You havn't thought of trying this using an external "true" rail-to-rail opamp as comparator ? Perhaps not what you would like to use, but it would be nice to see it you'd get a full 0-5 V range that way. Jan-Erik S=F6derholm -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body