Thanks to all who replied on the op-amp problem. Yeah, it was a case of RTFM (or should I say, RTFDatasheet ). I was exceeding the common-mode input range,as was suggested by some of those who replied. Sean | | Sean Breheny | Amateur Radio Callsign: KA3YXM | Electrical Engineering Student \--------------=---------------- Save lives, please look at http://www.all.org Personal page: http://www.people.cornell.edu/pages/shb7 mailto:shb7@cornell.edu ICQ #: 3329174