Wordclock

At the end of 2014, I wanted to build a word clock, as a gift. I started looking around for parts and when I found a square picture frame in a local shop, I decided to built my clock in it :) The base:

The base: a square photo frame found in a local shop

After taking measurements and creating a word order (taken from the QlockTwo), I figured I would make a board with baffles to light a letter mask. Initially, I created these baffles by cutting pieces of MDF by hand, but the result was appalling. Thus I created a drawing in Inkscape and cut it at the FabLab of Leuven.

First attempt at glueing the baffles for the LEDs. Later I went to a fablab to lasercut it from MDF.

Then the task of soldering all the white LEDs had to be done... I opted to control each group of LEDs independently. There would be around 32 groups of LEDs. Each group is driven by an ULN2003 Darlington array output, which in turn connects to a bunch of CD4094 shift registers. I consider this quite un-elegant, as it means that each group of LEDs needs a specific current limiting resistor, so that all groups would have the same brightness. But time was running out...

Eventually all the LEDs are wired to a big connector that plugs into the control board:

Almost done. Because it had to be done quick, the LEDs are soldered in parallel groups. Depending on the size of each group, a different resistor value is required to achieve equal brightness between the groups.

Soldered the control board and the LED resistors. It uses an Arduino Nano and a DS3231 battery backed realtime clock

In front of the LEDs, I put the mask with the word design. On one instructable I stumbled upon, they used an overhead sheet for laserprinters. By layering 4 or 5 of these, I was able to eliminate the light bleeding. However, since I used clear white LEDs, it was difficult to see the letters from an angle. This was simply solved by adding a sheet of white paper :)

By layering a number of laserprinter overhead sheets, I got a nice mask for the LEDs

And I added two buttons to be able to set the time and adjust the brightness in steps.

Some creative glueing and cutting to connect the original picture frame's 'locks' and stand

Finally, the result:

After a while, the Arduino Nano broke. It was a cheap clone, so that did not surprise me. I had some Nano's before that were powered by USB continuously, and for one of them, the USB-serial chip died, and the other had a malfunctioning diode, keeping the uC in a sort of brownout state. Eventually, I removed the USB serial chip and programmed it with another Arduino.

Another point is the soldering itself. As you can see above, I bended the legs of each LED to interconnect them, but after some time, the solder cracks where the LEDs' pins join. No solution found yet for this.