This isn't the first LED pocket watch to exist (I saw this one
), I want one of my own, and when I want something, what I really mean is I want to build something. There are some flaws in other designs that I didn't like, so I have my chance to improve upon those flaws.
The top three goals are to look good, user friendly, long lasting.
It is very common to see LED pocket watches that do not have all 60 LEDs for the minute "hand", some have only 12. I really want a clear indication of the current minute with no guessing or estimation involved. So I decided to use 60 LEDs.
I want 60 LEDs for the second "hand", and some of the other designs do not feature a second "hand" at all. As the seconds change, it creates motion, which gives the viewer a feeling of confidence and pace. You will feel confident that the watch is working, because you can visually see each second tick away. Plus, it will look prettier.
There are 12 LEDs for the hour "hand", not 60. Although following the behaviour of an analog clock might sound good, it makes it a bit slower to visually interpolate the current hour.
I explicitly chose not to use bicolor or tricolor LEDs. I want three rings because the different radiuses helps me distinguish between the different "hands" faster.
Right now I check the time using my phone, I'm sure a lot of you do too. So I decided I wanted it to have the size that fits comfortably in my hand, just like my phone, and I wanted a single button to activate it, just like my phone.
I wanted this to be something I use daily, it must be durable. Most of the time it will be in my pocket. A casing is required to protect the circuitry from junk inside my pocket. The casing also has a hole, so I can attach it to a chain.
Nobody likes replacing batteries, especially when it is stuck inside a case. So I decided to use a rechargable battery. The easiest battery charging method today is probably by using USB, all you need is a cord and a USB port.
The buzzer and motor feature are basically just fancy additions because I can do it. I'm not limited on cost, and they will physically fit in the design, so why not?
I made one that is black and green because green is the cheapest PCB color and I have a preference for black. The purple edition is because OSH Park makes purple PCBs, I wanted a case to match the color, why not make two and see if I like it.
As I am coming up with my goals, I also have to consider the materials and equipment I have access to. PCB, laser cutting, and 3D printing services can be found online and I am already very familiar with all three of these techniques.