Capacitive touch switch

270

04:18:37

Capacitive touch switches work by sensing the capacitance you add to a circuit when touched. If the circuit is an RC oscillator you can see that its frequency changes quite a lot and so the circuit can sense when a metal part is touched or not.
While building my last hexapod robot i thought it would be nice to make it sensible to human interactions, so i designed this. I think i will make a small RC oscillator and monitor its frequency with the onboard stm32f103vet6.
-nik

published 7 years ago

lenzrulz

7 years ago

Have you factored ESD into your circuits equation because a human and surroundings constitute a highly charged capacitor. Synthetic fabrics and friction can charge a human body to about 3 kV or more. Notably, a combination of footwear with some sole materials, low humidity, and a dry carpet (synthetic fiber in particular) can cause footsteps to charge a person's body capacitance to as much as a few tens of kilovolts with respect to the earth. BTW, the Human Body Model for capacitance is a 100pF capacitor in series with a 1.5kΩ resistor.

Issacsutt

7 years ago

How do you know what the human body model of a cap with its appropriate values are?

carlos2201

7 years ago

Pure shit

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