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[SOLVED] CDM7160 - PPM Value Oscillation
#5
Lightbulb 
Here are some more details, how the output of the CDM7160 changes once a simple EMI filter is applied by insulating the sensor with electrical tape, wrapping it with some aluminium foil and connecting it via some alligator clip to ground. It is a pity the manufacturer (FIGARO) of this sensor released such an immature product... but - that's life. Luckily it is fixable.

The problem with aluminium foil is that you cannot solder it easy and connect it to ground. I have also somewhere some roll of copper foil, but i couldn't find it yet. In the next couple of days i will check what is the best way to patch it, w/o having to send them back to me. It will be something like a patch of adhesive copper foil with a soldered connector that you can easily wrap around the sensor. Of course there will be the possibility to send me back the device for repair (free for you of course) if you do not want to fiddle with this

And here are the results (Note - those are the raw results, taken each 30 seconds.)
This one was oscillating pretty hard when i put it on a special place on my desk. @~17.20 i applied the fix, then few minutes later tried temporarily disconnecting ground to see if it necessary - it was. Below is another one

[Image: cmd7160_EMIshield.png]

This one was oscillating +/- 50 ppm. Initially this is what i had discovered about this sensor. While not ideal i decided that if this is the raw output, other sensors anyway apply some smoothing, so maybe this is it. In fact after applying smoothing those fluctuations got more or less hidden.
Yet -after applying the fix to this sensor as well - the raw output's fluctuations went down to +/-5 ppm. Given the fact that the resolution of the CM1102 is 10 ppm, i believe this is in the range of acceptable error for those sensors.

[Image: CDM7160_EMIFilter2.png]
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Messages In This Thread
RE: CDM7160 - PPM Value Oscillation - by admin - 10-12-2016, 08:55 AM
RE: CDM7160 - PPM Value Oscillation - by admin - 10-14-2016, 08:06 PM
RE: CDM7160 - PPM Value Oscillation - by admin - 10-15-2016, 04:01 AM

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