Zero-G Experiments Will Make Some Pretty Pictures

Does a yo-yo work in zero-g? How about a paper airplane? These questions were answered in 1985 on the Space Shuttle Discovery, but reproduction of results is the cornerstone of the scientific method. [Rob] is about to reproduce some of the awesome zero-g pictures by riding on a vomit comet and taking a few pictures of water globes colliding.

For the last few months, [Rob] has had a standby ticket on the G-Force One, a plane that takes passengers on parabolic arcs to simulate microgravity. He was lucky as his standby ticket allowed him to take a few experiments on board, so [Rob] decided there’s just not enough awesome pictures of water colliding in zero-g.

He built a rig out of micro t-slot aluminum. A DSLR is mounted to the frame along with a few ‘test tubes’ containing water. When [Rob] blows through a tube, a small sphere of water will be released to collide with other object. Think of it as the nerd’s version of water splash photography.

Of course, a trip through zero-g wouldn’t be complete without a few more experiments. [Rob] plans on testing a few toys to see if yo-yos ‘sleep’ without gravity (they don’t), and if a grandfather clock works on the moon (there’s a month-long day, so kind of). We can’t wait to see [Rob]’s pictures once he comes back to Earth.

Halloween Hacks: A Jacob’s Lantern Sure To Win The Carving Contest

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[Matt] entered himself in a pumpkin carving contest this year, even despite the fact that his artistic skills were a bit…lacking. He knew that he had very little chance of winning the contest unless he had a great gimmick to make his creation stand out, so he started brainstorming.

[Matt] figured that since his design would have to be somewhat simple, he needed something eye catching that he could add to the pumpkin after it went under the knife. Like a bolt of lightning, inspiration struck, and he set off to fetch an ignition transformer along with some wire coat hanger.

He built a makeshift Jacob’s ladder that would fit perfectly inside his hollowed out pumpkin, and proceeded to carve the pumpkin with the “Caution, risk of electric shock” logo, familiar to most anyone that works with electronics. You can see the final result in the video below, which we think looks pretty neat. If he didn’t end up winning the contest, we’d be shocked!

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Old-school Projector Turned Digital

Who hasn’t thought about turning a 1950s slide projector into a digital projector? [Matt] did, but unlike most of us, he actually did it.

[Matt]’s friend [Angus] found an old, single-slide, sans-carousel slide projector in the trash. It’s a wonderful piece of ancient technology with a fabric insulated power cord and bakelite lamp socket. This projector was upcycled to the 21st century by adding a 10 Watt LED and a Nokia 1200 LCD.

For the electronics, [Matt] used an ATmega88 microcontroller. There’s an infrared receiver so the remote from an in-car CD player can be used to advance the slides and turn the projector on and off. The LCD is controlled by a bit of bit-banging from the Mega88, using hard-coded images of Che Guevara, Hendrix, Space Invaders and some old-school Macintosh/Lisa icons. Unlike the screen printed t-shirts at American Apparel, Che is the only authentic image in this project; this projector might have been made after Guevara came to prominence.

With a 10 Watt LED, it’s not the brightest projector on the planet and the picture is a little washed out in a bright room. With dim lighting, it’s a very good project even if the images are static.

Recreating The Commodore PET With An FPGA

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[Thomas’] love affair with Commodore computers spans well over 30 years, and not too long ago he decided to recreate one of his favorite Commodore offerings, the PET. As we have seen with similar undertakings, this sort of project is no easy task, but [Thomas] seems to be making his way along nicely.

Using a Xilinx Spartan-6 FPGA on the Digilent Nexys3 dev board, he has implemented the Pet in Verilog. Like the original, his clone contains 16K of both ROM and RAM, utilizing the same simulated 6502 microprocessor he used on a previous Apple ][+ project. The FPGA version of the computer sports a 640×400 resolution which is twice that of the original, so [Thomas] simply doubled the size of each of the PET’s pixels to fill in the extra space.

[Thomas] has made some great progress so far, including the ability to load games and other programs from cassette images over a serial connection. He says that there are still a few loose ends to tie up, but it all looks good from here!

Continue reading to see a short video of Space Invaders running on he PET recreation.

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Detecting DTMF Tones From Scratch

If you’ve ever wondered about the best way to detect dial and DTMF tones from a phone line, [Debraj] is your man.

[Debraj] built a DTMF detector using the Goertzel algorithm. Normally, when we think about detecting tones, we pull FFT out of our bag of tricks. The Goertzel algorithm isn’t as computationally complex as FFT and can be implemented on even the smallest microcontrollers.

For the build, the first thing to solder is a nice audio transformer and some protection diodes. The ring tone from a phone line goes from +35 V to -35 V – a bit more than a microcontroller could handle. A PIC18F4520 dev board was used as the brain of the system with all the code is available on [Debraj]’s site.

Although implementations of the Goertzel algorithm are a little uncommon, [Debraj] has seen a few interesting projects using this technique. [Debraj]’s build could easily be modified into a guitar tuner with a few changes in the code, for example.

This project was built as the command and control for a home automation system and from the video after the break, we can’t wait for [Debraj] to get annoyed at the phrase, “To turn on the kitchen lights, please press 1…”

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Building The Second Tiniest Tetris

A few years ago, [Richard] pulled a crushed camcorder out of a junk box at a hamfest. After pulling the half-inch CRT out of the viewfinder, he needed to find a project. [Richard] ended up building the second tiniest game of Tetris we’ve ever seen.

After futzing around with the CRT, [Richard] discovered that one of the pins would accept an NTSC input. He also found a similar project that used a dime-sized CRT to play Tetris. With ready to go code, [Richard] started assembling his project into a handsome wooden box.

There are two PCBs for the build – a CRT driver circuit, and a small custom board that handles the game and controller code. The circuit for the game board was found on this site, but the featured boards there were too large for the project. A stripped-down board was fabricated by BatchPCB and put into the box.

There aren’t any controls on the console itself, for that a standard DB-9 connector was installed so a vintage Atari joystick could be used. For a more ergonomic Tetris experience, a Sega Genesis controller could be used. For something that looks like it comes out a steampunk laboratory, playing Tetris is a bit unexpected. Check out the demo video of the screen at 20x magnification after the break.

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Over Engineering A Game Of Lights Out

[Bertho] might have outdone himself this time. He built a Lights Out clone for the 7400 logic competition.

Lights Out is an electronic toy sold by Tiger in the mid 90s. The goal of the game is to turn a 5 by 5 grid of light up buttons off. There’s a catch, though – pressing a button toggles the state of the four surrounding buttons. Check out this Flash game that’s faithful to the original.

[Bertho] read a few Lights Out fan pages and set out to design the circuit. Most of the build is made up of shift registers: the ‘game state’ is saved in five 74hc164 shift registers and a 4557 programmable register. The board is set with a random number generator that toggles bits in the game register until a solvable puzzle is found. A truly spectacular build.

For the light-up buttons themselves, [Bertho] found an old Hack A Day post that describes putting tact switches underneath a LED. The project was put into a nice Plexiglas enclosure after 15 hours of soldering. [Bertho] was kind enough to put a video up of the game in action. Check it out after the break.

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