Day: August 25, 2017

Blast Your Battery’s Sulphates, Is It Worth It?

August 25, 2017 by 55 Comments

When a friend finds her caravan’s deep-cycle battery manager has expired over the summer, and her holiday home on wheels is without its lighting and water pump, what can you do? Faced with a dead battery with a low terminal voltage in your workshop, check its electrolyte level, hook it up to a constant current supply set at a few hundred mA, and leave it for a few days to slowly bring it up before giving it a proper charge. It probably won’t help her much beyond the outing immediately in hand, but it’s better than nothing.

A lot of us will own a lead-acid battery in our cars without ever giving it much thought. The alternator keeps it topped up, and every few years it needs replacing. Just another consumable, like tyres or brake pads. But there’s a bit more to these cells than that, and a bit of care and reading around the subject can both extend their lives in use and help bring back some of them after they have to all intents and purposes expired.

One problem in particular is sulphation of the lead plates, the build-up of insoluble lead sulphate on them which increases the internal resistance and efficiency of the cell to the point at which it becomes unusable. The sulphate can be removed with a high voltage, but at the expense of a dangerous time with a boiling battery spewing sulphuric acid and lead salts. The solution therefore proposed is to pulse it with higher voltage spikes over and above charging at its healthy voltage, thus providing the extra kick required to shift the sulphation build up without boiling the electrolyte.

If you read around the web, there are numerous miracle cures for lead-acid batteries to be found. Some suggest adding epsom salts, others alum, and there are even people who talk about reversing the charge polarity for a while (but not in a Star Trek sense, sadly). You can even buy commercial products, little tablets that you drop in the top of each cell. The problem is, they all have the air of those YouTube videos promising miracle free energy from magnets about them, long on promise and short on credible demonstrations. Our skeptic radar pings when people bring resonances into discussions like these.

So so these pulse desulphators work? Have you built one, and did it bring back your battery from the dead? Or are they snake oil? We’ve featured one before here, but sadly the web link it points to is now only available via the Wayback Machine.

A Disc Shooter For When Rubber Bands Or Nerf Darts Aren’t Enough

August 25, 2017 by 27 Comments

There are times in everybody’s life when they feel the need to shoot at things in a harmless manner. For those moments there are rubber bands and Nerf darts, but even then they feel like mere toys. If that is the point at which you find yourself, then maybe [Austin]’s home-made electric disc shooter can help.

Operation of the shooter is simple enough. A stack of 3D-printed plastic discs is loaded into a tubular magazine, from which individual disks are nudged by a motor-driven cam controlled by the trigger. Once the disc leaves the magazine it reaches a vacuum cleaner belt driven by a much more powerful motor, that accelerates the disc to ejection velocity.

The video below the break shows the gun’s construction, as well as a sequence involving the destruction of plenty of balloons, soda cans, and food items. The 3D-printed ammunition seems to us to be the weak link as in our experience it is inevitable that there is a high ammunition loss rate with these type of weapons, but maybe [Austin] has a line on some cheap filament. Either way, his disc gun looks like the kind of toy that could provide an entertaining diversion for many readers.

Continue reading “A Disc Shooter For When Rubber Bands Or Nerf Darts Aren’t Enough” →

Blinking LEDs On The Internet Of Printers

August 25, 2017 by 7 Comments

When you ask for recommendations on which 3D printer to buy, damn the cost, the Ultimaker is consistently at the top of the list. There’s a reason for the popularity of this printer — it’s easy to use, extremely high quality, and has an entire freakin’ Linux system running somewhere under the hood. That last bit is opening up a few doors to some interesting hacks, like using a 3D printer as an RGB LED.

The Doodle3D team has been playing around with the Ultimaker API to see if they can make their software work with the Ultimaker printer. The Ultimaker has RGB LEDs, so obviously the simplest proof of concept in futzing around with an API is to blink a few LEDs. The actual code was written in HTML, JavaScript, and Node in just two hours. The author admits it’s ugly, but it works. Can’t go wrong with that.

While this is just a simple test of the Ultimaker API, it’s surprisingly high up on the Google results when you search, ‘Ultimaker API’. That’s a shame, because there’s a lot of power under the hood of this printer. If you have some sort of mod you’d like to throw into the ring, here’s the Hackaday Tip Line.

You can check out the demo video of this hack below.

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Custom Cut Pinwheel Makes A Useful HVAC Duct Flow Meter

August 25, 2017 by 12 Comments

Everyone is familiar with pinwheels, and few of us haven’t crafted one from a square of paper, a stick, and a pin. Pinwheels are pretty optimized from a design standpoint, and are so cheap and easy to build that putting a pinwheel to work as an HVAC duct flow meter seems like a great idea.

Great in theory, perhaps, but as [ItMightBeWorse] found out, a homemade pinwheel is far from an ideal anemometer. His experiments in air duct flow measurements, which previously delved into ultrasonic flow measurement, led him to try mechanical means. That calls for some kind of turbine producing a signal proportional to air flow, but a first attempt at using a computer fan with brushless DC motor failed when a gentle airflow couldn’t overcome the drag introduced by the rotor magnets. But a simple pinwheel, custom cut from patterns scaled down from a toy, proved to be just the thing. A reflective optosensor counts revolutions as the turbine spins in an HVAC duct, and with a little calibration the rig produces good results. The limitations are obvious: duct turbulence, flimsy construction, and poor bearings. But for a quick and dirty measurement, it’s not bad.

Looking for an outdoor anemometer rather than an HVAC flow meter? We’ve got one made from an old electric motor, or a crazy-accurate ultrasonic unit.

Continue reading “Custom Cut Pinwheel Makes A Useful HVAC Duct Flow Meter” →

Hackaday Prize Entry: CPAP Humidifier Monitor Alarm

August 25, 2017 by 31 Comments

CPAP (Continuous Positive Airway Pressure) machines can be life-changing for people with sleep apnea. [Scott Clandinin] benefits from his CPAP machine and devised a way to improve his quality of life even further with a non-destructive modification to monitor his machine’s humidifier.

With a CPAP machine, all air the wearer breathes is air that has gone through the machine. [Scott]’s CPAP machine has a small water reservoir which is heated to humidify the air before it goes to the wearer. However, depending on conditions the water reservoir may run dry during use, leading to the user waking up dried out and uncomfortable.

To solve this in a non-invasive way that required no modifications to the machine itself, [Scott] created a two-part device. The first part is a platform upon which the CPAP machine rests. A load cell interfaced to an HX711 Load Cell Amplifier allows an Arduino Nano to measure the mass of the CPAP machine plus the integrated water reservoir. By taking regular measurements, the Arduino can detect when the reservoir is about to run dry and sound an alarm. Getting one’s sleep interrupted by an alarm isn’t a pleasant way to wake up, but it’s much more pleasant than waking up dried out and uncomfortable from breathing hot, dry air for a while.

The second part of the device is a simple button interfaced to a hanger for the mask itself. While the mask is hung up, the system is idle. When the mask is removed from the hook, the system takes measurements and goes to work. This makes activation hassle-free, not to mention also avoids spurious alarms while the user removes and fills the water reservoir.

Non-invasive modifications to medical or other health-related devices is common, and a perfect example of nondestructive interfacing is the Eyedriveomatic which won the 2015 Hackaday Prize. Also, the HX711 Load Cell Amplifier has an Arduino library that was used in this bathroom scale refurb project.

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Driverless Lorries To Be Tested On UK Roads By End Of 2018

August 25, 2017 by 43 Comments

The [BBC] is reporting that driverless semi-trailer trucks or as we call them in the UK driverless Lorries are to be tested on UK roads. A contract has been awarded to the Transport Research Laboratory (TRL) for the trials. Initially the technology will be tested on closed tracks, but these trials are expected to move to major roads by the end of 2018.

All  of these Lorries will be manned and driven in formation of up to three lorries in single file. The lead vehicle will connect to the others wirelessly and control their braking and acceleration. Human drivers will still be present to steer the following lorries in the convoy.

