A shockingly basic question

[Tim Cockram]

Hi

The resistor to ground from the non-inverting input of the op-amp is there to supply the bias current 
to the op-amp.  OK so most basic analyses ignore the bias current but it is real (if potentialy quite small) and 
necesary.

Re the ground loops the only shure way is to use a transformer which has no reference to ground at all.  However 
the basic differential amp can provide an improvement in the right circumstances.

There was a very good article on grounding etc in the AES journal in the recent past.  I will try to dig it put and post the 
reference.

Regards etc.

Tim


-------------------------------------
Tim Cockram
E-mail: tim at redragon.demon.co.uk 

Phone:-UK-1222-384041
Fax:-    UK-1222-390326


-------------------------------------