Isolated Voltage Measurements Through Frequency

July 16, 2016 by Elliot Williams 23 Comments

This one’s not a flashy hack, it’s a great piece of work and a good trick to have up your sleeve. Sometimes you’ve got a voltage difference that you’d like to measure, but either the ground potential is at a different level, or the voltages are too high for your lowly microcontroller.

There are tons of tricks with resistive voltage dividers that you can play. But if you want serious electrical isolation from the target, there’s only one way to go — an optocoupler. But optocouplers only really transmit digital signals, and [Giovanni Carrera] needed to measure an analog voltage.

Enter the voltage-to-frequency IC that does just what it says: produces a square wave with a frequency that’s proportional to the voltage applied. Pass this square wave through an optocoupler, and you can hit one side with voltages approaching lightning strikes without damaging the microcontroller on the other side. And you’re still able to measure the voltage accurately by measuring the frequency on the digital I/O pins of the microcontroller.

[Giovanni] built up and documented a nice circuit. He even tested it for linearity. If you’re ever in the position of needing to measure a voltage in a non-traditional way, you’ll thank him later.

Your ESP8266 Needs More Memory

July 16, 2016 by Elliot Williams 44 Comments

We just got through reviewing MicroPython on the ESP8266, and one of the main takehomes is that our ESP modules need more flash memory. You may be in the same boat — the earliest (and cheapest) modules on the market only had 512 kB of flash. For over-the-air programming, or to give you some more space for fancier programs, you’re going to want 1 MB or even 4 MB.

The solution? Just buy a new flash chip and solder it on. This is especially easy if you’ve got an ESP-01, ESP-03, or ESP-11 modules where the flash chip is exposed. Desolder, resolder, done. It can be a little trickier for those modules with a tin can around chips, but that’s nothing that a little hot air can’t fix. See the video embedded below for a good walk-through.

Continue reading “Your ESP8266 Needs More Memory” →

Giant Spider Roams The Streets

July 16, 2016 by Jenny List 30 Comments

There is a giant spider the size of a house stretching its massive, delicate legs as it parades through the French city of Nantes. Is the Arthropod Apocalypse upon us? Fortunately not, for this arachnid is the latest in a series of performance pieces by a French theatre company, La Machine.

Like the rest of La Machine’s productions, this spider is a large hydraulically controlled model driven not by a computer with a single operator but by a team of operators perched inside and underneath the mechanism who turn the operation of the spider’s legs into a piece of complex choreography. They in turn are aided by a team on the street who ensure that any manoeuvres are executed safely. The spider only gives the appearance of walking as it is supported on a hydraulic arm from a wheeled vehicle that carries its power plant, so freed of the requirement for support from its legs it can move with extreme grace.

The video below shows the spider inching its way underneath a set of tram cables. There is more video on the page linked above.

Continue reading “Giant Spider Roams The Streets” →

Obsolescence As A Service

July 16, 2016 by Elliot Williams 70 Comments

Yet another Internet of Things service has left its customers in the lurch. IoT devices (mostly lightbulbs) ~~made~~ sold by Greenwave Systems stopped talking to the outside world on July 1. More specifically, the server to which they all connected (ahem, “the cloud”) has been turned off, which rules out using the bulbs with Internet-based services like IFTTT, which was a major selling point of the Things in the first place.

[Edit: We were contacted by Greenwave, and they pointed out that they merely sold the IoT devices in question. They are made by TCP, which is also responsible for cancelling the service. And TCP has a history of doing this sort of thing before.]

It’s not the first time we’ve seen IoT companies renege on their promises to provide service, and it’s surely not going to be the last. We’re preaching to the choir here, but when even Google is willing to take the PR hit to effectively brick your devices, the only protection that you’ve got against obsolescence is an open protocol.

At least the users of ~~Greenwave’s~~ TCP’s devices will continue to be able to control them from within the home. That, plus some clever hacking, will make them workable into the future. But it’s not like the convenience that was sold with the devices.

