Serious DX: The Deep Space Network

Humanity has been a spacefaring species for barely sixty years now. In that brief time, we’ve fairly mastered the business of putting objects into orbit around the Earth, and done so with such gusto that a cloud of both useful and useless objects now surrounds us. Communicating with satellites in Earth orbit is almost trivial; your phone is probably listening to at least half a dozen geosynchronous GPS birds right now, and any ham radio operator can chat with the astronauts aboard the ISS with nothing more that a $30 handy-talkie and a homemade antenna.

But once our spacecraft get much beyond geosynchronous orbit, communications get a little dicier. The inverse square law and the limited power budget available to most interplanetary craft exact a toll on how much RF energy can be sent back home. And yet the science of these missions demands a reliable connection with enough bandwidth to both control the spacecraft and to retrieve its precious cargo of data. That requires a powerful radio network with some mighty big ears, but as we’ll see, NASA isn’t the only one listening to what’s happening out in deep space. Continue reading “Serious DX: The Deep Space Network”

Push Button, Receive Beverage!

Here’s a rec-room ready hack: an automatic drink dispenser.

[truebassB]’s dispenser operates around a 555 timer, adjusted by a potentiometer. Push a button and a cup pours in a few seconds, or hold the other button to dispense as much as you want.

The dispenser is made from MDF and particle board glued together, with some LEDs and paper prints to spruce it up. Just don’t forget a small spill sink for any miscalculated pours. You needn’t fret over the internals either, as the parts are easily acquired: a pair of momentary switches, a 12V micro air pump, a brass nozzle, food-safe pvc tube,  a custom 555 timing circuit — otherwise readily available online — a toggle switch, a power supply plug plus adapter and a 12V battery.

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DC Motor Whirligig Generates Power

Everyone knows that if you spin the shaft of a DC motor, it will generate power. [Vapsvus] has found a novel way to do this with no direct mechanical connection to the shaft. He simply taped a loop of string around to the motor can. This effectively turns the motor into a whirligig. Flip the motor to give the string a few twists, then pull on the two loops. The string unwinds and then winds back up, just like the toy we all grew up with.

The interesting thing is that the motor generates usable power when being spun like this. [Vapsvus] connected two LEDs to the motor’s leads to show what’s happening. The white LED glows when current travels from positive to negative, and the red LED glows when current travels from negative to positive.

What’s going on under the hood is all about momentum. As the motor can starts to spin, the heavy iron rotor remains still. Power is generated. Eventually, friction and torque from back EMF cause the rotor to spin as well. By the time the rotor is spinning, the motor can is already reversing direction.This generates even more power with current traveling in reverse.

Sure, this isn’t exactly practical, but we’d love to see how far it could be taken. Add a super capacitor, and we bet it would be more efficient than the magnetic shake lights which were popular a few years back.

Whirligigs are usefully little devices. Not only do they keep children entertained, you can use them as centrifuges.

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RF Noise Floor Concerns From Both Sides Of The Atlantic

Our feed is full of stories about the RF noise floor today, and with good reason. The ARRL reports on the International Amateur Radio Union Region 1 president, [Don Beattie, G3BJ] warning that in densely populated parts of Europe there is a danger that parts of the RF spectrum have become so swamped with noise as to be rendered unusable, while on the other side of the Atlantic we have RadioWorld reporting on similar problems facing AM broadcasting in the USA.

At issue are the usual suspects, interference from poorly shielded or suppressed domestic electronic devices, VDSL broadband, power-over-Ethernet, solar and wind power systems, and a host of other RF-spewing electronics. The combined emissions from all these sources have raised the noise level at some frequencies to the point at which it conceals all but the strongest signals. Any radio amateur will tell you that a station in a rural location will be electrically much quieter than one in a city, it seems that this effect has now reached a crescendo.

In the RadioWorld article, the author [Tom F. King] and his collaborator [Jack Sellmeyer] detail a series of tests they performed on a selection of lighting products from a quality brand, bought at a local Home Depot store. They were gathering data for a submission to the FCC enquiry on the noise floor issue we reported on last year. What they found was unsurprising, significant emissions from all the products they tested. They make some stiff recommendations to the FCC and other bodies concerned with radio spectrum to get tough with offending devices, to stay on top of future developments, and for operators of AM stations to pursue sources of interference.

