{"id":1747,"date":"2012-10-04T20:00:55","date_gmt":"2012-10-04T19:00:55","guid":{"rendered":"https:\/\/www.reenigne.org\/blog\/?p=1747"},"modified":"2012-09-14T22:34:11","modified_gmt":"2012-09-14T21:34:11","slug":"led-strobe-and-spinning-disc","status":"publish","type":"post","link":"https:\/\/www.reenigne.org\/blog\/led-strobe-and-spinning-disc\/","title":{"rendered":"LED strobe and spinning disc"},"content":{"rendered":"<p>My son's <a href=\"http:\/\/www.amazon.com\/dp\/B00008BFZH\">Elenco Snap Circuits Jr. SC-100 toy<\/a> came with a spinning disc that demonstrates stroboscopic behavior when accelerating or decelerating under a fluorescent light. I built my own LED strobe with adjustable frequency and duty cycle to make the effect a bit more visible. In the following video you can see what happens as the duty cycle is adjusted:<\/p>\n<p><object width=\"425\" height=\"344\"><param name=\"movie\" value=\"http:\/\/www.youtube.com\/v\/Z1vcqau980o&hl=en&fs=1\"><\/param><param name=\"allowFullScreen\" value=\"true\"><\/param><param name=\"allowscriptaccess\" value=\"always\"><\/param><embed src=\"http:\/\/www.youtube.com\/v\/Z1vcqau980o&hl=en&fs=1\" type=\"application\/x-shockwave-flash\" allowscriptaccess=\"always\" allowfullscreen=\"true\" width=\"425\" height=\"344\"><\/embed><\/object><\/p>\n<p>The circuit is too simple to show a schematic for - just a LED with current limiting resistor and three potentiometers connected to an Arduino. The clever bit is the <a href=\"https:\/\/github.com\/reenigne\/reenigne\/tree\/master\/strobe\/strobe.ino\">Arduino program<\/a>. Also, because I needed to be able to tune the frequency quite precisely, I used two potentiometers for the frequency - one for coarse adjustments and one for fine. Only the top 6 bits of the coarse potentiometer's measured value are used (otherwise the fine potentiometer would be useless due to the jitter). The remaining 10 bits come from the fine potentiometer, yielding a theoretical 16 bits of frequency resolution, giving a range of about 3.8Hz to 250KHz.<\/p>\n<p>The video would probably come out better if I connected multiple LEDs to the output, but I only had one white LED to hand.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>My son's Elenco Snap Circuits Jr. SC-100 toy came with a spinning disc that demonstrates stroboscopic behavior when accelerating or decelerating under a fluorescent light. I built my own LED strobe with adjustable frequency and duty cycle to make the effect a bit more visible. In the following video you can see what happens as [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,40,30],"tags":[],"class_list":["post-1747","post","type-post","status-publish","format-standard","hentry","category-hardware","category-random","category-science"],"_links":{"self":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/1747","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/comments?post=1747"}],"version-history":[{"count":2,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/1747\/revisions"}],"predecessor-version":[{"id":1810,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/1747\/revisions\/1810"}],"wp:attachment":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/media?parent=1747"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/categories?post=1747"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/tags?post=1747"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}