Hi. I am currently trying to use a capacitance sensor to measure percentage of air in a air-water mixture. The sensor itself is just two aluminum foils attached outside a pvc pipe. The outer side of the aluminum foils are shielded so that only electrical field disturbances in the pipe is measured.
I have seen and tried many circuits, all of them quite complicated for me (I am a mechanical engineering graduate with very limited circuit knowledge) and I am wondering why a simple circuit (Figure 1) would not be used?
Value of R1 is set based on the range of capacitance that needs to be measured from C1. So, fluctuating value from capacitance sensor C1 will induce different voltage drop for R1, and the diode and C2 straightens the signal so that the final measured voltage is a rectified signal.
So my question is, is there any downside of using this circuit? I know it works because I used it, but I can't help to wonder if people with good electronics and circuit background know why this simple circuit is not used by others.
Figure 1
I have seen and tried many circuits, all of them quite complicated for me (I am a mechanical engineering graduate with very limited circuit knowledge) and I am wondering why a simple circuit (Figure 1) would not be used?
Value of R1 is set based on the range of capacitance that needs to be measured from C1. So, fluctuating value from capacitance sensor C1 will induce different voltage drop for R1, and the diode and C2 straightens the signal so that the final measured voltage is a rectified signal.
So my question is, is there any downside of using this circuit? I know it works because I used it, but I can't help to wonder if people with good electronics and circuit background know why this simple circuit is not used by others.
Figure 1