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Force Key

Force key image

GitHub Repo
25/11/2024

Description​

The Force Key solid-state morse paddle key, which, as the name implies, uses force senors (load cells) to detect the user's input. It is designed to work in single-lever mode or twin-lever mode.
The output is a standard 3.5mm stereo jack, which can be connected to any morse keyer or transceiver.

Features​

  • Single-lever or twin-lever mode, or both at the same time
  • Adjustable sensitivity in code
  • TRS 3.5mm stereo jack output (tip = dot, ring = dash, sleeve = ground)
  • Li-Ion battery powered
  • USB-C port for charging
  • Uses cheap Puya microcontroller

Hardware​

The HX711 has to be modded to output data at 80Hz rate, which is done by lifting pin 15 and bridging it to pin 16 :
HX711 mod

Inspiration​

The Force key is inspired by the Solid State Paddle by 9A5N, which is a beautiful product; but because of my student budget, I decided to make my own version.
It was a nice challenge as I wanted to use the Puya PY32F002A microcontroller, which is not very common in the maker community.
I also wanted to machine the base and load cell supports myself, which was exciting as I don't get to use the mills and lathes of my university very often as I'm an EE student.

Please consider buying the original product if you can afford it, it's a great product and it's worth the price (thanks F4IEY for showing it to me in the first place !).

Pictures​

3D Render from Autodesk Fusion​

Force render

Base machining​

machine shop

The final base ended up being 90x85x20mm due to the available scrap blank; the CAD was then adapted to fit the new dimensions.

It was amazing to be able to use the machines of my university. It took a whole afternoon to machine both parts (base and load-cell support), but it was really fun ! Thanks again to my teacher for all the help and advice.

Base bluing​

Before :
before bluing

After :
after bluing

After a lot of sanding with 180 and 320 scotch-brite, I used a cold bluing solution to give the base a nice black finish. It's not perfect nor uniform, but it gives a great old-school look to the base.

Assembly​

Partial assembly before bluing :
assembly

Assembly before bluing :
assembly

Partial assembly after bluing : assembly

Final assembly :

assembly

License & Acknowledgements​

Made with ❤️, lots of ☕️, and lack of 🛌
Published under CreativeCommons BY-SA 4.0

Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.