This automation will allow the trucks to drive very close together, reducing drag for the following vehicles to improve fuel efficiency.”Platooning” as they call these convoys has been tested in a number of countries around the world, including the US, Germany, and Japan.

Are these actually autonomous vehicles? This question is folly when looking toward the future of “self-driving”. The transition to robot vehicles will not happen in the blink of an eye, even if the technological barriers were all suddenly solved. That’s because it’s untenable for human drivers to suddenly be on the road with vehicles that don’t have a human brain behind the wheel. These changes will happen incrementally. The lorry tests are akin to networked cruise control. But we can see a path that will add in lane drift warnings, steering correction, and more incremental automation until only the lead vehicle has a person behind the wheel.

There is a lot of interest in the self driving industry right now from the self driving potato to autonomous delivery. We’d love to hear your vision of how automated delivery will sneak its way into our everyday lives. Tell us what you think in the comments below.

USB + μC = Peril?

August 25, 2017 by 50 Comments

You hear about people finding USB drives and popping them into a computer to see what’s on them, only to end up loading some sort of malware onto their computer. It got me to thinking, given this notorious vulnerability, is it really a great idea to make electronics projects that plug into a computer’s USB port? Should I really contribute to the capitulation-by-ubiquity that USB has become?

A of couple years ago I was working on an innocuous project, a LED status light running off of USB. It ran off USB because I had more complicated hopes for it–some vague notion about some kind of notification thing and also it was cool to have access to 5 V right from the ‘puter. This was about the time that those little RGB LEDs connected to USB were all the rage, like blink(1), which raised $130,000 on Kickstarter. I just wanted to make a status light of some sort and had the parts, so I made it.

My version was a small rectangular PCB from OSHPark packing a Tiny85, with a 10 mm RGB LED providing pretty much all of the functionality — no spare pins broken out. Honestly, for the amount of code on it, even the Tiny85 was overpowered. I recall thinking at the time, could my creation be misused for evil? Could some wicked programmer include malware alongside my LED-lighting Arduino sketch?

It’s absurd, of course. My meager engineering skills ought not interest anyone. On the other hand, couldn’t some heartless poltroon, the hardware equivalent of a script kiddie, make my creation into a malware-spewing Typhoid Mary of a project? It has always been the realistic consequence of building anything–that it could be misused. I’d be thrilled to the point of giddiness if someone remade one of my projects into something cool, but I’d really hate for a USB light I designed to turn into some vector into someone’s computer. But how much of that is my responsibility?

If you think I’m the only one who thinks this, go to SparkFun or Adafruit and count all of the boards with microcontrollers and USB A male plugs. Even the tiny boards like the Huzzah and Gemma use USB cables, rather than plugging directly into the computer. Granted, they are microcontrollers that realistically would be connected to a project and it might not be possible to physically move them into position and plug them in. Also requiring a charging cable does not in any way make a microcontroller board work any differently than one plugged right into the computer. I’m left wondering if I’m spazzing out over nothing, and there’s nothing we can do about our tendency to treat any electronic gizmo with a shiny case as being safe to plug into the same computer we use to pay bills.

If there is no data transfer taking place, and I’m just getting power, wouldn’t it be enough to disable (or not connect) the data pins of the USB on the circuit board? Or maybe we really have no business connecting a data connection to a microcontroller if we’re not reflashing the chip with fresh code–think I’m paranoid? Maybe you should just get power from a wall wart and leave the USB cord in the drawer. It’s one thing to urge our friends and family to steer clear of mystery plugs, but as engineers and tinkerers, do we not owe the community the benefit of our knowledge?

Of course, Hackaday contains numerous examples of USB projects, including canary for USB ports, tips on protecting your ports with two microcontrollers, a guide to stopping rubber ducky attacks, and removing security issues from untrusted USB connections. Also, has anyone used the USB condom?

Friends, let me know your thoughts on the subject. Am I a freak to steer clear of USB-powered project like my dumb LED? Leave your comments and weigh in with your opinions.