It could be that there is so much equipment contributing to the noise floor that this battle is lost, but it doesn’t have to be this way. Anyone who has had to prepare a product to pass a properly carried out EMC test will tell you that the requirements are stringent, and it is thus obvious that many manufacturers are shipping products unworthy of the certification they display. It is to be hoped that the authorities will begin to take it seriously before it becomes an order of magnitude worse.

Compliance label image, Moppet65535 [CC BY-SA 3.0].

Robot Car Follows Wherever You Go

Having a pet can really make a difference to your happiness at the end of the day, but they’re also a lot of work. This project by [Ioannis Stoltidis] does something similar — minus all the responsibility. The Smart Car Follower Project is designed to track people using Bluetooth and IR and follow them around from room to room.

Submitted as part of a Master’s thesis, this project hacks a toy car and uses a key chain transmitter that sends the tracking signals. A Raspberry Pi 3 combines the Bluetooth RSSI and IR signals to make create an estimate of the position of the beacon. Arduinos facilitate the IR signaling as well as the motor control allowing the robot to chase the user around like a puppy. The whole thing also comes with obstacle avoidance using ultrasonic sensors on all sides which are good if you have a lot of furniture in the house.

You can also choose to go manual-mode and drive it around the block using a PC and gamepad. A webcam connected to the onboard computer allows a first person view of the vehicle by sending the video feed over wifi to a PC application. OpenCV is used to create the final GUI which allows you to see and control the project remotely. The source code is available for download for anyone who wants to replicate the project. Check out the video of it in action below.

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Charge Your Phone on an Iron Throne

Game of Thrones season 7 is finally here! [Hoecrux] is celebrating by building a GoT inspired cell phone charger. No, this isn’t a 3D print, nor is it vacuum molded. This iron throne was hand made from hundreds of cocktail swords. The frame of the chair is made from medium density fiberboard (MDF). The frame is covered with upholstery foam, then a layer of thin gray foam which forms the surface of the chair.

[Hoecrux] then began the painstaking process of hot gluing 600 cocktail swords to her creation. Each sword had to be modified by cutting off the loop guard. Some of the swords are bent, which was achieved with a heat gun. The completed chair was finished with a coat of black spray paint, followed by dry brushing with acrylic silver paint.

This particular iron throne charger is built for an android phone. [Hoecrux] embedded a micro USB cable in the base of the seat. If you’re of the iOS persuasion, you can substitute a lightning cable.

Check out the video after the link, and while you’re at it, get a look at this beach ready solar charger setup.

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DIY Air Cannon Snags Drones from the Sky

Who hasn’t had the experience of a pesky drone buzzing around that family picnic, or hovering over a suburban backyard where bikini-clad daughters are trying to sunbathe in peace? A shotgun used to suffice for such occasions, but with this compressed-air powered drone catcher, there’s no need to worry about illegally discharging a firearm to secure some privacy.

Before the comment line lights up with outrage, the above scenarios are presented entirely in jest. We do not condone the use of force on a drone, nor do we look favorably on those who use drones in a way that even hints at an invasion of privacy. We can all get along, and even though we hope [Make It Extreme]’s anti-drone gun will never be used in anger, it’s still a neat build that gives us lots of ideas. The rig is essentially four coaxial narrow-bore compressed-air cannons, each launching a slug attached to the corner of a lightweight net. A fairly complex set of linkages sets the spread of the barrels, and a pair of old oxygen tanks serve as reservoirs for the compressed air. A fast-acting dump valve is tripped by an interesting trigger mechanism mounted to a complicated stock and grip; we’d have liked to see more on the fabrication of that bit. The video below shows a test firing that results in a clean takedown of a drone, although we doubt the owner of the quad would characterize it as such.

This build is a bit of a departure from [Make It Extreme]’s usual fare of DIY tools like a shop-built vise or big belt sander, or their unusual vehicles like an off-road hoverboard. But it’s always great to watch a good fabrication video, no matter what the subject.

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