An array of LEDs randomly changes patterns every 10 seconds or so. To read the time, simply count the number of dots per digit. The main pic shows the time, 22:11. Different colours are assigned to different digits, red-10hours, amber-hours, green-10minutes, blue-minutes. Using 3mm superbrights means the clock can be read daytime or night (though it'd be washed out in full sunlight).
Having a random pattern is a lot less distracting than having numeric digits staring at you...this would also be a great project for adding to the front or size panels of a PC mod.
Step 1: Overview
This project was inspired from the TixClock device I saw being advertised at ThinkGeek. That was a little large for my application, I wanted a clock above my DVD because it didn't display the time when playing a DVD.
The design is based around the case, a low profile 'display' case from Jaycar Electronics (www.jaycar.com.au) catalog number HB6083. If you want to put this clock in another case, you'll have to modify the PCB layout.
A zip file with sourcecode, pcb files in EagleCad format and some pics is included in the project.
Some tracks are a bit narrow and have very little clearance. I built this using press-n-peel film, so it can be done....just take a little care not to smudge things and carefully check the result, scratching out any blurred tracks that might be touching another.
The PCB is designed for two layers, however I constructed this on a single sided board to save effort. There are only a few tracks on top, and these can be dealt with by using hookup wire. Note the picture is a little different from the PCB design in the zip file. The changes were connecting the enable pins of the 74hc154 chips directly to ground and an extra diode to step down the voltage across the supercap to make it closer to the 3.3V required by the RTC chip.
Some handy hints when doing double sided board using single layers is to:
- do as much trackwork on the bottom side as possible
- when laying a track on top, always take it to a via, rather than connecting the top layer track directly to a component.
- when using press-n-peel, print out the silkscreen (in reverse) and iron this to the PCB after drilling and etching. This not only gives you component placement, but if you print the top tracks out as well it is an easy guide for hookup wire. Note the black lines in the PCB below....these would be where the top layer tracks would be.