This is a multi-part message in MIME format. ------=_NextPart_000_01FE_01CAD184.CACC5F00 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit > You are exceeding the common-mode range of the opamp by having > 10v/2 going into each input. Bob, do I have an issue with this circuit, bearing in mind that the meter now zeroes and the output (from subsequent stages) is a linear 4V / 1000rpm, with no baseline offset ? ------=_NextPart_000_01FE_01CAD184.CACC5F00 Content-Type: image/gif; name="meter_amplifier.gif" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="meter_amplifier.gif" R0lGODlhZQGNAIAAAAAAAP///ywAAAAAZQGNAAAC/oyPqcvtD6OctNqLs968+w+G4kiW5omm6sq2 7gvH8kzX9o3n+s73/g8MCofEovGITCqXzGYHgABID1Ko84rNrqYGawDq9WrH5PIFTE2Hv1Wz+w1P d9X0efyOd67n633+D0jkh8YnF3iIuDP4VceY+Ag5I9bWxeUXiZmpucnZ6fkJGio6SlpqqjV5qrqq kMr6quoKOzsqS3tbVqW7y9sb1QvMhTscJHYWRWFMvKyjXGEL4cw8TSM9Af1gTb3toh2B7eDNPY4i XmJOni6CPsKu/s7hHiIPX29B/4Fvvx8do88PcMG/eAELbhh40KDCYzAQLtznMEPEh/D0TbIkYSJF /kUJjFmhxMaSMElnFqHTuDGHxzCEHMlCKfGeo5mEvMFMaWMlFY8z7fT0h8HkT4E4UXVk1FKkMJAk GdJk861oFp5oeCK7BNRpn6GtpGKhivToVUMyLBqq2s+rHrEfn271WTbor7ZckaltssulHZB8R8Zt eLfozWuBceJzJm8wmYt0yQLe2RiuKb/9wGZUjEqoXX+aHZcKBvrsWdCUOSWVg7Xb072eP/9rWSgc ZqM+G88mXDs3K4SIo9YSHbsa8LDrSBs/zivri9tfh8O+HFqr6MHMxS5XHmpRawa6ojFNu1pyvhbV uWMHxdh6g+/XSneFrB5E+e0p5r8n5/6e/Wfc/qknhF8XfeXgd1N+f3VloFMlTZfNeczMtp9v9yWY TEyaSROhgLNQGE+G65n3yxP/uRUgc91ttox9HhLFYke8jdiHNiaCmKJqNWC43msw0mGNf+Jp6ImM j0kSTDaH7VhIj+1ApsyKSjwHJEE0zsUhCWCc6CJ/GqSnV4ut0JMXigF+AuWYHth0n5nntIfbdeZx CI5Vk3F1mzhNirnFM+asqGQlDToXnyhY1ZmRi1iSt2A4DjqWX4+UOYlEmFHGVCiKHr7Wp1xpKjrl Tl5WSoqcEGoJ16UHNVklgkfZ6Z6jgYL322aYgWnpkFsihxygleDKXpY//rnhmlodiuita1rG/p+k IdJKi2I64oDpgJu26Z1MzS5J6Q2HQaopm9TmaEuvjG7KZUgAqqDseKeKy0JqAnGbbTIngfeRdp/e 6Wlub6mpLr/yivhruxqmykO0wEZ1WpJ8eZZKZ6ehhRGxpGoksXQkpesnvFueCm6bJtWkG54Ou1Uv HyB3O1HFFh+ImLuCPMErjoDSta/IDAaXMHGRyZZcwPKyO3HMQucqmV8ax5voiCGfXDPDNxMH9Vs7 f2hdygQDy23LnxphsJSy1hFZbxM28nC+TIM6nNcA+2uCTp1ynXSHCwNIM550znUuJTGy5i++bBf7 t5X5UulLES77GknKXwJdlsoCXx3pwEdr/nvmwTmpxCrG82wtk+ZTTD6V5Tdm91OZFf64FDVoqpQE 40wKrWtIMTMq5+KgD2EntHdE9Jzp4mo97aRBwipcHIoHT5/bnAdumoRNGb9obavbvpvzRuqt96tv m8Hnh3ASHyranOIMlZ/Wv9F9f9R+d7sQ8zr/MEvio6909uML7jOZ3/Znf1hogU8/iXSGaueAHCbc kTuaZO9/99udhW4mJMGQikY7g5jooLcxfY2pfZlgFgWLxrftvYxu8XmRviIolW1NqXchRFykBlg6 JPlve1zioBuehb8n3S08wvtgkjiXuuC8YyAGNNIVxJYaE+6qheO6EHQ+9y6W1GtuGDQW/sxCp54y pe9rPzzdUPb1EhtiS25BKeIPagc1u+WJi0jxIBqzKMQA5sN1jsOL3WSGHaEkZlwEfCP3ChgdOSoL j26aWeAGRcAYOtAwDqph/qqmPWyIcR0SLGTbnMZEv8FhkojIUHmkuBSlYER7i6mkjbzCSSCkih1b NGX1vje/NaYwWOZL5AXRpZZUntGFpERefXJJS14+soebQ+XQjonMZCqTV7TrpTMvWZjqoe5wvpRW NGMhO62xMnrXJF3+VsnNbupvmLBEVyDFOU493RKdKelaNa3UM3aih2PClGc7YRZP8pjRnnjgDar4 iUoB2hKgFFFhAwn6kMTsCaGMvMz+WBhqkCv16mq6hOgYzvkuBVl0iCIsn0Y3mg5CDq5bIFWHSPdJ zJIGs2oUUylHiYLSd7p0GBjy0UzHsZ+K3lSHAtspN3Lq058uE3ZBLapRj4rUpCp1qbQoAAAAOw== ------=_NextPart_000_01FE_01CAD184.CACC5F00 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist ------=_NextPart_000_01FE_01CAD184.CACC5F00--