Dear all, i have a project where i need to use capacitive proximity sensor to sense a non metallic product. Do you know with a kind of sensor where i can adjust the sensitivity from 3-5meters away from the sensor?
Capactivie proximity sensors require the thing you're sensing to be conductive. If your non-metallic object is non-conductive, you cannot detect it with a capacitive proximity sensor.
3-5m is also really really long for a cap proximity sensor - like, an MTCH101 with a large sensor area and sensitivity near max can detect a person at a meter or two away, but at that point, its very sensitive and gets a lot of false positives and stuff.
I think you need to reevaluate you choice of type of sensor.
aaronik19:
Dear all, i have a project where i need to use capacitive proximity sensor to sense a non metallic product. Do you know with a kind of sensor where i can adjust the sensitivity from 3-5meters away from the sensor?
Sounds like you need one of these:
You can adjust the sensitivity and directionality by shielding. (You add a resistor to adjust overall sensitivity.)
Alternatively consider an ultrasonic sensor.
Thanks for your reply. Seems that I might did not explain myself well. My client has a pipe full of food powder and I need the sensor to sense if it full or empty. That's why I choose capacitive sensor since the medium is non-metallic. Now my next issue is, that the sensor will be mounted about 3 to 5 meters up, and it is not accessible to adjust the sensitivity during the production. That why I need to Sensitivity trimmer to be in the panel near the machine controller.
A capacitive sensor cannot sense a non-conductive material (which the food powder probably is) and cannot do it at that kind of range regardless.
You need different sensor technology. Ultrasonic ranging sensors are apparently used for this (you can even get nice ones in more durable housings that can keep the crap out of it for this sort of thing). That microwave ranging board might also work. Challenge will be not getting false signal from the pipe.
Are you sure conductivity is the important property for capacitive sensing? I would say permittivity, which is not exactly the same. Or not?
Smajdalf:
Are you sure conductivity is the important property for capacitive sensing? I would say permittivity, which is not exactly the same. Or not?
Correct. For a pipe full of material, capacitive sensing would be just fine, but you need (insulated) electrodes running down the length of the pipe. Not at one or other end. It is not proximity, it is quantity.
The radar device senses only movement, not absolute distance or capacity, so not suitable for this task. Ultrasonics are (much) less effective detecting soft, absorbent material though will sense a liquid level (air/ liquid interface) very well if perpendicular to that interface.
aaronik19:
Seems that I might did not explain myself well.
Ah! You fell foul of the first rule of the forum. And the XY problem.
Unless you explain what the situation really is, you waste a lot of people's time. 
1/ Can you weigh the pipe? with eg a load cell.....
2/ If the pipe is transparent an optical sensor might work.
Allan
DrAzzy:
A capacitive sensor cannot sense a non-conductive material (which the food powder probably is) and cannot do it at that kind of range regardless.
You don't understand the kind of capacitive sensor involved. The OP confused us by using the word "proximity" which is not what is meant here at all.
Capacitance is dependent on the dielectric, and food powder will have a very different dielectric constant from air.
Presuming the pipe is non-metallic - some sort of plastic?
Over it's length symmetrically fix two equal areas of eg copper foil outside covering perhaps 2/3 the surface area.
Depending on the size , plastic, and geometry of the pipe and the dielectric constant of the food powder you should see a significant change in capacitance between these two electrodes depending on how full the pipe is.
The only way is to try it - there are too many variables to guess.
Allan
Draw a picture.
Wiil do tomorrow. Isn't the idea obvious?
Allan
allanhurst:
Wiil do tomorrow. Isn't the idea obvious?
I think it's quite obvious, and you of course think it's obvious as you know the ins and outs of the system. That doesn't make our obviousnesses (according to my spell check that's actually an existing word!) necessarily the same. That's why a picture of the actual device (preferably with other details such as dimensions, materials involved, etc) is needed, so we're all thinking and talking about the same thing. Otherwise... well... another version of the XY problem.
Paul__B:
Correct. For a pipe full of material, capacitive sensing would be just fine, but you need (insulated) electrodes running down the length of the pipe. Not at one or other end. It is not proximity, it is quantity.
Agreed. This is akin to how I use capacitance to measure fluid level of nonconducting liquids. I'm relying on the capacitance increase caused by the permittivity of the liquid acting as a dielectric. The pipe should be insulating, and of course the electrodes must be fully insulated, too. The permittivity of the food powder needs to be substantially more than 1 to get a reasonably good reading.
You can put an Arduino right there and have a box with some kind of adjustment mounted at a distance. Could be just a potentiometer, or a couple of buttons for up/down control. You will need to zero out the capacitance when empty, then fill it and calibrate to full. I suspect it will respond more to the total mass of the powder, rather than height, so 5kg packed tight or not packed in may give about the same reading. Which would be a plus.
Unless you explain what the situation really is, you waste a lot of people's time.
Great advice.
allanhurst:
Wiil do tomorrow. Isn't the idea obvious?
My apologies, I was asking aaronik19 to draw a picture of how this is currently set up.