I'm not sure how sensitive, but I would guess if there is a strong nearby field, it would affect it. Next time the Allegro FAE comes around, I'll ask him that. I "Alan B. Pearce" wrote: >So, for now....I'm leaving in the Allegro hall sensor and >op-amp and just see if I can function with that or just.... >leave that piece out. Its not the most critical part of the design. Another option would be to use a second stage of gain purely for detecting very small currents, and when that stage saturates (or the output is larger than some value below saturation) then look at the output of the earlier stage (I assume this is some form of metering application). As you are using Allegro devices, how sensitive are they to nearby magnetic fields? I haven't gone digging in the datasheets and app notes for detailed info as yet, as this project is still in the incubation stage. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --------------------------------- Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist