I don't know what it is about clocks and watches, but it seems that every second projects is one form of the two. This project follows along in the footsteps too. I have made smaller clocks before, but nothing of the scale of a typical wall clock. This is due mainly to the high price of fabricating one off large PCBs.
I wanted to create something large, not too big. I also wanted to keep the cost down. I managed to solve these problems by making various design choices, which will be covered in detail in the following steps.
I got some initial inspiration from adafruits 12 pixel neopixel ring, and now I notice that they sell a 60 pixel version which wasn't available back when I designed this, but comes as 4 segments to create a full ring. This would be an easy way to create a similar clock, without the need for making PCBs and soldering LEDs and small SMD parts.
I showed my design off over at the 43oh forums at the first prototype, the users there are great. They offered hints and design advice, aswell as helping source cheaper LEDs and PCBs, by buying in bulk via a group buy. If you have a projects that you are working on you should think about taking the time to display it somewhere online. Another great reason, since writing is a creative process, it can definitely help you process ideas and thoughts if you ever get stuck on a project.
Please note, I am writing this more as a project log rather than a tutorial, Basically because I will only make one of these following the steps outlined here exactly, and I know that if I make it again it will be different, and different again after that. Files for the PCBs and BOMs will be provided at the end, I would encourage you to get the PCBs fabricated and solder up a ring if you think you are up for it, I'd love to see your own artistic spin on it. :D
The design idea was to create a ring, since a few of the cheap PCB manufactures will send you 5 or 10 pieces of your single design, I figured it would be pointless to buy a 20cmx20cm PCB, and then waste 80% of it. Prototyping with boards that large is much more expensive than small 5cm squared boards. Not to mention that I would have paid for 5 pieces, and would only be using 1.
The solution was to create a small arched segment, that would be identical, and could be daisy-chained together. Initial designs involved a data/clock/latch/power data connection between boards. each board would then need a serial shift register and some driving electronics to drive the LEDs, this solution would work perfectly fine, except it would only provide a binary output to the LEDs. I wanted more than colours.
Moving on to another thought, LED drivers. This would have basically been a similar electronics setup to the equinox clock. Which I actually took some inspiration from. This would have used up alot of space on the PCBs and would have actually increased the total cost quite a lot.