Help with a circuit.....

[johnkaz77]

Hello,i have this circuit which sources or sinks current and i should control Vin- and Vin+ with a pot with its 2 edges connected to a negative and a possitive power supply respectivelly.First of all i would like someone to explain how this circuit works because i don't really understand and second,can i supply the voltages Vin only from one potentiometer as i was told?If the two inputs of the op amp are the same how can it work?Is there something else i have to do and i don't get it?

 

[sv1437]

Did you try to simulate the circuit in any circuit simulator (like Pspice). First, I would try to simulate, give some arbitrary voltages at Vin+ and Vin- and measure the output and see how the output is affected by the change in input voltage.

 

[aminoacid]

it appears that the circuit "in my opinion" act as an instrumentation differential amplifier, with the lower OP-AMP mounted as a buffer in the feedback loop to monitor the load.

for the POTS, if the idea is to simulate a differential input as to measure the CMRR then it would be ideal if this is a dual one where the +VCC and -VEE are connected so that when you increase the voltage on the (+) side it will increase in the (-) by the same amount.. I guess..

Best regards.