Electronic Table Top Catapult

April 30, 2012 by 14 Comments

[Unusualtravis] came up with this fairly slick electronic catapult. This easy to construct and moderately cheap rig has an arduino as the brains and controls for 3 servos. One is the release, another controls tension, and the third controls the angle. Both the circuit and the construction are very simple making this a perfect weekend project. He would have preferred it to be a bit smaller, so shoot him your design if you manage to shrink it.

We’ve always been rather fond of catapults of whatever complexity, so feel free to send in any variations you’ve worked on.

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Automated Turntable Photography

April 11, 2012 by 3 Comments

[Muris] has a friend who is selling items on the internet. This friend wanted a simple way to make rotating images of the products and asked him to help. The result of his labors is this base unit that drives the turn table and controls the camera.

The first iteration of the turntable was powered by the stepper motor from a floppy drive. A disc was mounted directly on the motor spindle, but the results were a bit poor. This is because the motor had a fairly low resolution of 200 steps per rotation. That doesn’t allow for smooth animation, and there was a lot of vibration in the system. An upgrade to the geared system you see above included swapping out that motor for one from an old scanner. Now it achieves 1200 steps per rotation and the vibration is gone.

The connectors seen in the base are USB, incoming power, and shutter control. [Muris] wrote a program to control the PIC 16F628A inside the base. The program sends commands via USB and has parameters for number of frames per rotation, direction of rotation, and the like. Set it up as desired, place the product on the turntable, and hit start. Unfortunately there’s no video of this in action because [Muris] gave it to his friend as soon as it was finished. We guess the fact that he didn’t get it back means it’s working great.

If you don’t mind some rough edges and exposed wiring you can throw a system of your own together pretty quickly.

Music Box Is Still Alive With Wavetable Synthesis

January 17, 2012 by 20 Comments

For all the wonder of dulcet tones coming from a century-old music box, we’ve got to admit that [Markus]’ wavetable synthesis build is still pretty impressive. Of course, the Internet cred gained by doing a demo of Still Alive helps too.

Wavetable synthesis stores a one cycle long waveform in RAM that can be played on a loop at varying frequencies. This technique has been around since the late 70s and can be found in a lot of the classic synths of the 80s and serves as the basis for Atari MOD music and the Game Boy chiptunes produced with Little Sound DJ

[Markus] found a pair of battery-powered laptop speakers and decided a music box would be a wonderful project. Inspired by [ChaN]’s ATtiny wavetable synthesizer, [Markus] decided to up the ante and use a PIC32 microcontroller to make the programming a little more digestable. The entire project (with an awesome dead bug soldering job) is nearly as large as the PIC itself.

[Markus] threw up the source code along with some Python scripts to convert waveforms and MIDI files into something the chip can understand. Before you check that out, be sure to look at the Still Alive demo.

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Handheld Jaguar Makes 32 Or 64 Bits Portable

December 22, 2011 by 4 Comments

There’s nothing wrong with portable NESs, Super Nintendos, N64, or even a portable Sega CD. What about a portable version the oft-maligned Atari Jaguar, though? [Evil Nod] pulled it off, and it looks great.

The build is fairly standard for a portable console. A PS1 screen is used for the display, and a cut up and re-wired controller provides the input. From what we see on the build log, moving the 104-pin cartridge slot onto ribbon cables was an exercise in patience. The case is absolutely phenomenal with a textured finish we would expect to see on an early 90s console. Of course, [Nod] kept the numeric keypad; there was space left over anyway.

We can’t rag on the Jaguar or [Nod]’s build. It’s a great execution and there’s an impressive library of games that include Worms, Rayman, Doom, and Myst. Still, we wonder what the build would look like with the Jaguar CD-ROM attached.

Oh Boy Do We Want To Ride A Giant Inflatable Robot

November 23, 2011 by 11 Comments

We’ve seen videos of people attaching chairs to gigantic welding robots and riding them around the shop, and while that would be fun for a little bit, the joy would be fleeting. Flight simulators built on a Stewart Platform are becoming old hat. Now there’s a new robot we want to ride.

[Saul Griffith] from Otherlab has been working on pneumatic robots for some time now, and he just wrapped up his Ant-Roach build seen above. It’s a 15-foot-long cross between an anteater and a cockroach that’s completely inflatable and can actually walk with the help of an air compressor.

The ‘muscles’ of the ant-roach are fabric actuators that contract when inflated. Of course this makes the mechanics look like something out a biology book, but the robot is still a neat piece of engineering. The ant-roach weighs in at 70 pounds but could probably support a half-ton of riders.

From the videos after the break, we can see that the ant-roach looks a little clumsy when walking. [Travis Deyle] sent in his contribution that details an amazing inflatable robotic arm that can beat any human in an arm wrestling match. Now we can’t wait for a giant anthropomorphized bouncy castle to start lumbering to a children’s carnival.

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Simple Hack Reuses An Air Freshener PIR Sensor

October 11, 2011 by 5 Comments

pir_sensor_room_greeter

A year ago [Lochie] bought an Airwick automatic air freshener, and while he thought it was a cool gadget, the freshening spray and the novelty ran out in short order. The device collected dust in his room for some a while until he recently unearthed it, and noticed that a perfectly good PIR sensor was looking him in the face all this time.

He disassembled the air freshener, then set out to figure out how he could interface with the PIR sensor. After finding a helpful Instructable on the topic, he had full access to the sensor’s signals, allowing him to easily wire it up to an Arduino. He decided it would be fun to trigger some simple music any time someone entered his room, so he encoded a short bit of the Super Mario Brothers theme in RTTTL, as he explains in the video below.

It’s a simple little hack, but [Lochie] is pleased with it, and we imagine that he likely has a long list of other creative ideas in mind for his newly discovered PIR sensor.

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Transformer-based PSU Repair

September 13, 2011 by 19 Comments

Repairing someone else’s design mistakes is much more difficult than starting from scratch. So whenever we come across someone who’s good at this type of trouble-shooting we pay attention. [Jim] had a Sangean HDR-1 in his home. It’s a tabletop HD radio that stopped powering up for some reason. He cracked it open and got to the bottom of the problem.

The first order of business is disassembly, which isn’t too hard with this model. With multimeter in hand he started probing the transformer and found that the contacts for the primary are an open circuit; signaling a problem. There’s no inline fuse for protection, and further study of the secondary winding let him to discover the use of 1N5817 diodes. These are underrated parts for this particular transformer. He replaced them with 1N4003 diodes to bring the device in spec. But there was still the issue of fuse protections. A bit of circuit free-forming allowed him add a fuse and varistor  by soldering the directly to the transformer’s contacts.

Why stop there? While [Jim] had the case open he also swapped out the low-end op-amp and a few electrolytic capacitors to improve the sound quality of the radio. Op-amp replacement seems to be a popular way to improve the sound from HD radios.