{"id":958,"date":"2023-01-31T20:20:17","date_gmt":"2023-02-01T01:20:17","guid":{"rendered":"http:\/\/www.paleotechnologist.net\/?p=958"},"modified":"2023-01-31T20:20:22","modified_gmt":"2023-02-01T01:20:22","slug":"components-inductors","status":"publish","type":"post","link":"https:\/\/www.paleotechnologist.net\/?p=958","title":{"rendered":"Components: Inductors"},"content":{"rendered":"\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.paleotechnologist.net\/wp-content\/uploads\/2023\/01\/2023-01-31-20.02.18-1024x768.jpg\" alt=\"\" class=\"wp-image-5044\" srcset=\"https:\/\/www.paleotechnologist.net\/wp-content\/uploads\/2023\/01\/2023-01-31-20.02.18-1024x768.jpg 1024w, https:\/\/www.paleotechnologist.net\/wp-content\/uploads\/2023\/01\/2023-01-31-20.02.18-300x225.jpg 300w, https:\/\/www.paleotechnologist.net\/wp-content\/uploads\/2023\/01\/2023-01-31-20.02.18-768x576.jpg 768w, https:\/\/www.paleotechnologist.net\/wp-content\/uploads\/2023\/01\/2023-01-31-20.02.18-1536x1152.jpg 1536w, https:\/\/www.paleotechnologist.net\/wp-content\/uploads\/2023\/01\/2023-01-31-20.02.18-2048x1536.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Various inductors (chokes and transformers). Ruler and transit token for scale.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">An inductor is probably the simplest electronic component. It is literally a wire, bent into a coil around a core of either air or another substance. Although all real inductors have some resistance (unless made of superconductors), inductors&#8217; usefulness results from their electromagnetic properties &#8212; both as electromagnets and in electronic circuits.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"> Just as a resistor has a characteristic law &#8212; Ohm&#8217;s Law &#8212; that it follows, inductors follow a similar law. (<a href=\"https:\/\/www.allaboutcircuits.com\/textbook\/direct-current\/chpt-15\/inductors-and-calculus\/\" target=\"_blank\" rel=\"noreferrer noopener\">V = L*di\/dt<\/a>)  The difference is, inductors develop a voltage proportional to the <em>change<\/em> in current per unit of time &#8212; not the flow of current itself. This property is at the heart of many interesting, useful circuits that make use of inductors:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Chokes:<\/strong> Most simply, inductors are used to block high-frequency signals and pass lower-frequency ones. So a RL filter, with the inductor in series, would be a low-pass filter. With the inductor in parallel with the load, it would be a high-pass filter.<\/li>\n\n\n\n<li> <strong>Resonant circuits:<\/strong> An inductor\/capacitor pair can form a resonant circuit, suitable for tuning in radio signals of a particular frequency, or generating AC signals as part of an oscillator.<\/li>\n\n\n\n<li><strong>Voltage multiplication:<\/strong> Inductors are often used as the energy-storage elements of switched-mode (buck and\/or boost) power supplies. If current flowing through an inductor is suddenly blocked, a high voltage appears across the inductor, which can be collected in a capacitor.<\/li>\n\n\n\n<li><strong>Transformers:<\/strong> Two magnetically-coupled coils can convert high voltage to high current or vice-versa.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Basic model<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The characteristic equation for inductors is V = L*di\/dt. Voltage across the inductor is proportional to its inductance in henries, times the time derivative of current (in amps per second, which sounds like a natural unit, but measures <em>rate of change<\/em> of the flow of charge.)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">So, inductors oppose changes in current flow. The voltage across an inductor, by Lenz&#8217;s Law, is in the polarity which will oppose the <em>change in<\/em> current flow. If no current is flowing, the voltage will oppose current flow. If the current is decreasing, the energy in the inductor will act to keep the current flowing.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">At DC, inductors are simply wire, and have resistance but no reactance, since di\/dt is zero. With AC, reactance is proportional to frequency &#8212; Xc = 2*pi*f*L.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Inductors are one of the simplest electronic components &#8212; and one of the most useful. <a href=\"https:\/\/www.paleotechnologist.net\/?p=958\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"footnotes":""},"categories":[265,238],"tags":[734,587,586,582,583,736,735],"class_list":["post-958","post","type-post","status-publish","format-standard","hentry","category-components-electronics","category-electronics","tag-choke","tag-coil","tag-inductance","tag-inductor","tag-inductors","tag-reactance","tag-transformer"],"_links":{"self":[{"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=\/wp\/v2\/posts\/958","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=958"}],"version-history":[{"count":5,"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=\/wp\/v2\/posts\/958\/revisions"}],"predecessor-version":[{"id":5045,"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=\/wp\/v2\/posts\/958\/revisions\/5045"}],"wp:attachment":[{"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=958"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=958"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.paleotechnologist.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=958"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}