Author: Dan Maloney

3373 Articles

Portable Classroom Upgrade: Smaller, Cheaper, Faster

November 20, 2016 by 7 Comments

[Eric] at MkMe Lab has a dream: to build a cheap, portable system that provides the electronic infrastructure needed to educate kids anywhere in the world. He’s been working on the system for quite a while, and has recently managed to shrink the suitcase-sized system down to a cheaper, smaller form-factor.

The last time we discussed [Eric]’s EduCase project was as part of his Hackaday Prize 2016 entry. There was a lot of skepticism from our readers on the goals of the project, but whatever you think of [Eric]’s motivation, the fact remains that the build is pretty cool. The previous version of the EduCase relied on a Ku-band downlink to receive content from Outernet, and as such needed to stuff a large antenna into the box. That dictated a case in the carry-on luggage size range. The current EduCase is a much slimmed-down affair that relies on an L-band link from the Inmarsat satellites, with a much smaller patch antenna. A low-noise amp and SDR receiver complete the downlink, and a Raspberry Pi provides the UI. [Eric]’s build is just a prototype at this point, but we’re looking forward to seeing everything stuffed into that small Pelican case.

Yes, Outernet is curated content, and so it’s not at all the same experience as the web. But for the right use case, this little package might just do the job. And with a BOM that rings up at $100, the price is right for experimenting.

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Stairwell Lights Keep Toddler With Night-Blindness Safe

November 19, 2016 by 25 Comments

A devastating diagnosis for a young child is every parent’s worst nightmare. All too often there’s nothing that can be done, but occasionally there’s a window of opportunity to make things better for the child, even if we can’t offer a cure. In that case even a simple hack, like a rapid response stairwell light to help deal with night-blindness, can make a real difference.

[Becca] isn’t yet a year old, but she and her parents carry a heavy burden. She was born with Usher Syndrome, an extremely rare genetic disease that affects hearing and vision to different degrees. In [Becca]’s case, she was born profoundly deaf and will likely lose her sight by the time she’s 10 or so. Her dad [Jake] realized that the soon-to-be-toddler was at risk due to a dark stairwell and the night-blindness that accompanies Usher, so he came up with a simple tech solution to the problem.

He chose Philips Hue LED light strips to run up the stringer of the stairs controlled by a Raspberry Pi. Originally he planned to use IFTTT for the job but the latency resulted in the light not switching on fast enough. He ended up using a simple PIR motion sensor which the Pi monitors and then uses the Hue API to control the light. This will no doubt give him a platform for future capabilities to help [Becca].

We’ve covered a few builds where parents have hacked solutions for their kids, like this custom media center for the builder’s autistic son. We suspect [Jake] has a few more tricks up his sleeve to help [Becca], and we’re looking forward to seeing how she does.

Cache Shortwave Signals For Later With This SDR Spectrum Grabber

November 18, 2016 by 6 Comments

Shortwave listening has always been a mainly nocturnal hobby. To get the real DX, one had to wait for favorable ionospheric conditions after sunset and spend hours twisting knobs while straining to pick voices from half a planet away out of the noise. But who has time for that in today’s world? And what of the poor city-dwelling SWL, with antenna limitations and often elevated noise floor in the urban jungle?
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Think Your Way To Work In A Mind-Controlled Tesla

November 18, 2016 by 11 Comments

When you own an $80,000 car, a normal person might be inclined to never take it out of the garage. But normal often isn’t what we do around here, so seeing a Tesla S driven by mind control is only slightly shocking.

[Casey_S] appears to be the owner of the Tesla S in question, but if he’s not he’ll have some ‘splaining to do. He took the gigantic battery and computer in a car-shaped case luxury car to a hackathon in Berkley last week and promptly fitted it with the gear needed to drive the car remotely. Yes, the Model S has steering motors built in, but Tesla hasn’t been forthcoming with an API to access such functions. So [Casey_S] and his team had to cobble together a steering servo from a windshield wiper motor and a potentiometer mounted to a frame made of 2x4s. Linear actuators attach to the brake and accelerator pedals, and everything talks to an Arduino.

The really interesting part is that the whole thing is controlled by an electroencephalography helmet and a machine learning algorithm that detects when the driver thinks “forward” or “turn right.” It translates those thoughts to variables that drive the actuators. Unfortunately, space constraints kept [Casey_S] from really putting the rig through its paces, but the video after the break shows that the system worked well enough to move the car forward and steer a little.

