Capacitive Proximity Sensor

aaronik19 · Joined: 25 Apr 2011 Posts: 296

Dear All,

I am making a design and I am looking for a Capacitive Proximity Sensor with external sensitivity trimming (not the one on the sensor) since the sensor will be mounted 20 meters high on a conveying pipe.

Do you ever used such sensor? I am also interesting to build this sensor as well in case it is not available, but the problem is where I can buy the plates of the capacitance sensor? Can I use Touch Sensor breakout board to sense powder product in a conveying pipe?

Thanks for your help

newguy · Joined: 24 Jun 2004 Posts: 1903

I'd be inclined to say that in order to get repeatable results, you're going to need some precision with your prototype sensing plates. In my mind, that means a custom PCB just for the sensing elements. You can prototype using almost anything as your capacitive sensing plate(s), but when you try to move the design to something final/"nice", you're going to have issues.

temtronic · Posted: Thu Dec 22, 2016 12:52 pm

this...
the sensor will be mounted 20 meters high on a conveying pipe.

probably is not going to work well...

20meters=60feet+-, 'noisy' industrial environment...dirt,EMI,humidity, etc...all factors in cap sensor tek.

Would need to know more about the 'environment' but I'm inclined to use a slave PIC, run RS485 and power from the 'master' PIC. Better yet some form of cabling/comm tech that KNOWS when the cables cut.....

Jay

Mike Walne · Joined: 19 Feb 2004 Posts: 1785 Location: Boston Spa UK

aaronik19 · Joined: 25 Apr 2011 Posts: 296

At the moment we are using the IFM capacitive sensors http://www.ifm.com/products/gb/ds/KI5083.htm and is working perfectly but the problem is that once it is connected, it is very hard to adjust sensitivity in case it loses the tuning due to product change. The power is being conveyed using an air blower pressure of 500mBar and flow rate of 5000m3/h.

I am looking for something that in case sensitivity need to be tuned, it can be done from a control panel.

Ttelmah · Joined: 11 Mar 2010 Posts: 19255

Not with that sensor.

There are several manufacturers who do smart sensors where you can program the trigger point, or you use a simple analog output sensor, and program the reference voltage remotely. Or just design your own based on one of the 8pin PIC's with capacitive sensing built in, and have a serial connection to program the level.

Do a search for Efector150 and Efector160. These include models, where the zero point can be programmed remotely by a pulse on the programming wire. They also have a slightly better detector design, making them more immune to drift.

Talk to Ifm (the manufacturer of the above). If I remember correctly, they were even offering Internet programmable versions.

You make the plates in the PCB inside the casing. Design affects the sensing region shape. Also using multi-layer boards allows you to reduce the effects in different directions. Lots of work learning about capacitance.....

What is strange is that you are using the 'dumb' version from the same manufacturer. One 'rule' is 'talk directly to the technical people' for this sort of question. Generally manufacturers want you to use their products, and will be quick to tell you that they do a smarter version that can help!...

For a 'smart' sensor, look at the Gill GS4223. Has two outputs and serial. You can program an output to be a level switch, and configure what fluid you are sensing, and the level you want to switch at.