To everybody that helped (Larry, Lucas, Bob, Sphero, Russell, Phil ... etc), Thanks so much. I am now getting what I am expecting at the output of the op-amp but more importantly it finally "sunk in" on figuring out the gain, voltage and offset! Thanks again guys, as always the list comes through. Steve Larry Bradley wrote: Bingo! Forgot about that! I was treating it like a summing amp, (i.e. same as applying minus 1.218 via Ri to the inverting input and connecting V+ to ground). At 06:21 PM 2/11/2004 -0300, you wrote: > > Now, given an gain of 16.166666, to add 19.7 volts to the output requires > > > adding 19.7/16.17 = 1.218 volts to the reference input. > > > >Assuming Rf between Opamp's output and inverting input. > >Assuming Ri between Opamp's inverting input and signal input. > >V+ applied at the Opamp's non-inverting input > > > >Don't forget that the gain for the non-inverting input is 1+Rf/Ri (assuming >Rf as the feedback and Ri as the input), so: > >V+ = 19.7 / (1+16.667) = 1.1475V > > > >I simulated this before post, seemed to work. > > > >Lucas Hartmann > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > Larry Bradley Orleans (Ottawa), Ontario, CANADA -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads --------------------------------- Do you Yahoo!? Yahoo! Finance: Get your refund fast by filing online -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics