Charles: We are losing sight of this thread's purpose - to assist in solving a substitution induced problem. The manufacturer of a part specs that part in the most favorable light for that part, never concidering the concequences of inserting the part into a useful circuit that may actually contain parts from other manufacturers, and even substitutions ( of any part) after the design is complete. These unplanned changed are what separate engineered solutions from hobby designs. This forum repeatedly has examples of this. The guidelines and layout rules suggested are all well documented in many professional trade magazines available to all that qualify further I have even actually heard that some engineereing courses teach these guidelines. Suggesting that they are not valid because you have not seen them in a manufacturers data sheet is unhelpful and even counterproductive . Eric/Rob keep up the good work Thanks Terry Lingle