Eclipse Megamovie: Thousands Of Cameras For Citizen Science

August 8, 2017 by 9 Comments

On August 21, 2017, the Moon will cast its shadow across the entire breadth of the United States for the first time in almost a century. It is estimated that 12 million people live within the path in which the sun will be blotted out, and many millions more are expected to pour into the area to experience the wonders of totality.

We’d really love it if you would tell us where you’ll be during the eclipse by creating your own event page, but that’s not what this article’s about. With millions gathered in a narrow swath from Oregon to South Carolina, and with the eclipse falling on a Monday so that the prior two weekend days will be filled with campouts at prime viewing locations, I expect that Eclipse 2017 will be one big coast-to-coast party. This is an event that will attract people of all stripes, from those with no interest in astronomy that have only the faintest idea of what’s actually happening celestially, to those so steeped in the science that they’ll be calling out the exact beginning of totality and when to expect Baily’s Beads to appear.

I suspect our readership leans closer to the latter than the former, and some may want to add to the eclipse experience by participating in a little citizen science. Here’s how you can get involved.

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Touchscreen Oscilloscope

August 8, 2017 by 3 Comments

[Marco Reps] didn’t want to lug a full-sized oscilloscope around to measure his ECG while running. He decided to check out the DSO112A which is a tiny touchscreen scope from the usual China sources. The tiny one channel scope can go to 2mV/division at 2MHz and can save and recall up to 24 configurations. It also has access to the data via a serial port so you can use it as a fancy data logger. [Marco’s] video appears below.

Apparently, there is was an older model without the A on the end that was not as sensitive and had some other missing features. The price is about $70–fairly inexpensive, although not throw-away cheap.

[Marco] noted that one of the two small connectors can act as an external trigger input or a function generator. There’s the typical LiPo battery inside and a shielded input section. [Marco] tears the board down and looks at the chips on the board. Inside are two Atmel CPUs and a 20 megasample per second analog to digital converter.

The color screen looks surprisingly good in the video although, as [Marco] points out, with one channel, the colors aren’t super useful. The device also has cursors and a nice selection of measurements that work both live and on stored data.

At the end of the video, [Marco] shows a simple ECG amplifier he built from an open source schematic. We’ve covered simple ECG circuits before if you want to read more.

Last year we looked at two small inexpensive scopes. Like everything else, each year the bar gets higher. Although, in fairness, those scopes had a (reported) 25 MHz bandwidth. We’d love to see that kind of front end with the user interface of the DSO112A.

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Know Thy LED

August 8, 2017 by 82 Comments

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” →

Keep Pedaling To Keep Playing

August 8, 2017 by 12 Comments

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.

A Hypnotizing Interactive Art Piece For Visualizing Color Theory

August 8, 2017 by 4 Comments

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.

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One Transistor RTL-SDR Upconverter

August 7, 2017 by 25 Comments

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).

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Garage Distance Sensor Kicks Tennis Ball To Curb

August 7, 2017 by 24 Comments

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.

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