I removed the two core coil from the circuit of my previous blog and put the 550 turn coil in its place.\u00a0 In my haste to see how well it worked, I connected the power supply clip leads backwards, so positive was connected to negative, etc.\u00a0 But I really didn’t notice, because it was working.\u00a0 But then as I was working on it, I realized the mistake, and corrected it.\u00a0 But now it wasn’t working.\u00a0 Okay, so it worked with the power backwards but not with it correctly\u00a0 connected.\u00a0 Then I remembered that JFETs can be symmetrical: the source and drain can be interchanged.\u00a0 This must be what’s happening when I connected it backwards.\u00a0 So what I needed to do was reverse one winding to get it to work.<\/p>\n
I unsoldered the fine wires of the feedback winding, and reconnected them the correct way.\u00a0 I turned the power on and it started working.\u00a0 But the LED started to glow at 87 millivolts, which was 6 or 7 higher than the original coil.\u00a0 And the oscillations showed up on the scope at 48 millivolts, about ten mV higher than the original.\u00a0 These are still quite low, but I was disappointed that they were not as good as the original.\u00a0 After all, I spent an hour or two winding all that wire onto the core – and got no benefit for it.<\/p>\n
See the original blog here<\/strong><\/a>.<\/p>\n More on Low V JTs here in Ch. 3<\/strong><\/a>.<\/p>\n Back to experimenting…<\/p>\n","protected":false},"excerpt":{"rendered":" I removed the two core coil from the circuit of my previous blog and put the 550 turn coil in its place.\u00a0 In my haste to see how well it worked, I connected the power supply clip leads backwards, so positive was connected to negative, etc.\u00a0 But I really didn’t notice, because it was working.\u00a0 <\/p>\n (Read More…)<\/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-5912","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\/5912","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=5912"}],"version-history":[{"count":10,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/5912\/revisions"}],"predecessor-version":[{"id":5920,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/5912\/revisions\/5920"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5912"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5912"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5912"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}