my goal is to use Arduino with 2 proximity probe sensor to achieve some output like orbit plot for a shaft mounted on a bearing
the system
the orbit plot
the proximity probe sensor has a negative voltage output from 0 to -24 volt, as the arduino accepts voltage only in the range of 0 to 5 volt,so I decided to use op-amp to invert and to scale down the voltage so instead of being in the range 0 to -24 v, it will be 0 to 5 v
worth mentioning that, the output of the proximity probe has 2 components:
1- DC out put that determines the position or the GAP
2- AC component on the top of that DC voltage to determine the vibration
my questions are :
1- how can I get to separate the ac from the dc component ? I mean like I want to use the DC value to determine the GAP and the AC to determine the vibration, should I use AC coupling ?
2- is this configuration and the whole idea applicable and reliable ? I mean using arduino and then using the op-amp invert and to scale down the voltage ? is there a better and cheaper way to do this?
please correct if I am mistaken at any point, sorry this is my first experience with this proximity probe thing, and some questions may seem silly and this is what I managed to get after a lot of searching
Best Answer
Capacitive coupling to an opamp circuit will allow the AC through but block the DC but your AC signal will be centred around zero so you may need to use a level shifter to centre at +2.5 volts, in the middle of the ADC input range.
For the DC, take the output from the sensor and use a low pass filter (R and C and or L) to remove the AC component.