Heart-shaped heart simulator

Heart

A few years ago, [Addie] over at Tymkrs put together a spooky little Halloween project: a small Propeller board that emulates the electrical signals in a heart. As a cardiac nurse, she thought her project could use a little improvement, and after two years she’s finally done. It’s a heart-shaped board that simulates electrical signals moving through the heart.

There are several key areas that conduct electrical signals through the heart – the sinoatrial node, atrioventricular node, and bundle branches all work like players in an orchestra to keep a heart beating like it should. If something goes wrong with one of these, the heart goes into tachycardia or fibrillation – not good, by any measure. [Addie]’s board simulates all the different ways a heart can go wrong with LEDs standing in for the electrical signals in a real heart. The name of the game here is to look at the LEDs and tell what state the heart is in.

The PCB heart is just one part of [Addie]’s heart simulator. The simulated heart can also plug into a neat little heart-shaped project box wired up with a solenoid, LCD display, headphone jack, and other electronics to turn this electronic heart into a complete study tool for heart rhythms. The nurses in [Addie]’s unit love the thing, and it looks like [Addie] might have a real cardiac training tool on here hands here.

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Building a synth on a breadboard

synth

Building an analog synth is a challenge, but with the [Tymkrs] protosynth, it’s easier than ever. It’s a 25-key keyboard attached to a stack of solderless breadboards to make analog synth prototyping a snap.

Earlier, [Tymkrs] acquired a whole bunch of solderless breadboards and decided to put them to use by making a component-level modular synth. The earlier incarnation tied each key on the keyboard to a few wires behind the breadboard and tied them in to a shift register so they could be read with a Propeller dev board loaded up with a Commodore SID emulator. The new version keeps the very clean through-the-back keyboard connector, but this time the [Tymkrs] are adding a few more components that add a sequencer setup and a rotary encoder.

The eventual goal for this really cool breadboard synth is to explore the world of Moogs, Arps, and other analog synths easily on a breadbaord. The [Tymkrs] have already put together a breadboard-compatible low pass and high pass filter. While there’s still a lot of work to be done to make an analog synth a reality, the [Tymkrs] are off to a great start.

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Quadruped walks of four legs, rolls on four treads

tracked-quadruped-robot

This robot doesn’t know if it’s a walker or a tank. It’s the brain-child of [Marc Hamende] who works as a mechanical engineer by day and mad roboticist at night. The best place to find full details is by digging into the long thread he’s been posting to for about six weeks. It will give you a pretty good snapshot of his approach, starting with SolidWorks renderings of the project, and adding in assembled components as he brings the project together.

The mechanism for each foot is fascinating. He milled the white pieces which stack together to encapsulate the motor that runs the treads. These assemblies pivot to bring the metal rod serving as a walking foot in contact with the ground. But they also make it possible to adjust the treads to deal with rough terrain. A Propeller chip drives the device, with an Xbee module to communicate with the controller.

Don’t miss the video after the break. You’ll hear some skidding as it makes turns, but [Marc] plans to add code to adjust motor speed in order to compensate for the inside/outside differential issues. He’s also posted an image album over at Flickr.

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NSL takes their propeller driven car to the drive through

nsl-propeller-driven-land-vehicle

So what’s the first thing you do after completing your propeller driven land tricycle build? Head on over to the Starbucks drive through and see what kind of response you get from the workers. That’s exactly what the guys from North Street Labs did. You can see the response in the clip after the jump.

Having three wheels and being moved by an electric motor with a propeller led to the name TriFly. The build is their entry in The Deconstruction, a build contest which includes other entries like the Beer pouring machine we featured on Monday. Aside from the fun with the final project, NSL’s well-produced video includes a quick trip through the fabrication process. They did a great job making the machine about 40% street legal and it’s obvious they had a blast while doing so.

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Portable gaming console uses SSD1289 and Propeller

building-a-portable-video-game

[Samir] dabbles in hobby electronics and decided to put his skills to the test by building this portable gaming console (Note: this site uses an HTTPS address which cannot be used through Google Tranlator. It does work for the Chrome browser translator). The image above is a screenshot from his Breakout-style game. The paddle at the bottom is controlled with the touchscreen. You move it back and forth to keep the ball from traveling past the bottom edge (it bounces off of the red borders on the sides and top).

The main PCB is larger than the 3.2″ LCD footprint, but [Samir] made sure to include a lot of peripherals to make up for it. The board sports a Parallax Propeller chip to run the games. It interfaces with the SSD1289 screen (this is a cheap and popular choice) but that really eats up a lot of the IO pins. To control the game the touchscreen can be used as we’ve already mentioned. But there are two other options as well. There is an expansion port which uses a shift register (74HC165) to serialize the input. For prototyping this allowed [Samir] to use an Atari joystick. He also rolled a Bluetooth adapter into the project which we would love to see working with a Wii remote. Rounding out the peripherals are an SD card slot, audio jack for sound, and an RTC chip for keeping time.

There are several videos included in the post linked above. After the break we’ve embedded the game-play demo from which this screenshot was taken.

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Watermelon air boat

watermelon-air-boat

We think you’ll turn a few heads in Central Park if you’re driving a water melon around when everyone else is piloting sailboats. This watermelon is both sea worthy and radio controlled thanks to the work which [Starting Electronics] put into it.

We used this image because it shows you what’s inside of the hull, but you don’t want to miss the thing motoring around an above-ground swimming pool in the clip after the break. The hollowed out shell is quite buoyant and has no problem staying afloat and upright with the addition of a propeller. The parts from a remote control airplane kit have been mounted on a wooden scaffold. This provides plenty of thrust with a servo motor moving turning the prop for directional control. There is no dagger board so the craft is a bit slow to respond to turns. But how responsive do you expect a floating melon to be?

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Creating a MIDI synth from a Commodore SID

The Commodore SID was the audio chip in the venerable Commodore 64 and in the 30 years since release has attained classic status and become one of the best ways to get your chiptune on. Designed by famous synthesizer designer [Bob Yannes], it was only a matter of time before we saw a real, homebrew MIDI synth based on the Commodore SID.

Because real SID chips are rare as hen’s teeth nowadays, [Jeff Ledger] built his SID synth around an emulated system running on a Pocket Mini Computer. This very cool microcontroller platform runs on the Parallax Propeller. An emulated SID runs in one of the Propeller’s 8 cores, with the remaining cores kept open for reading MIDI notes and displaying info on a display.

The hardware portion of this build is amazingly simple; just an optoisolater, a few resistors, and a diode connect a MIDI keyboard to the Pocket Mini Computer. The buttons and dials on [Jeff]’s MIDI keyboard control the waveforms, filters, and envelope controls. A very neat setup if we do say so ourselves, and just perfect if you’re needing more chiptunes in your life.

You can check out [Jeff]’s video after the break.

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