{"id":1622,"date":"2013-05-23T23:16:27","date_gmt":"2013-05-23T22:16:27","guid":{"rendered":"http:\/\/helpmyphysics.co.uk\/wordpress\/?p=1622"},"modified":"2013-09-22T14:35:00","modified_gmt":"2013-09-22T13:35:00","slug":"inverting-opamp","status":"publish","type":"post","link":"https:\/\/helpmyphysics.co.uk\/wordpress\/?p=1622","title":{"rendered":"Inverting Opamp"},"content":{"rendered":"<p>Here is an example of an operational amplifier. It is in <strong>inverting mode<\/strong><br \/>\nChange the feedback resistor by moving the mouse over the black handle.<br \/>\nClick on it to reset it back to 1000 ohms.<br \/>\nYou can vary the input voltage by clicking the green arrow.<\/p>\n<p>Set the feedback resistor to 4000 ohms.<\/p>\n\n<object classid=\"clsid:D27CDB6E-AE6D-11cf-96B8-444553540000\"\n\t\t\tid=\"fm_opampinv_92692646\"\n\t\t\tclass=\"flashmovie\"\n\t\t\twidth=\"550\"\n\t\t\theight=\"450\">\n\t<param name=\"movie\" value=\"http:\/\/www.helpmyphysics.co.uk\/opampinv.swf\" \/>\n\t<!--[if !IE]>-->\n\t<object\ttype=\"application\/x-shockwave-flash\"\n\t\t\tdata=\"http:\/\/www.helpmyphysics.co.uk\/opampinv.swf\"\n\t\t\tname=\"fm_opampinv_92692646\"\n\t\t\twidth=\"550\"\n\t\t\theight=\"450\">\n\t<!--<![endif]-->\n\t\t\n\t<!--[if !IE]>-->\n\t<\/object>\n\t<!--<![endif]-->\n<\/object>\n<p>The gain of an inverting opamp is given by:<br \/>\n<a href=\"https:\/\/helpmyphysics.co.uk\/wordpress\/wp-content\/uploads\/2013\/05\/daum_equation_1369346549618.png\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/helpmyphysics.co.uk\/wordpress\/wp-content\/uploads\/2013\/05\/daum_equation_1369346549618.png\" alt=\"daum_equation_1369346549618\" width=\"232\" height=\"65\" class=\"aligncenter size-full wp-image-1627\" \/><\/a>.<\/p>\n<p>When the feedback resistor is set to 4000 ohms then the gain of the opamp is:<br \/>\n<a href=\"https:\/\/helpmyphysics.co.uk\/wordpress\/wp-content\/uploads\/2013\/05\/daum_equation_1369346919100.png\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/helpmyphysics.co.uk\/wordpress\/wp-content\/uploads\/2013\/05\/daum_equation_1369346919100.png\" alt=\"daum_equation_1369346919100\" width=\"251\" height=\"65\" class=\"aligncenter size-full wp-image-1629\" \/><\/a><\/p>\n<p>Click the green arrow of the input voltage and note the output voltage.<br \/>\nYou can see that the output voltage is always  multiplied by -4.<\/p>\n<p>If you increase the input voltage too much the output voltage levels off at -15V.<br \/>\nThis is when the amplifier reaches saturation because it cannot give an output voltage larger than the voltage of the supply that works it.<\/p>\n<p>Move the black handle to give the feedback resistor different values and check the gain equation:<br \/>\n<a href=\"https:\/\/helpmyphysics.co.uk\/wordpress\/wp-content\/uploads\/2013\/05\/daum_equation_1369346549618.png\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/helpmyphysics.co.uk\/wordpress\/wp-content\/uploads\/2013\/05\/daum_equation_1369346549618.png\" alt=\"daum_equation_1369346549618\" width=\"232\" height=\"65\" class=\"aligncenter size-full wp-image-1627\" \/><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Here is an example of an operational amplifier. It is in inverting mode Change the feedback resistor by moving the mouse over the black handle. Click on it to reset it back to 1000 ohms. You can vary the input voltage by clicking the green arrow. Set the feedback resistor to 4000 ohms. The gain [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14],"tags":[],"class_list":["post-1622","post","type-post","status-publish","format-standard","hentry","category-higher-physics"],"_links":{"self":[{"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1622","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1622"}],"version-history":[{"count":9,"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1622\/revisions"}],"predecessor-version":[{"id":1633,"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1622\/revisions\/1633"}],"wp:attachment":[{"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1622"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1622"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/helpmyphysics.co.uk\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}