources into action to save children? All of that talk about Elon being a real life Tony Stark was about to turn from meme into reality; if the gambit paid off, the world might have it’s first true superhero.

With human lives in the balance, and success of the rescue attempt far from assured (regardless of Elon’s involvement), we didn’t feel like playing arm-chair engineer at the time. Everyone here at Hackaday is thankful that due to the heroics of the rescuers, including one who paid the ultimate price, all thirteen lives were saved.

Many said it couldn’t be done, others said even saving half of the children would have been a miracle. But Elon’s submarine, designed and built at a breakneck pace and brought to Thailand while some of the children were still awaiting rescue, laid unused. It wasn’t Elon’s advanced technology that made the rescue possible, it was the tenacity of the human spirit.

Now, with the rescue complete and the children well on their way to returning to their families, one is left wondering about Elon’s submarine. Could it have worked?

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