Filter your Pi and be a Responsible Pirate

At this point it’s pretty well-known that you can tack a long wire to the Raspberry Pi’s GPIO, install some software, and you’ve got yourself the worlds easiest pirate FM radio station. We say that it’s a “pirate” station because, despite being ridiculously easy to do, broadcasting on these frequencies without a license is illegal. Even if you had a license, the Raspberry Pi with a dangling bit of wire will be spewing out all kinds of unintentional noise, making it a no-go for any legitimate purposes.

Unfiltered output of Pi broadcasting on 107.3 MHz

In an effort to address that issue, [Naich] has written up a couple posts on his blog which not only discuss why the Pi is such a poor transmitter, but shows how you can build a filter to help improve the situation. You’ll still be a lawless pirate if you’re transmitting on FM stations with your Pi, but you won’t be a filthy lawless pirate.

In the first post, [Naich] shows us exactly what’s coming out of the wire antenna when the Pi is broadcasting some tunes on the default 107.3 MHz, and it ain’t pretty. The Pi is blasting out signals up and down the spectrum from 50 MHz to 800 MHz, and incredibly, these harmonics are in some cases stronger than the intentional broadcast. Definitely not an ideal transmitter.

[Naich] then goes on to show how you can build a DIY filter “hat” for the Pi that not only cuts down a lot of the undesirable chatter, but even boosts the intended signal a bit. The design is surprisingly simple, only costs a few bucks in components, and conveniently is powered directly from the Pi’s GPIO. It even gives you a proper antenna jack instead of a bare wire wound around a header pin.

We’ve seen plenty of projects utilizing the Raspberry Pi FM transmission hack, and while this mod still doesn’t make it perfect, it’s always nice to see an awesome hack made even better.

The Lichtspiel: Not A Simple Child’s Toy.

For his niece’s second birthday, [Stefan] wondered what a toddler would enjoy the most? As it turns out, a box packed with lights, dials and other gadgets to engage and entertain.

For little Alma’s enjoyment, three potentionmeters control a central LED, a row of buttons toggle a paired row of more lights, a rotary encoder to scroll the light pattern of said row left and right, and some sockets to plug a cable into for further lighting effects. Quite a lot to handle, so [Stefan] whipped up a prototype using an Arduino — although he went with an ATmega 328 for the final project — building each part of the project on separate boards and connected with ribbon cables to make any future modifications easier.

[Stefan] attempted to integrate a battery — keeping the Lichtspiel untethered for ease of use — and including a standby feature to preserve battery life. A power bank seemed like a good option to meet the LED’s needed 5V, but whenever the Lichtspiel switched to standby, the power bank would shut off entirely — necessitating the removal of the front plate to disconnect and reconnect the battery every time. The simpler solution was to scrap the idea entirely and use the charging port as a power port instead — much to the delight of his niece who apparently loves plugging it in.

Continue reading “The Lichtspiel: Not A Simple Child’s Toy.”

Rotating Lithophane Box Turns with Time

If you wanted to make a rotating display box, what would you use to make it spin? A servo? A stepper motor? [ChrisN219] didn’t need his to move quickly by any means, and this opened up his options to something we probably wouldn’t have thought to use: a clock movement. Specifically, the hour minute part of the shaft.

Rotating lithophanes of your loved ones makes for a pretty cool project, and there isn’t a whole lot to this build to make it difficult. Much of it is 3D printed, including the tube in the center that the LED strip is wrapped around. The base is just big enough to hold the clock movement and the LED strip controller, so it would fit nicely on a desk or a mantel.

This is version two of [Chris]’ lithophane box, which gave him a chance to perfect the frame and design a thicker center post to withstand the heat from the LED strip. All the files are available if you want to print your own panels and take them for a spin. Since it’s so easy to change them out, you may end up with a big pile to choose from.

A Gif-Playing Top Hat For FRC 2018!

In gearing up to mentor a team at the 2018 FIRST Robotics Competition, redditor [dd0626] wanted to do something cool that resonated with this year’s 8-bit gaming theme. Over the course of a few days, they transformed a top hat into a thematically encapsulating marquee: a LED matrix display loaded with gifs!

The display is actually a sleeve — made from shipping foam, a pillow case, and an old t-shirt — that fits over the hat, leaving it intact and wearable for future events. A Teensy3.6 displays the gifs on four WS2812 16×16 RGB LED matrices, and while a sheer black fabric diffuses the light, it’s still best viewed from several feet away. This is decidedly not intended to be a stealthy hat display.

