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Then, I set about sitting down and measuring the value of 30 resistors or so.<\/p>\n Once I had them all measured, I had to pick a set of closely matched resistors. Simply writing all the values down, it’s easy to pick a pair of closely matched resistors, but I needed two sets of eight closely matched resistors. The result was the following Matlab script, which picks the closest set of numbers from a group.<\/p>\n Using this script, I turned my random pile of 30 1% resistors into two sets of 8 resistors matched to better than 0.05%. While the value they are centered around is not exactly 970k\u03a9, the spread of values means that my CMRR does much better than a 1% priced pile of resistors should deliver, and it cost me a lot less than buying sixteen 0.05% matched resistors!<\/p>\n","protected":false},"excerpt":{"rendered":" One problem with choosing closely matched resistors is that 0.1% of 1M\u03a9 is 1k\u03a9. Most multimeters are rated in “digits”, e.g. “4 1\/2 digits”. This means that they can display a range from 0 to 19999. This means that with a ~1M\u03a9 resistor, you can measure \u00b150\u03a9 steps. This is enough to measure … Continue reading “Sorting Resistors”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-114","post","type-post","status-publish","format-standard","hentry","category-tools"],"_links":{"self":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts\/114","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/comments?post=114"}],"version-history":[{"count":5,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts\/114\/revisions"}],"predecessor-version":[{"id":127,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts\/114\/revisions\/127"}],"wp:attachment":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/media?parent=114"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/categories?post=114"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/tags?post=114"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"http:\/\/eequalspi.com\/wp-content\/uploads\/2017\/08\/IMG_1144-e1502062285842-169x300.jpg\")
function [closestVals closestPos] = smallestSet(randomVals, number)\r\n\r\nrandomSize = size(randomVals);\r\n\r\nif(randomSize(2) == 1)\r\n randomVals = randomVals.'\r\nend\r\n\r\nclosestVals = randomVals(1:number);\r\nclosestPos = (1:number);\r\nrange(closestVals)\r\nfor value = randomVals\r\n if(value == -inf)\r\n continue;\r\n end\r\n nearVals = zeros(1,number);\r\n nearPos = zeros(1,number);\r\n distVals = abs(randomVals - value);\r\n for n = 1:number\r\n [minVal minPos] = min(distVals);\r\n nearVals(n) = randomVals(minPos);\r\n nearPos(n) = minPos;\r\n distVals(minPos) = inf;\r\n end\r\n \r\n if(range(nearVals) < range(closestVals))\r\n closestVals = nearVals;\r\n closestPos = nearPos;\r\n end\r\nend<\/pre>\n