12ft GPS Wall Clock

Posted on Feb 4, 2014

We discussed creating a 6` tall alarm clock - authentic down to the Timex face plate. While this may sound like a silly idea to begin with, it quickly became obvious just how difficult it would be to build at that scale so the project was scuttled. Recently, I came across a source for pre-package LED light bars that rejuvenated

12ft GPS Wall Clock
Click here to download the full size of the above Circuit.

my need for a big clock. Why not So here is the little project that grew to 12 feet. We added a GPS receiver so now we have a 12` clock that sets itself, displays hours/minutes/seconds, and is accurate to 100ns. Beat that bed side alarm! These light bars, as I like to call them, use three LEDs and run on 12V. Why use them They come pre-packaged with current limiting resistors and nice plastic carriers. This made it easy to create arrays of a large number of super-bright LEDs, without all the hassle and labor of creating our own custom configuration. Each stick uses about 30mA @ 12V. This is actually pretty good considering how bright they are. 30mA is a fraction of what an equivalent neon tube would pull. It started out as just hours and minutes. Then it was obvious we needed a colon. Then the seconds were so cool that we just had to have them, so in the end, it was two colons and 6 digits. In all: 2. 76Amps! At 12V is ~33Watt power supply. This is not small by any means. Come to mention it - perhaps we could use an ATX power supply. Hmm. Maybe later. At this time, we are using a basic variable bench power supply from Mastech, the HY1803D. With an 18V 3A max output, it handles the 12V @ 3A requirement easily. Originally I was going to simply screw the light bars onto the wall in a 7-segment digit configuration. That`s where things turned south. The LED bars are fabulous! But the LED intensity is so high, it`s painful to...

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