{"id":4860,"date":"2012-11-05T15:47:42","date_gmt":"2012-11-05T23:47:42","guid":{"rendered":"http:\/\/rustybolt.info\/wordpress\/?p=4860"},"modified":"2012-11-05T19:26:06","modified_gmt":"2012-11-06T03:26:06","slug":"2012-11-05","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=4860","title":{"rendered":"2012-11-05 Ultra Simple Joule Thief Replication Video (sort of)"},"content":{"rendered":"<p>I received a Google Alert which linked to <a href=\"http:\/\/www.youtube.com\/watch?v=-StrDSMJ7uc\">this Youtube video<\/a> which consisted of about a minute of nothing else but a schematic of a circuit, with a lot of background noise.\u00a0 The circuit consisted of a single transistor with a coil, capacitor and 68 ohm resistor, and of course the LED.\u00a0 I tack soldered the circuit together with the same components, except for the 100 uH choke, which I instead used a 180 uH choke.\u00a0 The transistor is labeled 2N2222, which comes in a metal package, but the picture showed a plastic package, which is actually a PN2222A or MPS2222A.<\/p>\n<p>I set the supply at 1.5V and the LED lit up but not very brightly.\u00a0 The current was about 12 milliamps.\u00a0 I measured the voltage drop across the 68 ohm resistor; it measured 0.8V, more than half the supply voltage.\u00a0 Since the whole supply current goes through this resistor, over half of the power is wasted in this resistor.\u00a0 This makes for a very inefficient Joule Thief.<\/p>\n<p>The frequency meter measured an extremely high 700 kHz, in the middle of the AM broadcast band.\u00a0 This is a bad place to be since it interferes with the radio stations.\u00a0 I have a strong suspicion that since the circuit includes a choke and capacitor, it actually is oscillating as a tuned circuit, not a true Joule Thief where the coil alone is producing a back EMF to light the LED.\u00a0 I cannot confirm this because I still have not found the box where I packed my digital oscilloscope when I moved.\u00a0 I haven&#8217;t even fired up the windoze PC that it was connected to.\u00a0 I opened up some more boxes this weekend so I&#8217;ll eventually get to it.\u00a0 I would assume that if the 180 uH choke was changed to the 100 uH, the frequency would be even closer to the middle of the AM BC band.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I received a Google Alert which linked to this Youtube video which consisted of about a minute of nothing else but a schematic of a circuit, with a lot of background noise.\u00a0 The circuit consisted of a single transistor with a coil, capacitor and 68 ohm resistor, and of course the LED.\u00a0 I tack soldered<a href=\"https:\/\/rustybolt.info\/wordpress\/?p=4860\"> <\/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":[1],"tags":[],"class_list":["post-4860","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/4860","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=4860"}],"version-history":[{"count":7,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/4860\/revisions"}],"predecessor-version":[{"id":4862,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/4860\/revisions\/4862"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4860"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4860"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4860"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}