Touch sensor TTP223 for fischertechnik

thingiverse

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 to use this module with your own touch contact instead of the touch plate at the back of the PCB, use a 4 pin header and connect the additional pin to the IC's pin 3. Scratch the solder mask from the trace leading to it for easier soldering (see images). Connect any conductive contact to that pin (e.g. some fischertechnik metal part) or leave it unconnected to use the built-in contact. ### Built-in LED The built-in LED is very bright and easily shines through my red enclosures. If you use a darker filament, you can try the _LED variant of the .stl file. It has a hole for a short piece of 1,75mm transparent filament acting as a light guide. ### Module configuration options There are two more soldering bridges labeled A and B. You can use them to change the active output from high to low (A) and to put the module in toggle instead of direct mode (B). See [datasheet](https://datasheet.lcsc.com/szlcsc/TTP223-BA6_C80757.pdf) for details. https://www.youtube.com/watch?v=iABhU9tCzkg