Help resolving Instrumentation Amp.

Not open for further replies.

Thread Starter


Joined Jun 17, 2004
Hello Gents
I am having a problem trying to resolve a circuit with an instrumentation amplifier in which the voltage applied to the top buffer circuit is –3v and +2v to the bottom one.
Is -5v the difference of potential? and 0.5mA the current? is the current flowing towards the top buffer?, if I am right on this, what is the difference of potential between the two outputs of the buffers?
Thanks in advance.


Joined Nov 17, 2003
Assuming you are using a standard Instrumentation Amplifier, your source voltage will be the difference between the two rails, i.e. v1 - v2, which I assume is the 5V you talk of.

As for current, you will most probably be expected to assume ideal conditions, therefore the current is given by the source voltage divided by the resistance present between the inverting inputs to the two input op amps, Ri:

I = v1 - v2 / Ri

A diagram of your problem would probably make solving the problem easier.

Thread Starter


Joined Jun 17, 2004
Hello Dave,
Sorry for not making this clear enough, but it is the first time that I post a message to a forum....
The day after I post this this problem and I decided to use electronics workbench to find out if the calculations I did we right, and now it is solved.
Thanks anyway for your help.

i have implemeneted tweo op-amp based inst amplifier. one NI IS KEPT AT 100 MILI VOLT wrt to other.

i ma not gettin g 10.23 volt out put.

both op-amps are supplied at 12 volt dc. pin 11 is at grd.


Joined Apr 5, 2008
Welcome to AAC.

Congratulations, you have practiced the arcane art of necromancy, the revival of a long dead thread. Likely the OP (Original Poster) has solved his problem in the years that has passed, or thrown it away, or something.

Please STOP digging up old threads.

Please start your own thread.
Not open for further replies.