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Published on September 28th 2015.
About two months before my girlfriend turned 18 years old, the idea to build her an awesome gift came to my mind. It couldn’t be something simple of course, but instead, something that is pretty, unique and valuable. After a few days of searching around, I came across this project, and it was exactly what I was looking for. Thanks to the detailed build log, I could immediately start designing and building the clock. In the end it was a huge amount of work, but the result is great! Sadly, we broke up before she turned 18, so I never got the chance to give her this clock. Oh well.
Apart from telling the time, this word clock also displays a special birthday message on her birthday in rainbow colours, which makes for an awesome addition.
The clock displays time as words, and minutes in multiples of five. 15:02 (or 03:02) is displayed as “Het is drie uur” (“It is three o’clock”). The whole thing has a height and width of 25 centimeters and is around 5 centimeters thick.
Once a year, the birthday words will light up and the text “Fijne verjaardag Anouk” will be displayed in fancy rainbow colours. “Fijne verjaardag” means “Happy Birthday” in Dutch and, you guessed it, her name’s Anouk.
Here’s a quick translation chart! As you can see, there are quite a lot of similarities.
There are two illuminated pushbuttons on the right side of the clock which can be used to adjust the time. One button adds five minutes while the other subtracts five minutes. Pressing both buttons at the same time activates a special mode!
Design company Biegert & Funk sells a similar clock for over €1000, and that doesn’t even get you a fancy birthday message. I spent about €100 on parts for this clock, but it did cost me over a hundred hours to complete it.
The front plate of the clock is made of 3 mm thick birch plywood which was cut out with a laser cutter. I had the cutting work done by the Dutch company Snijlab. They are an awesome company and provided great support.
It’s hard to see how beautiful the rainbow effect of the birthday message really is. Especially in the dark!
My first step was to test the circuit and the components needed for the project. I started with a breadboard and some simple LEDs which I controlled using an Arduino Leonardo. For the clock as a whole, I used the following electronic components:
- Atmel ATmega328P-PU microcontroller;
- 3 ULN2003A darlington transistor arrays;
- 3 HCF4094BEY shift registers;
- LM7805 5V voltage regulator;
- ~100 white diffuse LEDs;
- ~100 470 ohm resistors;
- 15 WS2812B RGB-leds;
- DS3231 Real-Time-Clock (RTC) module
- A truckload of soldering tin and wires;
- Several other types of components, resistors and capacitors.
I wanted to build and connect all the electronics together as neat as possible. To achieve that, I needed to reduce the amount of loose wires to a minimum. I did this by soldering together this circuit board which neatly packs together most of the electronics. In the bottom right there are four inputs, and all the outputs for the LEDs which light up the clock are on the top.
The bottom side of the board doesn’t look as good as the top, but everything works, so I’m happy.
To finish the circuit board, I soldered the last few wires to the top of the board and then put in the IC’s (Integrated Circuits) into their sockets.
This circuit scheme shows how all components are connected together. My original plan was to use a normal Arduino instead of a ATmega328 chip to control the clock, but I later decided it would be better to use an ATmega328 chip to save money as well as space.
The ATmega328-ICs I had had no bootloader burned onto them yet, so I had to do that first. You’ll need an Arduino Uno and a few components.
I then soldered together the ‘standalone Arduino’. The LM7805 voltage regulator is placed on the top left of the circuit board. It converts the 12V input voltage to 5V. The LM7805 gets quite hot for some reason, but apart from that the system is reliable. The soldering work for the electronics that control the clock is now done.
For the front of the clock, it was necessary to find a font that meets several requirements: first off, no letters or parts of letters should fall away during the process of laser cutting, so I needed a so-called stencil font. For example: with a normal font, the inner part of the letter ‘O’ would drop away when laser cutting, which is obviously not what I want. Secondly, every single letter should be of the same height and width to form an even grid. I came to the conclusion that such a font simply does not exist, so I made my own custom font in Adobe Illustrator (Based on a normal monospaced font) and designed the front plate using that.
After completing the Illustrator file, I sent it to Snijlab to be lasercut. One week later, the finished parts were delivered to my house.
I had some more stuff cut out since there was free space on the wooden plate, so I had to cut the front panel to size. It turns out a scrollsaw is the perfect tool for the job.
