{"id":869,"date":"2012-01-20T14:10:00","date_gmt":"2012-01-20T22:10:00","guid":{"rendered":"http:\/\/rustybolt.info\/wordpress\/?p=869"},"modified":"2012-03-14T18:54:47","modified_gmt":"2012-03-15T01:54:47","slug":"2012-01-20","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=869","title":{"rendered":"2012-01-20 Wien Bridge Oscillator, Audio Generator"},"content":{"rendered":"<p><a href=\"http:\/\/rustybolt.info\/wordpress\/?attachment_id=885\" rel=\"attachment wp-att-885\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-medium wp-image-885\" title=\"WienBrOsc-3xistor\" src=\"http:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WienBrOsc-3xistor-206x300.gif\" alt=\"\" width=\"206\" height=\"300\" srcset=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WienBrOsc-3xistor-206x300.gif 206w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WienBrOsc-3xistor-705x1024.gif 705w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WienBrOsc-3xistor.gif 767w\" sizes=\"auto, (max-width: 206px) 100vw, 206px\" \/><\/a><a href=\"http:\/\/rustybolt.info\/wordpress\/?attachment_id=892\" rel=\"attachment wp-att-892\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-medium wp-image-892\" title=\"WBO-JF10ZL\" src=\"http:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WBO-JF10ZL-300x234.gif\" alt=\"\" width=\"300\" height=\"234\" srcset=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WBO-JF10ZL-300x234.gif 300w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WBO-JF10ZL-1024x800.gif 1024w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/01\/WBO-JF10ZL.gif 1570w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>The Wien Bridge Oscillator (sometimes mistakenly misspelled Wein) uses negative feedback to generate a very pure sine wave.\u00a0 The circuit can generate a sine with distortion so low it is difficult to measure.\u00a0 The schematic I\u00b4ve attached does not necessarily have such very low distortion, but it is simple &#8211; three transistors &#8211; and generates a nice sine wave for doing audio work. You can find out <a href=\"http:\/\/en.wikipedia.org\/wiki\/Wien_bridge_oscillator\">how this circuit works on Wikipedia<\/a>.<\/p>\n<p>This circuit uses a #385 lamp in the negative feedback loop, to stabilize the oscillation point.\u00a0 As the output becomes greater, the higher power is fed back through R5, R6 and C3 to the lamp and it gets a little higher in resistance.\u00a0 The higher resistance reduces the gain of Q1 and stabilizes the oscillation point.<\/p>\n<p>Nowadays with the proliferation of LEDs, lamps are getting harder to find.\u00a0 I have seen Chicago Miniature lamps for under a dollar in the Mouser online catalog, <a href=\"http:\/\/www.mouser.com\/catalog\/catalogUSD\/644\/116.pdf\">P. 116 <\/a>(.PDF; if this has expired, go to mouser.com and search for CM385 lamp).\u00a0 The filament never gets hot enough to burn out so no socket is needed &#8211; just solder it in &#8211; and the lamp will never have to be replaced.\u00a0 You could also use the CM7009 which has wire leads.<\/p>\n<p>If you don\u00b4t like to use a lamp, there is another version from a Japanese ham, JF1ozl.\u00a0 This uses a FET to control the feedback.<\/p>\n<p>Error!\u00a0 <a href=\"http:\/\/www.eeweb.com\/blog\/circuit_projects\/low-frequency-wien-bridge-oscillator\">This circuit<\/a> is NOT a Wien Bridge Oscillator, it is a Phase Shift Oscillator.<\/p>\n<p>Back to experimenting&#8230;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The Wien Bridge Oscillator (sometimes mistakenly misspelled Wein) uses negative feedback to generate a very pure sine wave.\u00a0 The circuit can generate a sine with distortion so low it is difficult to measure.\u00a0 The schematic I\u00b4ve attached does not necessarily have such very low distortion, but it is simple &#8211; three transistors &#8211; and generates<a href=\"https:\/\/rustybolt.info\/wordpress\/?p=869\"> <\/p>\n<p> (Read More&#8230;)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,6,17],"tags":[],"class_list":["post-869","post","type-post","status-publish","format-standard","hentry","category-audio","category-electronics","category-meters-and-test-equipment"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/869","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=869"}],"version-history":[{"count":13,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/869\/revisions"}],"predecessor-version":[{"id":871,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/869\/revisions\/871"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=869"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=869"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=869"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}