V G wrote: > 2. Is it critical what opamp I use for the right leg driver? Can I > use an LM324? That should be fine. Strictly speaking, you don't need a right leg driver at all. However, especially when your diff amp common mode rejection is suspect, its a good idea. It's a low frequency signal that mostly just has to drive the body capacitance, so just about anything, including a LM324 should be fine, assuming it can drive with enough range. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .