Sensor project
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I working on a small project which requires me to read a sensor which
outputs from 0 mv to 400mv +/- 40 mv full scale. It's almost linear but
does have a couple of items that could use some error correction. I have
several questions regarding the electronics end and some on the math end.
The sensor is an Oxygen sensor that reads from 0% to 25.5% o2. At 21% o2 it
reads approx. 400mv.
I don't know much about OP Amps but willing to learn. I figured I would use
an 8 bit ADC with a 4.096 reference, then use an OP Amp with a Gain of 10.
I thought about using a pot to slightly adjust the gain in order to
calibrate the sensor. The sensor always has zero output when it senses zero
input, so I was only going to adjust the high end. Would this be the proper
procedure?
Next, the sensor exhibits a Temp Coefficient of 0.2% signal / Degree C so I
may want to perform a temp. correction for the temp at the sensor. The temp
would range from about Ambient (32F to 100F) to about 150 Degree F when
operating in it's environment. It's calibrated in an Ambient condition. I
was leaning towards using an Thermistor to measure the temp during
calibration, then correcting the displayed units for the operating temps.
Any input would be greatly appreciated.
Richard
outputs from 0 mv to 400mv +/- 40 mv full scale. It's almost linear but
does have a couple of items that could use some error correction. I have
several questions regarding the electronics end and some on the math end.
The sensor is an Oxygen sensor that reads from 0% to 25.5% o2. At 21% o2 it
reads approx. 400mv.
I don't know much about OP Amps but willing to learn. I figured I would use
an 8 bit ADC with a 4.096 reference, then use an OP Amp with a Gain of 10.
I thought about using a pot to slightly adjust the gain in order to
calibrate the sensor. The sensor always has zero output when it senses zero
input, so I was only going to adjust the high end. Would this be the proper
procedure?
Next, the sensor exhibits a Temp Coefficient of 0.2% signal / Degree C so I
may want to perform a temp. correction for the temp at the sensor. The temp
would range from about Ambient (32F to 100F) to about 150 Degree F when
operating in it's environment. It's calibrated in an Ambient condition. I
was leaning towards using an Thermistor to measure the temp during
calibration, then correcting the displayed units for the operating temps.
Any input would be greatly appreciated.
Richard