{"id":507,"date":"2010-10-27T15:42:51","date_gmt":"2010-10-27T19:42:51","guid":{"rendered":"http:\/\/embedded-lab.com\/blog\/?p=507"},"modified":"2012-07-30T09:29:32","modified_gmt":"2012-07-30T13:29:32","slug":"a-simple-idea-of-making-a-digitally-controlled-variable-power-supply","status":"publish","type":"post","link":"https:\/\/embedded-lab.com\/blog\/a-simple-idea-of-making-a-digitally-controlled-variable-power-supply\/","title":{"rendered":"A simple idea of making a digitally controlled variable power supply."},"content":{"rendered":"<p>A variable power supply is a very useful tool for designing and testing electronics circuit. There are varieties of adjustable regulator IC&#8217;s available to generate a variable DC power supply. They normally use a two-resistor feedback network at the output to control the output voltage. If one of the resistor is replaced by a potentiometer, the output voltage can be easily adjusted as required. LM350 is one of such adjustable regulators that is capable of supplying in excess of 3A over a 1.2V to 33V output range, and is very easy to use. It requires only 2 external resistors to set the output voltage (shown below). Read the <a href=\"http:\/\/www.national.com\/profile\/snip.cgi\/openDS=LM350\" target=\"_blank\"><strong>datasheet<\/strong><\/a> for more details on LM350. This project also uses an LM350 regulator with a microcontroller to control the output voltage.<\/p>\n<p style=\"text-align: center;\"><a rel=\"attachment wp-att-509\" href=\"http:\/\/embedded-lab.com\/blog\/?attachment_id=509\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-509 aligncenter\" title=\"LM350\" src=\"http:\/\/embedded-lab.com\/blog\/wp-content\/uploads\/2010\/10\/LM350.png\" alt=\"\" width=\"538\" height=\"488\" srcset=\"https:\/\/embedded-lab.com\/blog\/wp-content\/uploads\/2010\/10\/LM350.png 538w, https:\/\/embedded-lab.com\/blog\/wp-content\/uploads\/2010\/10\/LM350-496x450.png 496w\" sizes=\"auto, (max-width: 538px) 100vw, 538px\" \/><\/a><\/p>\n<p>The role of the microcontroller in this project is to select an appropriate resistor for R2 from a resistor bank to control the output voltage. There are 5 resistors in the bank each of which is controlled by a seperate I\/O pin from a microcontroller. The microcontroller turns a bipolar junction transistor ON and OFF to connect and disconnect a resistor across the R2 terminal points. The 5 individual resistors, seperately controlled by the microcontroller, can give rise to 32 different equivalent resistance values for R2, which means 32 different output voltages.<\/p>\n<p style=\"text-align: center;\"><a rel=\"attachment wp-att-508\" href=\"http:\/\/embedded-lab.com\/blog\/?attachment_id=508\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-508 aligncenter\" title=\"MC_ Power_Supply\" src=\"http:\/\/embedded-lab.com\/blog\/wp-content\/uploads\/2010\/10\/MC_-Power_Supply.jpg\" alt=\"\" width=\"480\" height=\"272\" \/><\/a><\/p>\n<p style=\"text-align: left;\">\n<table style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td><script type=\"text\/javascript\">\/\/ <![CDATA[\n   google_ad_client = \"pub-3251335376149574\"; \/* Embedded-Lab_Blog_468x15, created 10\/1\/10 *\/ google_ad_slot = \"5007918417\"; google_ad_width = 468; google_ad_height = 15;\n\/\/ ]]><\/script><br \/>\n<script src=\"http:\/\/pagead2.googlesyndication.com\/pagead\/show_ads.js\" type=\"text\/javascript\">\n<\/script><\/td>\n<td><a href=\"http:\/\/www.electronics-lab.com\/projects\/power\/020\/index.html\" target=\"_blank\"><strong>Read More<\/strong><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"<p>A variable power supply is a very useful tool for designing and testing electronics circuit. There are varieties of adjustable regulator IC&#8217;s available to generate a variable DC power supply. They normally use a two-resistor feedback network at the output to control the output voltage. If one of the resistor is replaced by a potentiometer, the output voltage can be easily adjusted as required. LM350 is one of such adjustable regulators that is capable of supplying in excess of 3A over a 1.2V to 33V output range, and is very easy to use. It requires only 2 external resistors to<\/p>\n","protected":false},"author":2,"featured_media":508,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[30],"tags":[63,64],"class_list":["post-507","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-power-supply","tag-lm350","tag-variable-power-supply"],"_links":{"self":[{"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/posts\/507","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/comments?post=507"}],"version-history":[{"count":6,"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/posts\/507\/revisions"}],"predecessor-version":[{"id":995,"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/posts\/507\/revisions\/995"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/media\/508"}],"wp:attachment":[{"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/media?parent=507"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/categories?post=507"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/embedded-lab.com\/blog\/wp-json\/wp\/v2\/tags?post=507"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}