Last November, I went to an art gallery and came across a pretty design clock that would have found its place in my living room.
After seeing its price, I felt of passing out! When I came back to myself, I decided to build it myself (in better).
I wish to present you a small project that has occupied me lately: The reproduction of a design clock.
This clock is a square about 39cm, which can be placed on furniture or hung on a wall.
The facade consists of cleverly arranged letters that will give the time.
The principle is simple. The clock is composed of a matrix of characters that will illuminate to write the time it is. For example "it is eight to ten minutes" or "it is midnight and a half".
The time is thus given in 5-minute increments. Four luminous points at each corner of the clock will successively light up to give the hour to the minute in that slice.
So, if 3 corners are lit when the text displays "it is two hours ten", it will be understood "it is 2 hours 10 + 3 minutes".
Anyway, who cares to have the hour by the minute...
This clock is judicious because it has a brightness sensor that will adapt brightness according to the ambient light. This will allow you not to be bother by the light in the middle of the night :)
Moreover, the facade (here in rusty steel) is magnetized to the frame. It is easy to replace it with a facade with another style or a language...
Step 1: Principle
In the Spirit, there is nothing technically very complicated. A lot of LEDs are driven by a microcontroller with a time counting system and powered by 220VAC. All in a nice wooden and iron box :)
So this product should not cost the price asked by the reseller of the original model and my little geek side sees the opportunity to add many cool features like:
- A WiFi connection for time synchronization and configuration from a web interface.
- A matrix of RGB leds to change the color of each letter.
- Full of fun display modes I could develop over time.
I had several objectives for this project:
- Build a stylish and useful connected (IoT) object.
- Bury myself in technique to avoid losing my touch.
- Keep myself busy during the long winter evenings.
During this post, I will explain each stage of the project in order to keep track of it and to allow you to build (and to improve) the clock.
Step 2: Stage 1: Architecture and Search for Technical Solutions
Like any technical realization, I start to think about the different ways at my disposal to achieve this object. All the configurations ‘ve got advantages and disadvantages and I had to manage with all f this to find a functional, reliable, inexpensive and within the scope of my competences result. Especially since this clock is the sum of skills in mechanics, electronics and software development.
I began by the definition of the expected functions of the clock and started to search for electronic bricks to realize them.
I voluntarily go over the details of this research to present directly the selected components. But it is important to know that this was the longest phase of this project. I didn’t want to buy any component that will ultimately end up in the bin. Moreover, I chose to voluntarily simplify as much as possible the domains that I master the least by favoring solutions already integrated.
Finally, I kept an eye on the project expenses.
On the mechanical part, it is important to think about how the various electronic components will be arranged, starting with the ribbon of led.
Each led should illuminate only one letter. A diffuser must be provided for each of them. In addition, the spacing between the letters also depends on their size and the spacing of the LEDs on the ribbon.
I looked for suitable and inexpensive led reflectors (because we need 114 of them).
The full nomenclature of the clock is given on my website www.psykokwak.com
Step 3: Stage 2: Mechanical Design 1/2
I began to draw in CAD the front of the clock with Solidworks. This one is composed of 3 layers:
- The reflector support that will be attached to the frame (MY_001).
- A sheet of tracing paper to diffuse the light emitted by each led.
- The steel facade with letters (MY_002).
Then the wooden frame is composed of 4 edges, 4 brackets and 4 supports. The brackets and supports are used to hold the facade.
Once the design of these parts completed, it is necessary to realize the different drawings that will be sent to the different subcontractors to produce them.
The drawings are available for download my website www.psykokwak.com
Step 4: Stage 2: Mechanical Design 2/2
Once I put together the frame, I received the steel façade and I started the treatment to give it the desired rusty effect.
Be careful to do this operation in a ventilated place, and to use appropriate protections.
You can see below the evolution of the facade during the operation left (steel) to the right (steel after the treatment and application of a fixing agent)
Step 5: Stage 3: Electronic Design
The electronic part is done in 3 steps:
- Test and validation of each function on test plate.
- Design of the electronic card (in reality there are two).
- Realization of the final electronic cards.
I voluntarily pass on the first step and go straight to the 2nd.
I am not an electronics technician and I can not make a little evolved board design and I do not talk about routing. So, for this time, I made the circuit by hand on an experimental plate.
The brightness sensor will be installed behind the symbol of the bell on the first electronic board.
The second electronic board is the one where the microcontroller and the other components are found.
Then I made the circuits:
I used a thermal camera to monitor the maximum consumption of the circuit and the temperature of the cables and components. I realized that my power supply 5V @ 5A was just enough.
Step 6: Stage 4: Assembly
The next step is to put together the electronics and the frame.
I glued all the reflectors on the support (MY_001) and then I cut the ribbon of led to make each of them match with their diffuser.
Given the spacing between the LEDs and the size of the diffusers, I planned to place the led ribbon diagonally.
Each portion of the led is connected to the others by wires welded together. And each led is glued on its diffuser with glue gun.
Be careful to respect the same order to glue the led.
Then I put the facade in the frame and place the various electronic circuits inside it.
Step 7: Step 5: Software Programming
The small card "NodeMCU" is based on a very small microcontroller called ESP8266. It has a first advantage, it cost only 2€.
Moreover, the great interest of the open-source community for this small processor, it is easy to find a lot of software tools and bricks in online libraries.
As a result, this card is fully supported by the Arduino environment. Arduino regulars will not be disoriented :)
The compiled program would be display at the end of this article. You only have to upload it to the processor to be able to use the clock.
When the clock starts, it loads its configuration and connects to the registered Wi-Fi hotspot. If it doesn’t find it or if it does not have a saved configuration, it uses itself as an access point.
In this case, from a computer or telephone, connected to your wifi network (not secure), enter in the browser the following url: http://192.168.1.1/.
From there, you can configure the wifi settings of the clock your wifi network. It will then automatically set itself from an NTP server.
Now, it is possible to update the program directly from the web interface. It is useful to quickly install updates that contain new animations :)
Step 8: Findings
This project occupied my evenings for 3 months and cost me about 150€. I estimate the time spent on this project around a hundred hours of work.
I put all the elements at the disposal of the community. You can now make your own one, if your heart tells you.
I am generally satisfied with the result. However, there are a few things to improve for the next version:
- The magnets are not powerful enough to hold the steel plate properly.
- The facade is a bit too big. It is necessary to reduce the size of the facade a bit to let a slack.
- The light sensor is not sensitive enough in low light, making the adaptation of the power of the LED lighting ineffective.
- The temperature sensor of the RTC is too close to the transformer. As a result it gives a higher ambient temperature than it is in reality.
- The diameter of the reflector is not large enough to fully illuminate the tail of the letter "Q".
- It can be interesting to replace the useless letters of the matrix with the missing letters in order to have complete alphabet.
All information and file (schematics, firmware, ...) are available on my website : www.psykokwak.com