Boo to shady IoT companies! But thanks to [Adrian] for the tip.

Hackaday Prize Entry: Linear Stepper Motors

July 15, 2016 by Brian Benchoff 29 Comments

Today, your average desktop 3D printer is a mess of belts, leadscrews, and pulleys. For his Hackaday Prize entry, [DeepSOIC] is eliminating them entirely. How’s he doing this? With a linear stepper motor.

Search Google for ‘linear stepper motor’ and you’ll find a bunch of NEMA-bodied motors with leadscrews down the middle. This is not a linear stepper motor. This is a stepper motor with a leadscrew down the middle. The motor [DeepSOIC] has in mind is more like a mashup of a rack gear and a maglev train. The ‘linear’ part of this motor is a track of magnets perpendicular to the axis of the motor, with alternating polarities. The ‘motor’ part of this motor is a carriage with two field windings. It’s an unrolled stepper motor, basically, and could run a 3D printer much faster without as much slop and backlash.

Right now [DeepSOIC] is in the experimental phase, and he had a plan to print the axis of his linear stepper in ferromagnetic filament. This did not work well. The steel found in electric motors has a magnetic permeability of about 4000, while the magnetic permeability of his brand of ferromagnetic filament is about 2. Even if the idea of printing part of a motor was a complete failure, it was a great success at characterizing the properties of a magnetic 3D printing filament. That makes it a great entry for the Hackaday Prize, and a perfect example of what we’re looking for in the Citizen Science portion of the Prize.

Retrotechtacular: The US Air Force Has The Biggest Fleet

July 15, 2016 by Brian Benchoff 27 Comments

When it comes to the superlatives of aviation, there are aircraft larger than the C-5 Galaxy. [Howard Hughes]’s Spruce Goose has the largest wingspan, and the Soviet and now Ukranian Antonov AN-225 Mriya has the largest cargo capacity. When it flies in the next year or so, Scaled Composites Stratolaunch – a twin-hulled beast of a plane designed to haul rockets up to 30,000 feet – will be the aircraft with the largest wingspan and the greatest cargo capacity.

These superlatives, while completely accurate, fail to realize these huge planes are one of a kind. There is no plan to build a second Stratolaunch, and the second airframe for the AN-225 is rusting away in a field. If you want to find a fleet of enormous aircraft, there’s only one contender: the C5 Galaxy, the largest plane in the US Air Force inventory.

This video, from the USAF Archives circa 1968, goes over the design, construction, and operation of the C5 Galaxy. It covers the program beginnings, the shortcomings of earlier aircraft, and – of course – completely disregards the initial problems of the C5.

Continue reading “Retrotechtacular: The US Air Force Has The Biggest Fleet” →

Baby Monitor Rebuild Is Also ESP8266 Audio Streaming How-To

July 15, 2016 by Donald Papp 18 Comments

[Sven337]’s rebuild of a cheap and terrible baby monitor isn’t super visual, but it has so much more going on than it first seems. It’s also a how-to for streaming audio via UDP over WiFi with a pair of ESP8266 units, and includes a frank sharing of things that went wrong in the process and how they were addressed. [Sven337] even experimented with a couple of different methods for real-time compression of the transmitted audio data, for no other reason than the sake of doing things as well as they can reasonably be done without adding parts or spending extra money.

The original baby monitor had audio and video but was utterly useless for a number of reasons (French). The range and quality were terrible, and the audio was full of static and interference that was just as loud as anything the microphone actually picked up from the room. The user is left with two choices: either have white noise constantly coming through the receiver, or be unable to hear your child because you turned the volume down to get rid of the constant static. Our favorite part is the VOX “feature”: if the baby is quiet, it turns off the receiver’s screen; it has no effect whatsoever on the audio! As icing on the cake, the analog 2.4GHz transmitter interferes with the household WiFi when it transmits – which is all the time, because it’s always-on.