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QT 113

The QT113 is a capacitive touch sensor that operates like a switch.

Here are the parts you will need:

The QT113 is a touch sensor. From the pin labeled OUT, the QT113 sends a digital HIGH when a touch is detected and a digital LOW when there is none. The OUT pin is connected to an input pin on a microprocessor.

The SENS pin is the input. For testing, a simple wire can be used on this pin. Later when the application is fully realized, Other materials can be used. Copper mesh, metal plates, and conductive fabric are examples. Just about aby conductive material connected to the SENS pin will become part of the sensor.

there are two OPT pins OPT1 and OPT2. These option pins, when set to a combination of power and ground, determine the behavior of the output signal.

The following chart described the behavior of the sensor. The MAX on duration refers to the amount of time the sensor stays active once touched

  • OPT1 OPT2 MAX on duration
  • pwr pwr 10 sec
  • pwr Gnd 60 sec
  • Gnd Gnd Toggle
  • Gnd pwr infinite

The GAIN pin sets the sensitivity with a digital HIGH or LOW depending on preference.

In examining the board, notice the pads labeled CX. This is for a .1uf ceramic disk capacitor. The capacitor can be switched with other values depending on your situation. The more capacitance, the more sensitive it will be. We are using female headers here. They are acting as a socket so that we can swap out capacitors.

Pin description:

  • +5 this is the logic supply for the chip, connected to a 5 volt power supply
  • GND this is connected to ground
  • OUT this is connected to a digital input on your micro controler
  • SENS this is the sensor pin. Connect one end of a a wire to this pin for testing
  • OPT1 this is an option pin - see above chart
  • OPT2 this is an option pin - see above chart
  • GAIN this is the gain, it has 2 settings, HIGH and LOW.
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