A digital watch in an analog case

Description

This past summer I started building a watch. My idea was to combine a simple digital watch display with a nice watch case. Though it was more involved than I anticipated, it's finally fairly complete!

The toughest challenge with this watch was finding a way to use the traditional rotating crown to set the digital time on the watch. After a great deal of experimenting, I attached a magnetic rotation sensor to the PCB and a magnet to the stem (the metal rod extending from the crown), which made it possible to digitize the rotation of the crown.

The sensor is mounted perpendicular to the PCB, using a tiny second PCB that fits into a slot on the main board. This piece can be printed along with the primary circuit board thanks to existing slot in the PCB required for the watch stem. I document the development process and add many more goodies here: http://joesul.li/van/watch/

Discussions

Alekyakoi wrote 02/02/2020 at 04:39

That is really nice. I am interested which casing did you use?

Also for the magnetic sensor, you can find xyz sensors by infineon or melexis that does not require to be faced to the magnet, it would be easier as you wont need an 90angle PCB ;)

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Joe Sullivan wrote 02/02/2020 at 16:57

Thank you! The case is this: http://www.ofrei.com/page523.html

I did look at those manufacturers, and just took another look. I see some reference to sensing fields that are parallel, but all diagrams related to rotation I have seen for those manufacturers have the field orthogonal to the chip. I’m not expert at this - could you point out what language to look for among the melexis chips linked below?

https://www.mouser.com/Sensors/Motion-Position-Sensors/Board-Mount-Motion-Position-Sensors/_/N-6g7qp?P=1y8oaxt&Keyword=melexis&FS=True

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Alekyakoi wrote 02/07/2020 at 19:15

Thank you for the link.

You could use the TLE493

See the figure 2 YZ config:

https://www.infineon.com/dgdl/Infineon-3D_Magnetic_Sensor_for_Angle_Measurements-AN-v01_10-AN-v01_01-EN.pdf?fileId=5546d46265f064ff01665a3d22f055e3

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msegev wrote 01/27/2020 at 03:25

Looks awesome!

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A digital watch in an analog case

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