Ask Hackaday: Quadcopter in Near Space?

Your mission, should you choose to accept it, is to send a quadcopter to near space and return it safely to the Earth. Getting it there is not that difficult. In fact, you can get pretty much anything you want to near space with a high altitude weather balloon. Getting it back on the ground in one piece is a whole other ballgame.

Why does someone need to do this? Well, it appears the ESA’s StarTiger team is taking a card out of NASA’s book and wants to use a Sky Crane to soft land a rover on Mars. But instead of using rockets to hold the crane steady in the Martian sky, they want to use…you guessed it, a quadcopter. They’re calling it the Dropter.

quadcopter on mars

At first glance, there seems to be a lot wrong with this approach. The atmosphere on Mars is about 100 times less dense than the Earth’s atmosphere at sea level. How do props operate in these conditions? Testing would need to be done of course, and the Earth’s upper atmosphere is the perfect place to carry out such testing. At 100,000 feet, the density of the stratosphere is about the same as that of the Martian surface atmosphere. AND 100,000 feet is prime high altitude balloon territory.  Not to mention the gravity on Mars is about 38% of Earth’s gravity, meaning a 5.5 pound model on Earth could accurately represent a 15 pound model on Mars.

With all of these facts taken into consideration, one can conclude that realistic testing of a scale model Martian quadcopter is within the grasp of the hacker community. We’ve seen some work on high altitude drones before, but never a quadcopter.

Now it’s your turn to do something no one has ever done before. Think you got what it takes to pull such a project off? Let us know what your approach to the challenge would be in the comments.

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Internet Knows Your Every Move Thanks to IKEA and ESP8266

[terenceang] got his feet wet with the ESP8266 WiFi module by hacking up an IKEA Molgan PIR light. The stock PIR light simply lights when motion is detected. [terenceang] added some extra functionality to it by making it send notifications to his phone as well.

The default configuration of the stock PIR light was to only work at night. This is done with a photo diode. It was removed to make it work in daylight, along with several other components. He removed a handful of current limiting resistors to disable the hi output LEDs. One was preserved as a visual indicator. The onboard voltage regulator didn’t supply enough current for the ESP8266. [terenceang] used some electronic wizardry and was able to solve the problem with an opto-coupler.

The one thing he would change is moving from battery to mains power, as expected battery life is less than two weeks.Schematics, source code and tons of great pictures are available on his blog. If you want to give it a try but need a crash course check out the recent news that the Arduino IDE works with ESP8266, or give direct programming a try.

Control Stuff With Your Muscles

[David Nghiem] has been working with circuitry designed to read signals from muscles for many years. After some bad luck with a start-up company, he didn’t give up and kept researching his idea. He has decided to share his innovations with the hacker community in the form of a wearable suit that reads muscle signals.

It turns out that when you flex a muscle, it gives off a signal called a Surface ElectroMyographic signal, or SEMG for short. [David] is using an Arduino, digital potentiometer and a bunch of op amps to read the SEMG signals. LEDs are used to display the signal levels.

The history behind [David’s] project dates back to the late twentieth century, which he eloquently points out – “Holy crap that was a long time ago”. He worked with the MIT Aero Astro Lab and the Boston University Neuromuscular Research Center where he worked on a robotic arm for astronauts. The idea being to apply an opposing force to the arm to help prevent muscle deterioration.

Be sure to check out [David’s] extensive and well documented work, along with the several videos showing his projects at various stages of completion. If this gives you the electromyography bug, check out this guide on detecting the signals and an application of the concept for robotic prosthesis.

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Get Blown Away by the Boominator

You have a greater chance of squeezing 5 amps through a 2N2222 than you do remembering the 1980s and not thinking about the legendary ‘boom box’. They could be seen perched on the shoulders of rockers and rappers alike – many sporting the Members Only or red leather jackets. The boom boxes visual characteristics can best be described as a rectangular box with two very large speakers on each end. It is no accident that The Boominator shares these features.

[Jesse van der Zouw] did a good job of showing how he created The Boominator. It has not two, but four 10 inch woofers that delivers 360 degrees of awesomeness at 115dB. The on board battery can sustain it for up to twenty hours, and the project is topped off with some blue LED rings the encircle each speaker.

We’ve seen boom boxes here before, but this is the first with some nice LED accents. Be sure to check out this build and let us know what you might have done differently.

[via Hackaday.io]

Brighten Your Day with Motion Controlled Cabinet Light

[Thomas Snow] found himself in a bit of a pickle. His kitchen lights didn’t adequately light his counter-tops. So instead of inventing a light bending device that could warp space-time enough to get the light where it needs to go, he decided to take the easy road and installed a motion controlled LED strip under the cabinets.

Now, these aren’t just any ‘ol motion control lights. Not only is [Thomas] able to turn the lights on and off with a wave of his hand, he can control the brightness as well. He’s doing the magic with an ultrasonic range sensor and PIR sensor. An ATTiny85 ties everything together to form the completed system.

The PIR sensor was incorporated because [Thomas] didn’t want to bug his pets with the 40kHz chirp from the ultrasonic sensor. So it only comes on when the PIR sensor sees your hand. Be sure to check out [Thomas’s] project for full source and schematics.

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Lonely? Build Yourself a Chess Robot!

[Oriol Galceran] has constructed an interesting robotic chess player for his end of school project. It’s called the ChessM8, and is an impressive feat considering [Oriol] is only 17!  He’s using an Arduino Mega that connects to the host PC via a Python script.

The AI can be any chess engine that uses the Universal Chess Interface protocol, which [Oriol] points out that most of them do.  We’ve seen other chess robots here before, along with others that you can play on your wall and uses Nixie Tubes. But [Oriol’s] build is the largest of them all.

He says there’s a network of REED switches under the chess board to detect when a piece is present or not. It would be interesting to know how he dealt with debouncing issues, and if Hall Effect sensors might have been a better choice. Let us know in the comments how you would detect the chess piece.

And be sure to check out the video below to see the chess robot in action.

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Ask Hackaday: The Many Uses of Microwaves

When most think of a microwave, they think of that little magic box that you can heat food in really fast. An entire industry of frozen foods has sprung up from the invention of the household microwave oven, and it would be difficult to find a household without one. You might be surprised that microwave ovens, or reactors to be more accurate, can also be found in chemistry labs and industrial complexes throughout the world. They are used in organic synthesis – many equipped with devices to monitor the pressure and temperature while heating. Most people probably don’t know that most food production facilities use microwave-based moisture solids analyzers. And there’s even an industry that uses microwaves with acids to dissolve or digest samples quickly. In this article, we’re going to look beyond the typical magnetron / HV power supply / electronics and instead focus on some other peculiarities of microwave reactors than you might not know.

Single vs Multimode

The typical microwave oven in the millions of households across the world is known as multimode type. In these, the microwaves will take on typical wavelike behavior like we learned about in physics 101. They will develop constructive and destructive interference patterns, causing ‘hot spots’ in the cavity. A reader tipped us off to this example, where [Lenore] uses a popular Indian snack food to observe radiation distribution in a multimode microwave cavity. Because of this, you need some type of turntable to move the food around the cavity to help even out the cooking. You can avoid the use of a turn table with what is known as a mode stirrer. This is basically a metal ‘fan’ that helps to spread the microwaves throughout the cavity. They can often be found in industrial microwaves. Next time you’re in the 7-11, take a look in the top of the cavity, and you will likely see one.

Multimode microwaves also require an isolator to protect the magnetron from reflected energy. These work like a diode, and do not let any microwaves bounce back and hit the magnetron. It absorbs the reflected energy and turns it into heat. It’s important to note that all microwave energy must be absorbed in a multimode cavity. What is not absorbed by the food will be absorbed by the isolator. Eventually, all isolators will fail from the heat stress. Think about that next time you’re nuking a small amount of food with a thousand watts!

Single Mode microwaves are what you will find in chemistry and research labs. In these, the cavity is tuned to the frequency of the magnetron – 2.45GHz. This allows for a uniform microwave field. There is no interference, and therefore no hot or cold spots. The microwave field is completely homogenous. Because of this, there is no reflected energy, and no need for an isolator. These traits allow single mode microwaves to be much smaller than multimode, and usually of a much lower power as there is a 100% transfer of energy into the sample.  While most multimode microwaves are 1000+ watts, the typical single mode will be around 300 watts.

single vs multimode cavity

Power Measurement

Most microwave ovens only produce one power level. Power is measured and delivered by the amount of time the magnetron stays on. So if you were running something at 50% power for 1 minute, the magnetron would be on for a total of 30 seconds. You can measure the output power of any microwave by heating 1 liter of water at 100% power for 2 minutes. Multiply the difference in temperature by 35, and that is your power in watts.

There are other types of microwaves that control power by adjusting the current through the magnetron. This type of control is often utilized by moisture solids analyzers, where are more precise control is needed to keep samples from burning.

Have you used a microwave and an arduino for something other than cooking food? Let us know in the comments!

Thanks to [konnigito] for the tip!