Hello all,
I am having problems using a differential Op Amp to detect voltage drop across a small shunt resistor:Voltage drop across it is about 0.04v
I set up the Op amp as an ADC input with op amp gain of 2 (i think):
10k on both Vin pins to op amp with the ground resistor and the feedback resistor as 20k.
When current flowed through the shunt, the ADC value increased by 2 (and it was stable: only occasionally fluctuating +-1 from the increased value )
However, I would prefer a throw of perhaps 4+ debug values but when i set up for 4x gain (replacing the 20k with 40k), the ADC values went haywire!
It was fluctuating +-10 values and i have no clue what is going on.
Also, when current through shunt was 0, i got an ADC value of about 140...Why is this and can i reduce it whilst getting higher gain?
Because i would prefer to start much closer to 0 and get more playing room
Help would be very much appreciated,
Thanks in advance,
D
I am having problems using a differential Op Amp to detect voltage drop across a small shunt resistor:Voltage drop across it is about 0.04v
I set up the Op amp as an ADC input with op amp gain of 2 (i think):
10k on both Vin pins to op amp with the ground resistor and the feedback resistor as 20k.
When current flowed through the shunt, the ADC value increased by 2 (and it was stable: only occasionally fluctuating +-1 from the increased value )
However, I would prefer a throw of perhaps 4+ debug values but when i set up for 4x gain (replacing the 20k with 40k), the ADC values went haywire!
It was fluctuating +-10 values and i have no clue what is going on.
Also, when current through shunt was 0, i got an ADC value of about 140...Why is this and can i reduce it whilst getting higher gain?
Because i would prefer to start much closer to 0 and get more playing room
Help would be very much appreciated,
Thanks in advance,
D