The invention of the LED is one of the most important discoveries of our times. They are everywhere, from our flashlights to household lighting and television sets. We don’t need to tell you that a project with more blinkies is better than a project with fewer blinkies. But an LED is not simply an LED; the sheer variety of LEDs is amazing, and so in this write-up, we’ll take a closer look at how to choose the right LED for your next masterpiece. Continue reading “Know Thy LED”
It’s been said that the best way to tackle the issue of childhood obesity would be to hook those children’s video game consoles up to a pedal-powered generator. Of course, this was said by [Alex], the creator of Cykill. Cykill interfaces an Xbox to an exercise bike, so to keep the video game going you’ll have to keep pedaling the bike.
While there is no generator involved in this project, it does mimic the effect of powering electronics from a one. The exercise bike has a set of communications wires, which are connected to a relay on the Xbox’s power plug. When the relay notices that the bike isn’t being pedaled enough, it automatically cuts power to the console. Of course, the risk of corrupting a hard drive is high with this method, but that only serves to increase the motivation to continue pedaling.
The project goes even further in order to eliminate temptation to bypass the bike. [Alex] super-glued the plug of the Xbox to the relay, making it extremely difficult to get around the exercise requirement. If you’re after usable energy instead of a daily workout, though, there are bikes out there that can power just about any piece of machinery you can imagine.
Digital color theory can be a tricky concept to wrap one’s mind around – particularly if you don’t have experience with digital art. The RGB color model is about as straightforward as digital color mixing gets: you simply set the intensity of red, green, and blue individually. The result is the mixing of the three colors, based on their individual intensity and the combined wavelength of all three. However, this still isn’t nearly as intuitive as mixing paint together like you did in elementary school.
To make RGB color theory more tangible, [Tore Knudsen and Justin Daneman] set out to build a system for mixing digital colors in a way that reflects physical paint mixing. Their creation uses three water-filled containers (one each for red, green, and blue) to adjust the color on the screen. The intensity of each color is increased by pouring more water into the corresponding container, and decreased by removing water with a syringe.
An Arduino is used to detect the water levels, and controls what the user sees on the screen. In one mode, the user can experiment with how the color levels affect the way a picture looks. The game mode is even more interesting, with the goal being to mix colors to match a randomly chosen color that is displayed on the screen.
The practical applications for this project may be somewhat limited, but as an interactive art piece it’s hypnotizing. And, it may just help you with understanding RGB colors for your next project.
Continue reading “A Hypnotizing Interactive Art Piece For Visualizing Color Theory”
Even if you haven’t used one, you’ve probably seen the numerous projects with the inexpensive RTL-SDR USB dongle. Originally designed for TV use, the dongle is a software defined radio that many have repurposed for a variety of radio hacking projects. However, there’s one small issue. By default, the device only works down to about 50 MHz or so. There are some hacks to change that, but the cleanest way to get operation is to add an upconverter to shift the frequency you want higher. Sounds complicated? [Qrp-Gaijin] shows how to do it with a single transistor. You can see some videos of the results, below.
Actually, [Qrp-Gaijin] built an earlier version but wasn’t satisfied with the performance. He found that his original oscillator was driving an overtone crystal at its fundamental frequency. The device worked, but only because the oscillator was putting out harmonics, including the third harmonic at the actual needed frequency (49.8 MHz).
Those with small garages might be familiar with the method of hanging a tennis ball from a ceiling to make sure they don’t hit the back wall with their car. If the car isn’t in the garage, though, the tennis ball dangling from a string tends to get in the way. To alleviate this problem, [asaucet] created a distance sensor that can tell him when his car is the perfect distance from the garage wall.
At the heart of the distance sensor is an HC-SR04 ultrasonic rangefinder and a PIC16F88 microcontroller. [asaucet] uses a set of four LEDs to alert the driver how close they are to the garage wall. [asaucet] also goes into great detail about how to use an LCD with this microcontroller for setting up the project, and the amount of detail should be enough to get anyone started on a similar project.
While this isn’t a new idea, the details that [asaucet] goes into in setting up the microcontroller, using the distance sensor, and using an LCD are definitely worth looking into. Even without this exact application in mind, you’re sure to find some helpful information on the project page.
Continue reading “Garage Distance Sensor Kicks Tennis Ball To Curb”
So you want to photograph Eclipse 2017 but you don’t want to rush out and buy an expensive DSLR just for the event? Not a problem, if you build this simple smartphone filter and occluder.
It all started innocently enough for [Paul Bryson] with his iPhone and a lens from those cheap cardboard eclipse glasses we’re starting to see everywhere. Thinking that just taping the filter over the stock lens would do, [Paul] got a painful faceful of sunshine when he tried framing a shot. Turns out the phone body was not big enough to blot out the sun, and besides, the stock lens doesn’t exactly make for a great shot. So with an iPhone telephoto lens affixed to a scrap of wood and a properly positioned filter, [Paul] has a simple rig that’ll let him get some great pre-totality shots of the eclipse, and it’ll be easy to bust out the phone for two minutes of totality selfies. Looks like this setup would be easy to adapt to other phones, too.
We’re all over Eclipse 2017, from Hackaday Eclipse Meetups in at least four different points along the path of totality to experiments on relativity to citizen science efforts so you can get in on the action too. Mark your calendars – August 21 will be here before you know it.
[Peter Jansen] is the creator of the Open Source Tricorder. He built a very small device meant to measure everything, much like the palm-sized science gadget in Star Trek. [Peter] has built an MRI machine that fits on a desktop, and a CT scanner made out of laser-cut plywood. Needless to say, [Peter] is all about sensing and imaging.
[Peter] is currently working on a new version of his pocket-sized science tricorder, and he figured visualizing magnetic fields would be cool. This led to what can only be described as a camera for magnetism instead of light. It’s a device that senses magnetic fields in two directions to produce an image. It’s cool, and oddly, electronically simple at the same time.
Visualizing magnetic fields sounds weird, but it’s actually something we’ve seen before. Last year, [Ted Yapo] built a magnetic imager from a single magnetometer placed on the head of a 3D printer. The idea of this device was to map magnetic field strength and direction by scanning over the build platform of the printer in three dimensions. Yes, it will create an image of field lines coming out of a magnet, but it’s a very slow process.
Instead of using just one magnetic sensor, [Peter] is building a two-dimensional array of magnetic sensors. Basically, it’s just a 12×12 grid of Hall effect sensors wired up to a bunch of analog multiplexers. It’s a complicated bit of routing, but building the device really isn’t hard; all the parts are easily hand-solderable.
While this isn’t technically a camera as [Peter] would need box or lens for that, it is a fantastic way to visualize magnetic fields. [Peter] can visualize magnets on his laptop screen, with red representing a North pole and green representing the South pole. Apparently, transformers and motors look really, really cool, and this is a perfect proof of concept for the next revision of [Peter]’s tricorder. You can check out a video of this ‘camera’ in action below.
Continue reading “Imaging Magnetism With A Hall Effect Camera”
