Touch sensor TTP223 for fischertechnik

Enclosure for TTP223 mini touch sensor modules with a 5mm fischertechnik building block form factor.

For assembly, simply solder a male or female 3 pin header in a horizontal position to the module and slide it into the enclosure's slot opening.

See also [this design](https://www.thingiverse.com/thing:5370866) using conductive filament.

Updates:
2022-04-28: Added BS15 version. Try this without capacitor, first, as the board is aligned for a perpendicular touch in this design.

### Adjusting sensitivity

My sensors were very sensitive and triggered a couple of mm before actually touching the enclosure, which made them proximity sensors, not touch sensors. The module has an unlabeled soldering bridge above the IC where you can add a SMD capacitor of 0-50pF to adjust the sensitivity (cf. [datasheet](https://datasheet.lcsc.com/szlcsc/TTP223-BA6_C80757.pdf)). 22pF worked well to turn it into an actual touch sensor.

### External contact vs. built-in contact

If you want