Add Seinfeld Bass Riffs To Any Doorway

It’s not the most involved hack we’ve seen this week, but it’s definitely creative and made us laugh. [Grant] and some friends were joking around about how cool it would be to have sitcom-style entry music fire off every time someone came in through a door, but in real life. You know, like everyone wants to have their own theme music? This is the same idea, but the Seinfeld equivalent. (Video embedded below the break.)

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A few simple parts later (Arduino, MP3 shield, magnetic door reed switch) and a tiny bit of code to randomize which bass riff plays, and it’s a done deal. Like we said, it’s not rocket science, but it’s a humorous addition to what looks like a well-stocked game room. (Is that a Joust console we see?)

For even greater comic effect, why not add Seinfeld bass riffs to your skateboard ramps?

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Conductive Silicone Makes Flexible Circuits

Flexible circuits and wearables seem to be all the rage these days. We’ve got conductive paint, glue, and even thread. So how about conductive silicone? Well, as it turns out — it’s not that hard to make.

[Andrew Quitmeyer] has been researching flexible circuits for a while now, and recently stumbled upon an expired patent for flexible ignition cables, using carbon fibers mixed with a conductive silicone. He started playing around with it, and discovered that by dissolving pieces of carbon fiber in rubbing alcohol, letting it dry, and then mixing it into a 2-part silicone you get pretty good electrical conductivity. In fact, in the range of 40-150ohms, which is actually pretty darn impressive!

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Simple Solar Mason-Jar Lights

[Michael Mogenson] built Firefly Jar – a simple circuit to light up firefly_jar_01flickering LEDs inside a standard Mason Jar, to give away to friends and family for the holidays. Given it’s simplicity and through-hole design, it’s an ideal project for a “learn to solder” class or for those wanting to get started with building some really simple electronics. There’s just a handful of parts and putting it together shouldn’t take long. Given that he’s made available all of the source design files, it should be easy for others to spin off the project.

A 55mm solar cell fits on top of the 63.5mm diameter PCB, which in turn fits perfectly in a standard Mason Jar with a collar lid. When in the light, the solar cell charges two 1.2V NiMH batteries. This also switches off the P-channel MOSFET, turning the LED’s off. The LED’s are turned on only when the solar cell voltage is low and the Ni-Mh batteries are charged. A 2.1V LDO directly drives the two LEDs with built-in flickering circuits, eliminating the need for any further parts. Check out the video of the Firefly Jar below.

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Raspberry Pi Zero – Programming Over USB

Raspberry Pi Zero – Turning The Pi Into A USB Gadget, Over USB

[gbaman] has figured out a simpler way to program the new Raspberry Pi Zero over USB without modifying the board. Why is this useful? One example which appealed to us was setting the Zero’s USB port up as a mass storage device. Imagine plugging in your Pi powered robot, dragging and dropping a Python script into the mass storage device that shows up, and pressing a button on the robot to run the new script. Pretty fancy for $5.00.

You can get the PI to emulate a whole range of devices from a USB MIDI controller to a simple USB serial interface. We’re excited to see what uses people come up with. Unfortunately the Pi Zero is still out of stock most everywhere as we wait for the next production run to finish. Though if you’ve got one, why not check out a few of our thoughts and experiences with the device!

[gbaman] based his work off the work done by [Dave-0] and others over at the Raspberry Pi forums. [LadyAda] also has a version of this hack, which we covered, that involves soldering a header to the pi and using a UART adapter.

[via Hacker News]

SpacewΛr Comes To Life From Bonus Formlabs Printer Parts

What might you do with a few extra stereolithographic 3D printer parts? Why not make a galvo display and resurrect a couple of classic vector graphic games of yore? That’s exactly what [Matt] did. With a few extra Formlabs components and a Haskell implementation of Spacewar, [Matt] can kick back and blast his extraterrestrial foes on the surface of his Formlabs cover.