Aaand done. I needed another piece of wood of the same dimensions so I cut that out too. The LEDs that will light up the clock will be mounted in this plate. I didn’t use the same 3mm thick birch plywood for this, but instead I used poplar plywood with a thickness of 4mm, because it was a bit cheaper.
I drilled holes where the white LEDs will go. The holes are of the same diameter as the LEDs which means they’ll fit in snugly.
I put in all the LEDs and secured them with glue gun glue. I left the holes for the RGB birthday LEDs empty for now.
Each LED has it own 470 ohm resistor. This is to prevent that words of different lengths have different brightnesses. After a few hours worth of soldering, it was all done. I then soldered jumper wires to every group of LEDs. These will be connected to the clock controller later.
Testing the RGB LEDs using an Arduino. They give off a nice glow!
I mounted the strips of birthday LEDs to the plate using tape. The Arduino can control each of the LEDs on the strip individually. The colour communication requires only one wire for all LEDs.
To make sure the light is spread evenly, a piece of diffuse translucent acrylic is glued to the back of the front plate behind each word. The diffuse LEDs combined with the acrylic give the words a soft glow when they light up.
Quick check to see how the light passes through the acrylic. It turns out the transmission and dispersion of light is just right.
The hardest part of the project is to prevent the leaking of light between different words. When the seal isn’t close to perfect, words or parts of words may be lit up unintentionally, which looks bad. I used small wooden strips which I glued to the front plate to make sure everything seals well.
A bit later all the wooden strips are glued to the board.
To complete the front part of the clock, the part with all the LEDs in it had to be joined with the lasercut front plate. To make sure this seal was light-proof too, I put pieces of blu-tack on the wooden strips and I then ‘sandwiched’ the two parts together.
Testing! It looks like the seal is pretty good. With this done, the part that has to do with all the lighting is complete.
In the above picture, three grooves are being cut in a piece of hardwood which will become the frame. Both the front and back part of the clock will slide in along these grooves.
For the frame, I needed four pieces of wood of equal length. I cut the ends on an angle of 45 degrees using a miter saw so that the four parts can form a square frame together.
The first two grooves are for the lighting part of the clock while the third one is for the plate that will cover the back side of the clock.
A quick check to see if all the frame parts actually fit together. I had to use some sandpaper to make everything fit.
Two holes have to be drilled for the illuminated buttons. Doing some measuring work…
I first drilled a small hole with a 3mm drill bit, and then made the hole bigger with a special 16mm drill bit.
I didn’t want to use glue to put the frame together (and that would be less strong anyway) so I used two corner brackets instead.
After assembly of the three pieces, this is what the frame looks like. The front and back plates of the clock slide in through the open side of the frame.
Time to mount the controller and connect all the wires. I covered the bottom side of the controller circuit with tape to prevent it from short-circuiting with the leads of the LEDs underneath.
Little errors like this one are super annoying. Because of this broken solder joint, most of the words wouldn’t light up and I only found the problem after a solid hour of troubleshooting.
Testing, testing and some more testing.
I mounted the front part of the clock in the frame and wired up the buttons. Everything is working well so far!
Almost done! The ATmega328-microprocessor (middle) and the DS3231 RTC (right) are now mounted and wired up too. These are also covered with blue electrical tape to prevent short-circuiting. I also secured the electronics to the wood using this tape because I couldn’t come up with a better way to do it.
Close-up of the button connections. I isolated all wires and solder joints using heatshrink tube.
Here you can see the back side of the clock. I put in a connector for a standard DC barrel jack which are often found on standard 12V adapters. This way, I can transport the clock without its power supply cable.
There she goes. By the way, you can see I added in a 1000uF capacitor on the 5V input of the controller. It is always a good idea to do this.
Here you can see the bottom side of the clock. The fourth piece of the frame completes the clock and is secured by one screw on each end. I drilled a little hole before putting in the screw to prevent the wood from splitting when putting in the screws.
Because these screws are situated on the bottom of the clock, it is important for them to sit flush with bottom of the clock itself to prevent it from wobbling around. By using a special drill bit, the screws are countersunk into the wood.
As you might be able to see, the frame isn’t perfectly straight and square, but this is no major problem. You can barely see it.
This completes the build of the birthday word clock!
Thank you for reading! You can send any questions, remarks or feedback here. I’ll try to answer everything as soon as possible!
You can download the design files (Illustrator) here.