thank you for your reply, it isn't a state secret, I just didn't want to write a book, I am working on interfacing a motorized wheelchair with arduino, the' analog read' reads 0-5 volt, using a single side supply op amp I get about 3 volt useable signal to the 'analog read'( because weight of hand on control sensor)im thinking if I use a negative /positive opamp I can bias from the negative to 0volt (to compensate for weight of hand) and then have the 0-5 volt range to use in processing. will 5.1 zener in series work without loading down current draw