[Adam] wanted a stereo that could stand up to rain and keep sand out. He ended up building this beach stereo out of a cooler. The cooler’s already made to be water tight. He cut holes in the front and back for marine speakers and added a water-tight bezel and cover for the controls on the deck. Inside you’ll find a marine battery to power the unit. Now he and his friends can rock-out even in poor weather thanks to this portable and rugged unit.
We’ve seen a glut of time-keeping projects lately. We guess time was the original motivator for technology so we’re okay with it (but we’re not calling ourselves Clockaday quite yet). This clock, or more appropriately this timer, is a homemade hourglass that [Andrei] put together. The finished look is simple but he put some real time into its production.
The glass portion is a combination of two wine glasses. He removed the stems, ground the bottoms flat, then drilled holes to allow the sand to pass. He used plumbers putty around the top of the upturned reservoir to create a temporary bowl of water which cooled the glass during drilling. This prevented cracking by keeping the friction generated heat at bay. Working with the glass took a total of around five hours.
To assemble, he epoxied the two wine glasses together, routed out a ring in the wood bases for the lips, and used dowels to connect the two ends. [Andrei] concluded that the gentle slope at the bottom of the wine glasses is not the ideal shape as some sand can get stuck in them. Perhaps champagne flutes for his next build? At any rate, we think it’s a unique, non-automated hourglass build.
[Peter] thought of a creative, way to generate random entropy for under $100.
The USB Hourglass combines a sand timer with a rotating mechanism and an optical beam through the center of the timer to observe the falling sand. The amount of light reaching a detector is digitized at frequent intervals and processed by a microcontroller to determine when to rotate the hourglass. The digitized light levels are also sent by USB to a host PC where they can be used as a source of random entropy. Power is supplied over the USB cable.
With the USB Hourglass, the user can look at the sand falling through the center of the hourglass and monitor the randomness in the USB output data. And one can read the code line-by-line, compile it, and upload it to the microcontroller using only open-source and widely supported tools.