[Matt’s] source code drives the Form 2 controller board to output laser graphics on the surface of a Form 1 case. These parts might be a commodity for this Formlabs Engineer, but the output is nothing short of spectacular, given the game and USB drivers were put together from scratch. In case you want to give the Haskell source code a try, [Matt’s] kindly included an alternative software-only display using OpenGL.

Unless you’ve just upgraded from Form 1 to Form 2, odds are pretty low that you can pull this one off without breaking either your printer or your wallet. Fortunately, [Alvaro] has paved the way with a stellar galvanometer display that began as a few parts from eBay. At last! Once our Formlab printer warranties expire, we’ll know where to start looking for parts for that mosquito killer we needed.

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How To Find A Lost Drone With The Integral

If I asked you to find the area of a square, you would have no problem doing so. It would be the same if I asked you to find the volume of a cone or rectangle or any other regular shape. You might have to turn to Google to get the proper formula, but it would be a trivial process nonetheless. But what if I asked you to find the volume of some random vase sitting on a kitchen counter? How does one go about finding the volume of irregular shapes?

One way would be to fill the vase with much smaller objects of a known volume. Then you could add up the smaller volumes to get an estimate of the total volume of the vase. For instance, imagine we fill the vase with marbles. A marble is a sphere, and we can calculate the volume of each marble with the formula zeno014/3πr3. We count all of our marbles and multiply the total by the volume of a single marble and arrive at our answer. It is not perfect, however. There is a lot of empty space that exists between the marbles as they fill the vase. We are forced to conclude that our estimated volume will be lower that the actual volume.

It would be about this time when our good friend Isaac Newton would ask the question “What if you made the marbles smaller?” Reducing the size of each marble would reduce the empty space that exists between them as they pile up in the vase, giving us a more accurate total volume. But how small? Is there a limit to how small we can make them? “Do not trouble yourself with the limit.” says [Newton]. “You will find that as you make the marbles smaller and smaller, you will begin to converge on a single number – and that number will be the exact volume of your vase.”

Reducing the size of the marble to get a more exact volume demonstrates the idea of the integral – one of the two fundamental principles of The Calculus. The other principle is known as the derivative, which we explained in our previous article by taking a very careful and tedious examination of an arrow in flight. In this article, we shall take the same approach toward the integral. By the end, you will have a fundamental understanding of what the integral is, and more importantly, how it works. Our vase example gives you a good mental image of what the integral is all about, but it is hardly a fundamental understanding of it. Just how do you make those marbles smaller? To answer this question, let us look again at one of Zeno’s moving arrows.

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Open-Source Firmware For A Mini Quadrotor

Since you’re going to have to be flying your “drones” indoors anyway in the USA, at least in the US Capitol region, you might as well celebrate the one freedom you still have — the freedom to re-flash the firmware!

The Eachine H8 is a typical-looking mini-quadcopter of the kind that sell for under $20. Inside, the whole show is powered by an ARM Cortex-M3 processor, with the programming pins easily visible. Who could resist? [garagedrone] takes you through a step-by-step guide to re-flashing the device with a custom firmware to enable acrobatics, or simply to tweak the throttle-to-engine-speed mapping for the quad. We had no idea folks were doing this.

Spoiler alert: re-flashing the firmware is trivial. Hook up an ARM SWD programmer (like the ST-Link V2) and you’re done. Wow. All you need is firmware.

The firmware comes from [silverxxx], and he’s written all about it on the forum at RCGroups.com. He’s even got the code up on GitHub if you’re interested in taking a peek. It looks like it’d be fun to start playing around with the control algorithms. Next step, Skynet!

Reading the forum post, it looks like you’ll have to be a little careful to get the right model quad, so look before you leap. But for the price, you can also afford to mess up once. Heck, at that price you could throw away the motors and you’d have a tricked-out ARM dev kit.

And if you insist on hacking everything, you can probably re-purpose a wireless mouse controller to control the thing. Write your own code for the controller and you’ve got an end-to-end open firmware quadcopter for a pittance.