{"id":2872,"date":"2012-05-21T08:29:11","date_gmt":"2012-05-21T15:29:11","guid":{"rendered":"http:\/\/rustybolt.info\/wordpress\/?p=2872"},"modified":"2013-02-06T18:55:01","modified_gmt":"2013-02-07T02:55:01","slug":"2012-05-21-air-core-joule-thief","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=2872","title":{"rendered":"2012-05-21 &#8216;Toroid Free&#8217; Air Core Joule thief"},"content":{"rendered":"<p><a href=\"http:\/\/rustybolt.info\/wordpress\/?attachment_id=2874\" rel=\"attachment wp-att-2874\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-medium wp-image-2874\" title=\"DSC_0041S4\" src=\"http:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/05\/DSC_0041S4-300x224.jpg\" alt=\"\" width=\"300\" height=\"224\" srcset=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/05\/DSC_0041S4-300x224.jpg 300w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/05\/DSC_0041S4.jpg 802w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>We don&#8217;t need no stinkin&#8217; toroids!\u00a0 Just wind 15 to 20 feet of twisted pair (this wire was from cat5e cable) onto something round, like a C or AA cell.\u00a0 Then slide it off and tie it up in 3 or 4 places with some thread, twine, dental floss, piece of wire, or tape.\u00a0 The inductance is under 100 microhenrys but it works okay.<\/p>\n<p>The typical cat5e cable uses 23 AWG solid conductor wire, which has about 20 milliohms per foot.\u00a0 Fifteen feet adds up to about 300 milliohms, or a little less than a third of an ohm.\u00a0 That&#8217;s not too high for a JT, but I prefer to keep it to less than 1\/4 ohm.\u00a0 Lower resistance means less losses and higher efficiency.<\/p>\n<p><a href=\"http:\/\/rustybolt.info\/wordpress\/?attachment_id=6153\" rel=\"attachment wp-att-6153\"><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-medium wp-image-6153\" title=\"DSCN1122s\" src=\"http:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/05\/DSCN1122s-300x223.jpg\" alt=\"\" width=\"300\" height=\"223\" srcset=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/05\/DSCN1122s-300x223.jpg 300w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2012\/05\/DSCN1122s.jpg 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>This is a picture of a Supercharged Joule Thief taken in March, 2009.\u00a0 It also uses an air core coil.\u00a0 With the lower inductance, the SJT can run at much higher frequencies, close to or in the AM broadcast band.\u00a0 It&#8217;s a good idea to check to make sure your SJT isn&#8217;t broadcasting in the AM band.<\/p>\n<p>Back to experimenting&#8230;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>We don&#8217;t need no stinkin&#8217; toroids!\u00a0 Just wind 15 to 20 feet of twisted pair (this wire was from cat5e cable) onto something round, like a C or AA cell.\u00a0 Then slide it off and tie it up in 3 or 4 places with some thread, twine, dental floss, piece of wire, or tape.\u00a0 The<a href=\"https:\/\/rustybolt.info\/wordpress\/?p=2872\"> <\/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],"tags":[],"class_list":["post-2872","post","type-post","status-publish","format-standard","hentry","category-joule-thief-smps-dc-dc"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/2872","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=2872"}],"version-history":[{"count":14,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/2872\/revisions"}],"predecessor-version":[{"id":2877,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/2872\/revisions\/2877"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2872"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2872"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2872"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}