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Q-Prox Touch Switches - SparkFun Electronics

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By JonChandler
Has anybody tried the Q-Prox touch switches? They have chips designed to make a keypad as well as sliders and rotary spinners.

These look pretty cool....place a circuit board pattern behind the plastic panel of an enclosure, and you can have a keypad or slider any shape you want. I have one of their 4-button demo boards and it works great I put an eighth-inch thick piece of plastic over the circuit board patterns with a piece of double-backed tape and it reliably detected every "press" of the four buttons.

I'm curious how picky the circuit is with the capacitance values in the sense lines, or other fiddly bits are required in the circuit board arrangement.

These parts look like a good solution where a keypad is desired in a sealed enclosure - just stick the PCB to the inside surface.


Thanks for any comments,

By jayjay
I bought the QT110 kit and the keypad kit. The single electrode chip seems to quite stable, however their keypad matrix one did not do so well, in fact their demo kit out of the box failed miserably. I could be doing something wrong, but never got to do anything useful with it. I dumped it and used the Motorola's E-Field chip for a touch switch application.

By Ralph_Hilton
I just got some QT160 6 channel chips. They work very reliably. With 10nF caps it senses fine through 3mm plastic using 1 x 0.5cm tin sheet for sensors. With 22nF using 0.5 x 0.5 tin it senses a few mm above the plastic. 47nF makes it sensitive to a hand moving nearby..