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sun:time is my project to combine ancient time measurement with todays technology.
The Idea
Teaching physics to my students I am always fascinated how in ancient times people like Galileo Galilei, James Newton or Thomas Edison were able to progress with only simple tools. One of these tools is the sundial especially pocket sundials or diptych sundials. They were among the first portable watches. My first idea was to create a digital sundial. On the dial 12 LDR sensors would register the position of the shadow. A microcomputer would read the sensors and calculate the current time as accurate as possible.
In autumn and winter bright sunshine is rare, so Dubbie Dubbie came up with the idea to create a moon dial and jc2048 suggested to invert the project and simulate with leds the suns position depending on the actual time.
Thinking about it the following possibilities seem interesting:
- digitally read the time and display it
- simulate the suns position
- add an autocalibration method using a compass module, allowing users not to point precisely towards south
- create a heliochronometer adjusting automatically the scale depending on the date and position.
Inspiration
The more research work I did on sundials, the more versions I discovered. Specially the Nomos Sundial ring Diptych Dial grabbed my attention.
| The Nomos Sundial Ring | The Diptych Dial |
|---|---|
First drafts
I did some simple drawings of my ideas.
| {gallery} sun:time drafts |
|---|
A sundial with a small stick and a display. |
A ring sundial with a display. |
A small sundial with a foldable sun simulator |
Which microcomputer to use?
All ideas somehow rely on positioning the dial towards a certain position. As microcomputer the micro:bit would make sense with it’s built-in compass. Why not use it as my microcomputer. I tried to figure out the advantages and disadvantages of several microcomputers.
| Microcomputer | micro:bit | Arduino nano | Raspberry Pi zero |
|---|---|---|---|
| Compass |  |  | |
| Display | | | |
| ADC pins | 6 | 8 | 8 |
| Digital output pins | 11 | 14 | 26 |
| I2C port | | | |
| Programming language | microPython | C | Python |
| Size | 43 mm × 52 mm x 4mm | 18 mm x 45 mm x 5 mm | 30 mmm x 65 mm x 5mm |
If you wanna know more about sundials
Here is a list of websites I discovered when researching for the sun:time