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How to build a ping-pong ball display

If you’ve been lusting after your own glowing display we’re here to help by sharing some simple building techniques that will result in an interesting project like the one you see above. This is a super-accurate clock That uses ping-pong balls as diffusers for LEDs, but with a little know-how you can turn this into a full marquee display. Join me after break where I’ll share the details of the project and give you everything you need to know to build your own.

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Color clock makes telling time impossible

[Bogdan] set out to build the all-too-familiar binary clock. But, he didn’t want to be ordinary, and set the goal of making the clock as hard to read as possible. What he ended up with is a clock that is almost impossible to read correctly.
He’s using colors to tell the time. We immediately thought this might make use of resistor codes as the display but it doesn’t. Red shows the hours, green for minutes, and blue for seconds. Now stack all of them on top of each other in binary and you’ve got the time. That means you’ve got to know all of your color combinations, plus read the binary value correctly, to decipher the time. Add to that the display changing every second and we’re in trouble.
Aside from the user difficulty level, this is a really clean build. It uses an ATmega8535 in conjunction with our favorite DS3232 RTC chip. The etched board is nice and clean, making for an aesthetically pleasing clock.

Clock hides time until you’re in close proximity

[Alan] is branching out beyond the Arduino with this clock. He’s still using the same code but built this board around an ATmega328 and the components he needed, saving his Arduino board for further development. The concept uses a character display housed in an old iPod Touch case. The build relies on an infrared sensor to actuate the LCD backlight. The closer your hand is the brighter the light.

The Maxim DS3232 RTC chip keeps time in this application. We’ve seen this little marvel used before, popular because it uses temperature compensation to maintain accuracy. If you’re interested in this part, check out the library file that [Alan] wrote for it.

Binary clock uses DS3232 RTC

[Kenneth Finnegan] quenches our clock-a-day compulsion with his Arduino based binary timepiece. The clock uses a 5×7 LED matrix as a display and shows month, day, and time. He sourced a DS3232 real-time clock which automatically compensates for temperature to achieve very accurate time keeping. We like the super-cap circuit he added to keep the RTC running if the power is cut.

Is an Arduino overkill here? Well, the code is certainly not filling the 16k available on the ATmega168. At $4.32, the $1-2 you could save by using a lower-grade chip is not worth having to rewrite the code developed during prototyping. [Kenneth] also mentions that these projects usually only hang around for a few weeks before they’re re-purposed for the next endeavor.

Take a look at [Kenneth's] superb hardware walk through in the video after the break.  If you’re a fan of clean breadboarding, he’s also made a time-lapse of the circuit building process.

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