I have an air flow sensor (FS1012-1100NG) with expected differential output voltages ranging from -1mV to 20mV and I need to 1) know the precise value (mV) and gain to correlate V with airflow 2) make sure that value has long-term stability (order of days) and 3) end up with a voltage that makes the best use of my 12bit ADC.
I'm using an AD623 with a single supply (3.3V) with the FS1012 connected per the datasheet (see image).
- pins 1&8 Gain Resistor (I've tried 100ohm-1Mohm but no change in output/gain)
- pins 2&3 TP2+ and TP1+ (I've checked these and there is a differential voltage of about 2-3mV at max airflow)
- pins 4&7 Ground and 3.3V
- pin 5 Ref (Tested 0-3V using voltage divider, no change in output/offset)
- pin 6 Output (to digital multi-meter with ref to ground)
What am I doing wrong? Is there a better differential amplifier I should be using? Thank you in advance!