There haven’t been too many thought-controlled cars featured here before, but we have covered a wheelchair with an EEG interface.

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A Laser Effect Projector Built With Safety In Mind

November 17, 2016 by 29 Comments

There’s just something about wielding a laser pointer on a dark, foggy night. Watching the beam cut through the mist is fun – makes you feel a little Jedi-esque. If you can’t get enough of lasers and mist, you might want to check out this DIY “laser sky” effect projector.

The laser sky effect will probably remind you of other sci-fi movies – think of the “egg scene” from Alien. The effect is achieved by sweeping a laser beam in a plane through swirling smoke or mist. The laser highlights a cross section of the otherwise hidden air currents and makes for some trippy displays. The working principle of [Chris Guichet]’s projector is simplicity itself – an octagonal mirror spun by an old brushless fan motor and a laser pointer. But after a quick proof of concept build, he added the extras that took this from prototype to product. The little laser pointer was replaced with a 200mW laser module, the hexagonal mirror mount and case were 3D printed, and the mirrors were painstakingly aligned so the laser sweeps out a plane. An Arduino was added to control the motor and provide safety interlocks to make sure the laser fires only when the mirror is up to speed. The effect of the deep ruby red laser cutting through smoke is mesmerizing.

If laser sky is a little too one-dimensional for you, expand into two dimensions with this vector laser projector, and if monochrome isn’t your thing try an RGB vector projector.

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Another Kind Of Cloud: The Internet Of Farts

November 16, 2016 by 33 Comments

It’s taken as canon that girls mature faster than boys. In reality, what happens is that boys stop maturing at about age 12 while girls keep going. And nothing tickles the fancy of the ageless pre-teen boy trapped within all men more than a good fart joke. To wit, we present a geolocating fart tracker for your daily commute.

[Michel] is the hero this world needs, and although he seems to have somewhat of a preoccupation with hacks involving combustible gasses, his other non-methane related projects have graced our pages before, like this electrical meter snooper or an IoT lawn mower. The current effort, though, is a bit on the cheekier side.

The goal is to keep track of his emissions while driving, so with a PIC, an ESP8266, a GPS module, and a small LCD display and keyboard, he now has a way to log his rolling flatulence. When the urge overcomes him he simply presses a button, which logs his location and speed and allows him to make certain qualitative notes regarding the event. The data gets uploaded to the cloud every Friday, which apparently allows [Michel] to while away his weekends mapping his results.

It turns out that he mainly farts while heading south, and he’s worried about the implications both in terms of polar ice cap loss and how Santa is going to treat him next month. We’re thinking he’s got a lock on coal — or at least activated charcoal.

Our beef with this project is obvious – it relies on the honor system for input. We really need to see this reworked with an in-seat methane detector to keep [Michel] honest. Until then, stay young, [Michel].

Getting A Handle On ESR With A Couple Of DIY Meters

November 14, 2016 by 11 Comments

Got a bunch of questionable electrolytic caps sitting in your junk bin? Looking to recap a vintage radio chassis? Then you might need to measure the equivalent series resistance of the capacitors, in which case this simple five-transistor ESR meter might come in handy.

Even if you have no need for an ESR meter, [W2AEW]’s video below is a solid introduction to how ESR is determined. The circuit itself comes from EEVBlog forum user [Jay-Diddy_B] and is about as simple as such a circuit can get. Two transistors form an oscillator that generates a square wave that drives a resistor bridge network. The two legs of the bridge feed matched common-emitter amps, one leg through the device under test. The difference in voltage between the two legs is read on a meter, and you have a quick and simple way to sort through the caps in your junk bin. [Jay-Diddy_B]’s circuit is only presented in breadboard form; no attempt was made to field a practical instrument. Indeed, [W2AEW] already built a home-brew ESR meter using hex inverters and op amps to which he compares the five-transistor circuit’s results. His intention here seems to be to clarify the technique of ESR measurement and evaluate an even simpler circuit than his. We think he’s done a good job on both counts.

We’ve featured plenty of [WA2AEW]’s work before, like this Michigan Mity-Mite transmitter or his primer on oscilloscopes. We really like his laid back style and the way he makes complex topics easy to understand. Check them out.

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