AT42QT1010:

  * [[https://learn.adafruit.com/system/assets/assets/000/009/807/original/proximity_AT42QT1010.png?1396897662|AT42QT1010 schematic (Adafruit)]] (Filimin using C1=10nF, 5nF worth trying, higher=more sensitive)
  * [[http://www.atmel.com/images/atmel-9541-at42-qtouch-bsw-at42qt1010_datasheet.pdf|data sheet]]
  * [[http://www.atmel.com/Images/QTAN0062.pdf|Sensitivity Tuning]]
  * [[http://atmel.force.com/support/articles/en_US/FAQ/Improving-noise-immunity-with-AT42QT1010-device|Improving Noise Immunity]]

TTP223:

  * [[http://www.tontek.com.tw/download.asp?sn=475|data sheet]]
  * [[https://www.openimpulse.com/blog/wp-content/uploads/wpsc/downloadables/TTP223-Capacitive-Touch-Sensor-Module-Schematic-Diagram.pdf|schematic for generic module]]

These 2 ICs are not pin-compatible. For both a higher Cs reduces sensitivity.