To mitigate current draw, [dd0626] is using a 5V 30A DC/DC converter and keeping the brightness at a minimum — otherwise, each panel can pull up to 15A! To offset any dip in performance, they’ve bundled in a massive 22,400mAh, 24V battery pack to keep the hat running for a while. Despite all the hardware, the hat weighs under two pounds — eminently wearable for a long day of competition. Continue reading “A Gif-Playing Top Hat For FRC 2018!”

Is This The End For The C.H.I.P.?

There have been so many launches of very capable little single-board computers, that it is easy to forget an individual one among the crowd. You probably remember the C.H.I.P though, for its audacious claim back in 2015 to be the first $9 computer. It ran Linux, and included wireless connectivity, composite video output, and support for battery power. As is so often the case with ambitious startups, progress from the C.H.I.P’s creator Next Thing Co came in fits and starts.

In recent months there has been something of a silence, and now members of the community have discovered evidence that Next Thing CO are the subject of a Notice of General Assignment from Insolvency Services Group. This is followed up by the discovery that their office is available for rent.

A process called Assignment to the Benefit of Creditors is an alternative to bankruptcy proceedings yet still signals the end of a company as the service liquidates remaining assets. Despite the website and forum remaining online it appears that we may have seen the end of the C.H.I.P. and its stablemates. Hackaday has reached out to Next Thing Co for comment and will update this article if we hear back.

At the time it was launched, the C.H.I.P. was a pretty impressive product, and though it has since been eclipsed by products like the Raspberry Pi Zero, the board remains a useful item. The addition of the PocketCHIP all-in-one keyboard and display peripheral made it an instantly recognizable device, and it and its more powerful companion C.H.I.P. Pro module found their way into quite a few projects. For us the most impressive C.H.I.P. project is a retrocomputer, this miniature Apple II complete with monitor. If this really is the end for this particular little board, we’ll be sorry to see it go.

Thanks [smerrett79] for the tip.

Header image: Kiwamu Okabe [CC BY-SA 2.0].

Nancy Grace Roman, Mother of the Hubble

When she was four years old, Nancy Grace Roman loved drawing pictures of the Moon. By the time she was forty, she was in charge of convincing the U.S. government to fund a space telescope that would give us the clearest, sharpest pictures of the Moon that anyone had ever seen. Her interest in astronomy was always academic, and she herself never owned a telescope. But without Nancy, there would be no Hubble.

Goodnight, Moon

A view of the Milky Way from Reno, Nevada. Via Lonely Speck

Nancy was born May 16, 1925 in Nashville, Tennessee. Her father was a geophysicist, and the family moved around often. Nancy’s parents influenced her scientific curiosities, but they also satisfied them. Her father handled the hard science questions, and Nancy’s mother, who was quite interested in the natural world, would point out birds, plants, and constellations to her.

For two years, the family lived on the outskirts of Reno, Nevada. The wide expanse of desert and low levels of light pollution made stargazing easy, and Nancy was hooked. She formed an astronomy club with some neighborhood girls, and they met once a week in the Romans’ backyard to study constellations. Nancy would later reminisce that her experience in Reno was the single greatest influence on her future career.

By the time Nancy was ready for high school, she was dead-set on becoming an astronomer despite a near-complete lack of support from her teachers. When she asked her guidance counselor for permission to take a second semester of Algebra instead of a fifth semester of Latin, the counselor was appalled. She looked down her nose at Nancy and sneered, “What lady would take mathematics instead of Latin?”

Continue reading “Nancy Grace Roman, Mother of the Hubble”

Handheld Propulsion Is Noisy, Awesome

Lithium batteries are ubiquitous, cheap, and incredibly powerful. Combine them with some brushless DC motors and you’ve got serious power in a compact package. [Ivan Miranda] decided to use this to his advantage, building the Handheld Self Propelling System #1. 

Yes, we’ll come right out and say it – it’s a giant fan, and it blows. Or more accurately, it’s four moderately sized fans in one fetching wrist-mounted package. The one thing that seems completely absent from the video is an answer to the obvious question – why? Other than doing damage to the hearing of anyone nearby in an enclosed space, [Ivan] demonstrates its use with the help of a skateboard in the back end of the video.

It’s built with off-the-shelf RC parts and the body is 3D printed. This is the kind of print you want to get right first time – it takes several days to print and uses a significant amount of filament.

Overall, it’s a terrifying device that promises to do something awesome when finished. [Ivan]’s just finished the thrust test and we can’t wait to see what comes next. 

If you’re looking for another way to propel yourself on a skateboard, well – there’s always the more conventional electric path.