These Sands Of Time Literally Keep Time

Hour glasses have long been a way to indicate time with sand, but the one-hour resolution isn’t the best. [Erich] decided he would be do better and made a clock that actually wrote the time in the sand. We’ve seen this before with writing time on a dry erase board with an arm that first erases the previous time and then uses a dry erase marker to write the next time. [Erich]’s also uses an arm to write the time, using the tip of a sea shell, but he erases the time by vibrating the sandbox, something that took much experimentation to get right.

To do the actual vibrating he used a Seeed Studio vibration motor which has a permanent magnet coreless DC motor. Interestingly he first tried with a rectangular sandbox but that resulted in hills and valleys, so he switched to a round one instead. Different frequencies shifted the sand around in different ways, some moving it to the sides and even out of the sandbox, but trial and error uncovered the right frequency, duration, and granular medium. He experimented with different sands, including litter for small animals, and found that a powder sand with small, round grains works best.

Four white LEDs not only add to the nice ambience but make the writing more visible by creating shadows. The shells also cleverly serve double duty, both for appearance and for hiding things. Shells cause the arms to be practically invisible until they move (well worth viewing the video below), but the power switch and two hooks for lifting the clock out of the box are also covered by shells. And best of all, the tip that writes in the sand is a shell. There’s plenty more to admire about the cleverness and workmanship of this one.

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‘Vortex-drive’ for underwater ROV propulsion

This is [Lee von Kraus’] new experimental propulsion system for an underwater ROV. He developed the concept when considering how one might adapt the Bristlebot, which uses vibration to shimmy across a solid surface, for use under water.

As with its dry-land relative, this technique uses a tiny pager motor. The device is designed to vibrate when the motor spins, thanks to an off-center weight attached to the spindle. [Lee’s] first experiment was to shove the motor in a centrifuge tube and give it an underwater whirl. He could see waves emanating from the motor and travelling outward, but the thing didn’t go anywhere. What he needed were some toothbrush bristles. He started thinking about how those bristles actually work. They allow the device to move in one direction more easily than in another. The aquatic equivalent of this is an angled platform that has more drag in one direction. He grabbed a bendy straw, using the flexible portion to provide the needed surface.

Check out the demo video after the break. He hasn’t got it connected to a vessel, but there is definitely movement.

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The most surprising game of Simon you’ve every played

How does one take a game of Simon and make it extremely awesome? The folks at the North Street Labs — a Hackerspace in Portsmouth, Virginia — have found the secret and it’s all in the execution. They turned this chair-desk into a coin-operated Simon game that hides a huge surprise.

We suppose you should be able to guess the secret. Most coin-operated sidewalk attractions are rides, and so is this. As their Red Bull Creation entry the team built a base for the desk around a 2000 Watt floor buffer. These are the kind of things that you’d see a janitor in the 1980’s using to polish the tiles of your middle-school.  This one just happens to shake the bejesus out of a player who makes a mistake. To help suck you into the game this won’t happen right away. You have to make it past at least four rounds before making the mistake.

The rest of the game is as expected. The playing area is nicely milled from a piece of wood with acrylic windows serving as the buttons. Apparently the biggest problem with that part of the build is finding a way to hold everything together despite the intense vibrations. See for yourself in the clip after the break.

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You can keep your mints safe; we have the technology

After having his mints disappear for quite some time [Quinn Dunki] came up with an idea to get back a the fresh-breath thieves. A bit of circuit design, parts scavenging, and free-form construction led to the creation of his mint-tin burglar system.

Here’s how it works. Flip the on/off switch in the base of the mint tin before you head off for lunch or a coffee break. When the foul-mouthed pilferer hits up your stash they’ll get what they were looking for at first. But by opening the tin they tripped a timer circuit that will send the mints vibrating across the table soon after having been opened.

The breadboard above holds the prototype timer circuit, built around or friend the 555 timer. The vibration motor from a cellphone is a perfect choice for this hack as it’s very small and is just waiting to run from a low-voltage source. We especially liked the use of the cells from inside a 9V battery as a power source and the compact assembly that manages to fit inside the mint container.

NES controller gets a rumble pak

Add some feedback to an original NES controller by making it vibrate. This feature is often known as Rumble Pak, a controller add-on for the Nintendo 64 which vibrated as a game feature. This version adds a small DC motor (in the upper right) with a screw soldered off-center to the motor shaft.

[Andy Goetz] and his friend built this as a robot controller, taking advantage of the latch and clock pins. Normally, nothing happens while both pins are held high, a signal that they easily patched into using an AND gate. This is actually a neat find, as the addition of an internal microcontroller could add bi-directional communication when the latch is high and the clock is strobed.

Plants as speakers

You can make pretty much anything a speaker by vibrating it. Japanese engineer, [Keiji Koga], has been working for many years to perfect his plant based sound transmission system. The voice coil is at the bottom of the plant container and transfers sound up the stalk to the leaves. It’s and interesting idea, but we can’t imagine it sounds much better than vibrating a rigid surface.

[via io9]