Ake Hedman wrote: > I need some advice comments on this circuit > http://www.vscp.org/images/barometer001.gif You probably laugh your > guts out but but when you finished laughing please tell me what I have > done wrong. You have the inputs to the opamp swapped. Another way of saying this is that R4 needs to be the one connected to the opamp output and R3 needs to be grounded. And also R2 needs to be 10K, not 100K. -- Dave Tweed -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist