fleamonkey
New Member
hi , new to this site so hi to everyone!
i have a wheatstone bridge connected to an op amp
I have designed this circuit to measure resistance of paper. R1 is noted as a varible resistor - this is acting as my probes. It is 14k ohms as that is the base line for my paper and also to balance the bridge.
The problem i have is that every time i vary R4 the gain of the amp changes?!
Im sure i am doing something stupid somewhere.
can anyone point me in the right direction please?
thankyou
i have a wheatstone bridge connected to an op amp
I have designed this circuit to measure resistance of paper. R1 is noted as a varible resistor - this is acting as my probes. It is 14k ohms as that is the base line for my paper and also to balance the bridge.
The problem i have is that every time i vary R4 the gain of the amp changes?!
Im sure i am doing something stupid somewhere.
can anyone point me in the right direction please?
thankyou