Hi everyone,

I'm new to this field. When I wished to make a bridge circuit output linear I found a circuit, I have attached circuit in the attachments. In circuit description it is mentioned that irrespective of the resistance change in the branch, current would still remain same (Ib/2). Here my doubt is how come even resistance is changing branch current is same in the both the branches. Please clarify my doubt someone in the forum. Thanks in advance.

 

ΔR appears in both branches so as ΔR changes both branches change by the same resistance so the current in the two branches is equal. The total current is kept constant by the opamp as described and so the current in each branch remains constant as ΔR changes.

 

ΔR appears in both branches so as ΔR changes both branches change by the same resistance so the current in the two branches is equal. The total current is kept constant by the opamp as described and so the current in each branch remains constant as ΔR changes.

Quite a common (if clever) little circuit there.

 

The current in each branch of the Wheatstone bridge will remain the same as the initial conditions only if the resistances change equally. The sum of the currents in the two branches will remain constant, regardless of the changes in the resistance (within the limitations of available voltage and current).

I'm not sure I answered your question. Reply if I missed your point.