Hey everyone,
I have a voltage source from a sensor that goes from -15 to +15V and I want to scale and offset it so I can read it somewhere between 0-3V. The scaling doesn't need to be exact and there can be some offset, since the measurements for this don't need to be accurate at all (8 bits).
I'm using an op-amp to buffer the sensor output since it's sensitive to loading, and then I just scale and offset it using an op-amp as shown in the attached image.
It "simulates" fine in Falstad, but in the real world I'm having some difficulty..
At sensor output +15V, the circuit outputs .5V [good!]
At sensor output 0V, the sensor outputs about 1.4V [good!]
At sensor output around -13.77V the output is about 2.4V [good!]
But at sensor output lower than -13.77V down to -15V the output switches direction and goes back to .5V as it approaches -15V.
Is there a problem with offsetting and scaling a rail to rail voltage with a single op-amp stage like I'm doing and is there another way of doing it?
I have a voltage source from a sensor that goes from -15 to +15V and I want to scale and offset it so I can read it somewhere between 0-3V. The scaling doesn't need to be exact and there can be some offset, since the measurements for this don't need to be accurate at all (8 bits).
I'm using an op-amp to buffer the sensor output since it's sensitive to loading, and then I just scale and offset it using an op-amp as shown in the attached image.
It "simulates" fine in Falstad, but in the real world I'm having some difficulty..
At sensor output +15V, the circuit outputs .5V [good!]
At sensor output 0V, the sensor outputs about 1.4V [good!]
At sensor output around -13.77V the output is about 2.4V [good!]
But at sensor output lower than -13.77V down to -15V the output switches direction and goes back to .5V as it approaches -15V.
Is there a problem with offsetting and scaling a rail to rail voltage with a single op-amp stage like I'm doing and is there another way of doing it?