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Hi. i need a pcb type capacitive sensor, which will detect any object on it. I am planning to put it on a pcb, then i will put a 10mm glass on the sensor. It must have adjustable sensitivity. Do you know such a sensor. ]
You can try using a Filter type circuit. When you come close to the circuit, the capacitance of the circuit changes, and thereby the amplitude of an AC signal passing through the circuit changes. You can rectify this signal and use a voltage comparator to determine if it is toggled or not.
In the second link, scan down to Fig. 3.1.3. NASA/Goddard did a lot of work on capacitance detectors for object avoidance, like when exploring the inside of a rocket engine. That work was published in the public domain, so it can be duplicated. Unfortunately, all of the links I had have gone bad and direct to pages that charge to download. I have attached a report that is only 23 KB. The appendix to the report has lots of good information, but is 3.2 MB, so I didn't upload it. You may want to just search on "capaciflector," which is simply a capacitance detector with an additional electrode that reflects/focuses the detection field. I built a couple of versions , and they do work. Here is a cross-section of one detector and the circuit I built:
Hi. i need a pcb type capacitive sensor, which will detect any object on it. I am planning to put it on a pcb, then i will put a 10mm glass on the sensor. It must have adjustable sensitivity. Do you know such a sensor.