Pheetuz
Full Member level 3
I posted earlier about an A/D converter project i was working on, which was all going very smoothly untill I realised I had made a mistake.
The project I am doing involves measuring a 15mV change on a 24V signal, which i was doing by using a potential divider to step down the voltage to about 2.4V and then searching for the 15mV change on that signal.
I forgot to take into account that the 15mV change I was looking for would have been attenuated by a factor of 10 and would now be 1.5mV, way below the accuracy of my A/D converter. - Really stupid of me I know...
Basically, I need a way to take 22V off of my signal whilst leaving the other 2.4V as they are, this would be ideal as my code would not need changing!!!
Or:
I have two signal that I am comparing the difference between, one should be exactly 24V and the other should be between 24.015V and 24.2V, it is this difference that I need to measure, I was thinking that i could use an OPAMP to remove the common signal and just leave me with a value between 0.015V and 0.2V, well within the range of my A/D converter.
The only problem is that I have no experience using OPAMPs and am not sure if this is realistic? How accurate would the signal be copied from one side of the OPAMP to the other ???
Also, if anyone has any circuit diagrams of a potential circuit, it would be much appreciated!
Many thanks.
Pete
The project I am doing involves measuring a 15mV change on a 24V signal, which i was doing by using a potential divider to step down the voltage to about 2.4V and then searching for the 15mV change on that signal.
I forgot to take into account that the 15mV change I was looking for would have been attenuated by a factor of 10 and would now be 1.5mV, way below the accuracy of my A/D converter. - Really stupid of me I know...
Basically, I need a way to take 22V off of my signal whilst leaving the other 2.4V as they are, this would be ideal as my code would not need changing!!!
Or:
I have two signal that I am comparing the difference between, one should be exactly 24V and the other should be between 24.015V and 24.2V, it is this difference that I need to measure, I was thinking that i could use an OPAMP to remove the common signal and just leave me with a value between 0.015V and 0.2V, well within the range of my A/D converter.
The only problem is that I have no experience using OPAMPs and am not sure if this is realistic? How accurate would the signal be copied from one side of the OPAMP to the other ???
Also, if anyone has any circuit diagrams of a potential circuit, it would be much appreciated!
Many thanks.
Pete