{"id":12011,"date":"2017-05-21T19:22:42","date_gmt":"2017-05-22T02:22:42","guid":{"rendered":"https:\/\/rustybolt.info\/wordpress\/?p=12011"},"modified":"2017-06-08T23:25:21","modified_gmt":"2017-06-09T06:25:21","slug":"2017-05-21-tbd","status":"publish","type":"post","link":"https:\/\/rustybolt.info\/wordpress\/?p=12011","title":{"rendered":"2017-05-21 22-120 Power Schematic Errors"},"content":{"rendered":"<p>Posted to FB group 2017 June 8, then a copy here.<\/p>\n<p>I found this Radio Shack power supply on Bama.edebris.com. &nbsp;Looks like someone drew it up. &nbsp;I found a few boo-boos, one being the LED having a 100k current limiting resistor. &nbsp;It&#8217;s not going to be bright.<\/p>\n<p>I wonder if BK1 thermal breaker is capable of interrupting &nbsp;the current before the transistor(s) burn out. &nbsp;BK1 also causes a voltage drop so it contributes to poor regulation.<\/p>\n<p>The drawing is somewhat confusing. &nbsp;R2 and C3 should be to the left of Q1. &nbsp;etc&#8230;<\/p>\n<p>I also noticed that it says the T1 secondary is 25 volts. &nbsp;That means Q2 will have to dissipate an excessive amount of power in order to supply 2.5 amps. &nbsp;It also means C1 will have a lot more than its rated 25VDC, and will probably self destruct.<\/p>\n<p>It looks to me like the Q1 PNP is bass ackwards, so I don&#8217;t think this schematic is ready for prime time.<\/p>\n<p><a href=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2017\/06\/IMG_1496987024351.jpg\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2017\/06\/IMG_1496987024351.jpg\" alt=\"\" class=\"wp-image-12096 alignnone size-full\" width=\"1080\" height=\"735\" srcset=\"https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2017\/06\/IMG_1496987024351.jpg 1080w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2017\/06\/IMG_1496987024351-300x204.jpg 300w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2017\/06\/IMG_1496987024351-768x523.jpg 768w, https:\/\/rustybolt.info\/wordpress\/wp-content\/uploads\/2017\/06\/IMG_1496987024351-1024x697.jpg 1024w\" sizes=\"auto, (max-width: 1080px) 100vw, 1080px\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Posted to FB group 2017 June 8, then a copy here. I found this Radio Shack power supply on Bama.edebris.com. &nbsp;Looks like someone drew it up. &nbsp;I found a few boo-boos, one being the LED having a 100k current limiting resistor. &nbsp;It&#8217;s not going to be bright. I wonder if BK1 thermal breaker is capable<a href=\"https:\/\/rustybolt.info\/wordpress\/?p=12011\"> <\/p>\n<p> (Read More&#8230;)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[263,25],"tags":[],"class_list":["post-12011","post","type-post","status-publish","format-standard","hentry","category-errors","category-power-supplies"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/12011","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=12011"}],"version-history":[{"count":3,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/12011\/revisions"}],"predecessor-version":[{"id":12099,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/12011\/revisions\/12099"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12011"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=12011"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=12011"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}