{"id":9419,"date":"2014-03-19T06:28:57","date_gmt":"2014-03-19T13:28:57","guid":{"rendered":"http:\/\/rustybolt.info\/wordpress\/?p=9419"},"modified":"2014-03-24T06:13:49","modified_gmt":"2014-03-24T13:13:49","slug":"2014-03-19-7-year-long-running-joule-thief","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=9419","title":{"rendered":"2014-03-19 7 Year Long Running Joule Thief"},"content":{"rendered":"<p><a href=\"http:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2014\/03\/IMG_20140319_105651S3.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-medium wp-image-9433\" alt=\"IMG_20140319_105651S3\" src=\"http:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2014\/03\/IMG_20140319_105651S3-300x175.jpg\" width=\"300\" height=\"175\" srcset=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2014\/03\/IMG_20140319_105651S3-300x175.jpg 300w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2014\/03\/IMG_20140319_105651S3.jpg 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>A few months ago I came across a <a href=\"www.YouTube.com\/watch?v=a2SwZvE41Ok\">7 Year Joule Thief \u00a0video<\/a> from Xee2vids on YouTube (link below). \u00a0It&#8217;s a conventional Joule Thief except that the resistor has been increased to 2 megohms, and a 100 pF capacitor has been added from the resistor to ground. \u00a0He calculates that the LED \u00a0should run for 7 years.<\/p>\n<p>I decided to convert one of my conventional Joule Thiefs to this long running Joule Thief. \u00a0But I really don&#8217;t want it to run for 7 years, I just want it to run for a few weeks.<\/p>\n<p>I made the following changes. \u00a0Instead of 2 megohms, I used 100k between the feedback winding and plus 1.5 volts. \u00a0I put a 150 picofarad disk capacitor between the feedback end of the resistor and -1.5v. \u00a0I changed the transistor to SS9014, A very low current, high gain transistor with a current gain of 400 to 1000. \u00a0This would be a poor choice for a conventional Joule Thief because it cannot handle enough current, but for this low current Joule Thief it&#8217;s just fine. \u00a0And this very high gain allows the use of a CdS photocell to turn it off during daylight. \u00a0I soldered the photo cell on the base lead and to ground. \u00a0I connected the circuit to a AAA cell holder.\u00a0 The tiny light green resistor is 100k.\u00a0 The larger 680 ohm resistor was from the previous circuit, and is optional &#8211; it can be zero ohms.<\/p>\n<p>The battery current is about 4 to 5 milliamps at 1.5 volts. \u00a0Assuming the battery capacity is 850 milliamp hours, the run time at five milliamps is 170 hours, which is 7 days. \u00a0But we all know that as the battery gets depleted, the voltage drops and the LED dims. \u00a0But the Joule Thief keeps on running for considerably longer than the rated battery capacity. \u00a0Instead of 7 days it probably will run more like 14 days or even more,\u00a0 just a lot dimmer.\u00a0 And then I added the CdS photocell, which turns it off during daylight, so it should run brightly for at least two weeks.\u00a0 Then it should keep running until the light is no longer adequate, and it&#8217;s time to change the AAA cell.\u00a0 If it&#8217;s in a room where the lights are on in the evening, it will run considerably less than half the time, and the run time should then be a month or more.<\/p>\n<p>LINK:\u00a0www.YouTube.com\/watch?v=a2SwZvE41Ok (ltr O, not zero)<\/p>\n<p>I looked through other videos from Xee2vids and found at least one other JT that uses a 2 Meg resistor and draws very little power. \u00a0One runs from a 10000 uF capacitor charged up to 6V and he said that it would run for 20 or more minutes. \u00a0It really needs a super capacitor of at least 1 farad, or even more.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A few months ago I came across a 7 Year Joule Thief \u00a0video from Xee2vids on YouTube (link below). \u00a0It&#8217;s a conventional Joule Thief except that the resistor has been increased to 2 megohms, and a 100 pF capacitor has been added from the resistor to ground. \u00a0He calculates that the LED \u00a0should run for<a href=\"https:\/\/rustybolt.info\/wordpress\/?p=9419\"> <\/p>\n<p> (Read More&#8230;)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,99],"tags":[],"class_list":["post-9419","post","type-post","status-publish","format-standard","hentry","category-joule-thief-smps-dc-dc","category-optoelectronics"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/9419","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=9419"}],"version-history":[{"count":20,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/9419\/revisions"}],"predecessor-version":[{"id":9421,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/9419\/revisions\/9421"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=9419"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=9419"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=9419"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}