Fail Of The Week: Battery Pack Jack Wired Backwards

March 6, 2016 by 49 Comments

Last Saturday I had a team of teenage hackers over to build Arduino line-following robots from a kit. Everything went well with the mechanical assembly and putting all the wires on the correct pins. The first test was to check that the motors were moving in the proper direction. I’d written an Arduino program to test this. The first boy’s robot worked fine except for swapping one set of motor leads. That was anticipated because you cannot be totally sure ahead of time which way the motors are going to run.

The motor’s on the second robot didn’t turn at all. As I checked the wiring I smelled the dreaded hot electronics smell but I didn’t see any smoke. I quickly pulled the battery jack from the Arduino and – WOW! – the wires were hot. That didn’t bode well. I checked and the batteries were in the right way. A comparison with another pack showed the wires going into the pack were positioned properly. I plugged in another pack but the motors still didn’t run.

I got my multimeter, checked the voltage on the jack, and it was -5.97 V from center connector to the barrel. The other pack read 6.2 V. I had a spare board and pack so swapped those and the robot worked fine. Clearly the reverse polarity had zapped the motor control ICs. After that everyone had a good time running the robots on a course I’d laid out and went home pleased with their robots.

Wires going into pack were correct.
Shaved jack showing positive lead on outside of jack.

After they left I used the ohmmeter to check the battery pack and found the wiring was backwards, as you can see in the feature photo. A close inspection showed the wire with a white line, typically indicating positive, indeed went to the positive battery terminal. I shaved the barrel connector down to the wires and the white line wire was connected to the outside of the barrel. FAIL!

This is a particularly bad fail on the part of the battery pack supplier because how hard is it to mess up two wires? You can’t really fault the robot kit vendor because who would expect a battery pack to be bad? The vendor is sending me a new battery pack and board so I’m satisfied. Why did I have an extra board and pack, actually an entire kit? For this exact reason; something was bound to go wrong. Although what I had imagined was for one of the students to break a mechanical part or change wiring and zap something. Instead, we were faced with a self-destructing kit. Prudence paid off.

Faking A Hollow State Device

March 6, 2016 by 30 Comments

There’s been a resurgence of interest in vacuum tubes. Even if you do think audio sounds better through a tube, you have to admit the care and feeding of filaments and plate voltages isn’t trivial. [Ed Nisley] decided to sidestep all that and just build an objet d’art that looks like a tube.

A burned out halogen bulb stands in for the tube, and a ceramic base holds the bulb. It also conceals–what else–an Arduino. The Arduino drives a knock-off Neopixel LED hidden in a faux plate cap. The result is a glass envelope bathed in a cold blue and purple glow that changes under software control.

We’d really like to see this kind of tube inside some rebuilt piece of tube gear. Or maybe Korg should offer LED lighting options for their recent tube in a chip form factor. If you really want to be a top-tier tube hacker, you can always try your hand at repair.

Bringing Nautical Charts To A Sunlight Readable Display

March 5, 2016 by 20 Comments

Road atlases are still published, but you wouldn’t know it if you have a smartphone and Google Maps. Most pilots who got their license a decade ago started on paper maps, but the iPad rules the cockpit today. On a single SD card, you can store maps for every square mile of the Earth’s surface. [Erland] figured it was high time for digital maps to go nautical and built a tablet-like device to display charts while sailing.

The Pi Chart is, of course, powered by a Raspberry Pi running a few dozen lines of JavaScript and HTML. Software wise, there’s not much to this build save for the new OpenGL-based rendering that allows for ultra smooth map rendering.

The hardware is where this build becomes useful, and for that, [Erland] is using a sunlight readable Pixel Qi display. A Li Ion battery provides about 10 hours of runtime, and a Bluetooth enabled GPS dongle tells the Pi exactly where the boat is.

Continue reading “Bringing Nautical Charts To A Sunlight Readable Display” →

Colin Furze Gets Burned

March 5, 2016 by 83 Comments

Consider this a public service announcement. [Colin Furze], besides being a raging lunatic, seems to have the nine lives of a cat. Well, he’s not always so lucky, and now that we’ve recovered from being grossed out by the results, we’re glad that [Colin] posted this “fail” video.

Basically, he’s firing up one of his jet engines, and there’s a big fireball. He wasn’t wearing any protective clothing. This is hardly a spoiler — please don’t watch the video below if you’re grossed out by people visiting the doctor’s office to get their horrible second degree burns all up and down their forearm treated. You’ve probably learned the lesson already just by looking at the preview image.

Naturally, we’ve covered [Colin]’s videos before. He’s either very lucky or a little bit more careful than he lets on. We’ve seen him play with fire and not get burned, and stick a jet engine on a go-kart. We’re not gonna tell you what to do, but if that were us, we’d be wearing at least long sleeves and a helmet.

Continue reading “Colin Furze Gets Burned” →

Ultimate Battery Backup Mod

March 5, 2016 by 90 Comments

Unless your main workstation is a laptop, you’ve probably got a APC or similar battery backup kicking around. But have you ever thought of modifying it to make it a bit more useful? After all, it can be used as a useful DC power supply…

[The 8-Bit Guy] shows us how he modified his APC to include a voltage readout, and direct DC output jacks. As it turns out you can get a lot more battery life if you’re not using the built-in pesky AC/DC power inverter! Stick around after the break for a very informative video on how he did it.
Continue reading “Ultimate Battery Backup Mod” →

Teensy 3.1 Controlled VFO

March 5, 2016 by 27 Comments

[Tom Hall], along with many hams around the world, have been hacking the Silicon Labs Si5351 to create VFOs (variable frequency oscillators) to control receivers and transmitters. You can see the results of his work in a video after the break.

vfo board[Tom] used a Teensy 3.1 Arduino compatible board, to control the Si5351 mounted on an Adafruit breakout board. An LCD display shows the current frequency and provides a simple interface display for changing the output. A dial encoder allows for direct adjustment of the frequency. The ham frequency band and the frequency increment for each encoder step are controlled by a joystick. When you get into the 10 meter band you definitely want to be able to jump by kHz increments, at least, since the band ranges from 28 MHz to 29.7 MHz.

So what is the Si5351? The data sheet calls it an I2C-Programmable Any-Frequency CMOS Clock Generator + VCXO. Phew! Let’s break that down a bit. The chip can be controlled from a microprocessor over an I2C bus. The purpose of the chip is to generate clock outputs from 8 kHz to 160 MHz. Not quite any frequency but a pretty good range. The VCXO means voltage controlled crystal oscillator. The crystal is 25 MHz and provides a very stable frequency source for the chip. In addition, the Si5351 will generate three separate clock outputs.

[Tom] walks through the code for his VFO and provides it via GitHub. An interesting project with a lot of the details explained for someone who wants to do their own hacks. His work is based on work done by others that we’ve published before, which is what hacking is all about.

Continue reading “Teensy 3.1 Controlled VFO” →

Hacklet 98 – Underwater ROVs

March 5, 2016 by 5 Comments

A few motors, propellers, a camera, maybe a wire tether, and some waterproof electronics. Throw it all together and baby you’ve got an underwater Remotely Operated Vehicle (ROV) cooking! It all sounds simple on the surface, but underwater ROVs are a tough challenge. We’ve all seen deep-sea ROVs searching the wreck of the Titanic, or working to stop the flow of oil below the Deepwater Horizon. Plenty of hackers, makers, and engineers have been inspired to build their own underwater ROVs. This week on the Hacklet, we’re spotlighting at some of the best ROV projects on Hackaday.io!

borgcubeWe start with [Tim Wilkinson] and BorgCube ROV. [Tim] has jumped into the world of underwater ROVs with both feet. BorgCube is designed to operate in the unforgiving salt waters of the Pacific Ocean. This ROV can see in stereo, as [Tim] plans to use a head mounted VR display like the Oculus Rift to control it. [Tim] wanted to use a Raspberry Pi as the brains of this robot. Since the Pi Compute module can handle two cameras, it was a natural fit. The electronic speed controls are all low-cost Hobby King R/C car units. [Tim] created a custom circuit board to hold all 12 ESCs. This modular design allows individual controllers to be swapped out if one meets an untimely doom. BorgCube is just getting wet, but with 37 project logs and counting, we’re sure [Tim] will keep us posted on all the latest action!

 

lunaNext up is [MrCullDog] with Luna I ROV. Inspired by a professional underwater ROV, [MrCullDog] decided to build a deep diving unmanned vehicle of his very own. Like BorgCube above, many of Luna I’s motors and drive components come from radio controlled hobby electronics. [MrCullDog] is bringing some 3D printed parts into the mix as well. He’s already shown off some incredibly well modeled and printed thruster mounts and ducts. The brains of this robot will be an Arduino. Control is via wired Ethernet tether. [MrCullDog] is just getting started on this project, so click the follow button to see updates in your Hackaday.io Feed.

cavepearlNext up is [Edward Mallon] with The Cave Pearl Project. Not every underwater system needs motors – or even a human watching over it. The Cave Pearl Project is a series of long duration underwater data loggers which measure sea conditions like temperature and water flow. [Edward’s] goal is to have a device which can run for a year on just three AA batteries. An Arduino Pro Mini captures data from the sensors, time stamps it, and stores it to a micro SD card. If the PVC pipe enclosure keeps everything dry, the data will be waiting for [Edward] to collect months later. [Edward] isn’t just testing in a swimming pool, he’s been refining his designs in open water for a couple of years now.

 

If you want to see more under (and above) water projects, check out our updated waterborne projects list! If I missed your project, don’t be shy! Just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!