{"id":71,"date":"2020-08-16T15:10:24","date_gmt":"2020-08-16T15:10:24","guid":{"rendered":"http:\/\/100.26.179.211\/?p=71"},"modified":"2022-01-28T23:43:38","modified_gmt":"2022-01-28T23:43:38","slug":"em-interference-and-xenon-flash-bulbs","status":"publish","type":"post","link":"http:\/\/michaeltsmith.org.uk\/?p=71","title":{"rendered":"EM interference and xenon flash bulbs"},"content":{"rendered":"\n<p>I&#8217;ve started looking at bumblebee flight paths (especially during initial orientation flights from the nest). To this end I&#8217;ve wanted to increase the acquisition frequency of the system.<\/p>\n\n\n\n<p>I found that firing more frequently than about every 1.6s seconds lead to marked decreases in the actual brightness of the flash. Instead I&#8217;ve rebuilt the electronics to allow the flashes to be fired sequentially. I have previously done this but found often the flashes would end up firing together. I assumed my circuit had a short, but I found the same happened again in my new circuit. I experimented for a while adding various capacitors across the supply rail (thinking maybe there was a &#8216;spike&#8217; coming back through the two trigger wires from the flash), with the same thinking I added a reversed diode across those lines to catch any such spike. None of this helped.<\/p>\n\n\n\n<p>I eventually found that spreading the flashes out across my desk helped a lot&#8230; this wasn&#8217;t expected, and suggested the problem was likely to be electromagnetic interference. The flash going off involves considerable current*, which even given the small size of the flash probably will equate to quite a large whole-spectrum EM pulse.<\/p>\n\n\n\n<p>After chatting with helpful people on freenode&#8217;s ##electronics, I tried out tin-foil, and found (as long as each flash &amp; wire was wrapped in its own foil &amp; not touching) the 4 flashes would fire independently.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"1024\" src=\"http:\/\/100.26.179.211\/wp-content\/uploads\/2020\/08\/flashfoil-768x1024.jpeg\" alt=\"\" class=\"wp-image-72\" srcset=\"http:\/\/michaeltsmith.org.uk\/wp-content\/uploads\/2020\/08\/flashfoil-768x1024.jpeg 768w, http:\/\/michaeltsmith.org.uk\/wp-content\/uploads\/2020\/08\/flashfoil-225x300.jpeg 225w, http:\/\/michaeltsmith.org.uk\/wp-content\/uploads\/2020\/08\/flashfoil-1152x1536.jpeg 1152w, http:\/\/michaeltsmith.org.uk\/wp-content\/uploads\/2020\/08\/flashfoil.jpeg 1200w\" sizes=\"auto, (max-width: 706px) 89vw, (max-width: 767px) 82vw, 740px\" \/><figcaption>Quick foil experiment!<\/figcaption><\/figure>\n\n\n\n<p>I&#8217;ll try out using some household build thermal insulation tape to shield the flashes next as that will be a little more tidy. I also found direct sunlight got the black casings quite hot so they will probably benefit from the silver foil for that reason too.<\/p>\n\n\n\n<p>*back of the envelope calculation: If the flash (at 1\/32) is abour 3J over 10us (=300kW) with say, 300V across it, then the current will be on the order of 300kW\/300=1kA.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I&#8217;ve started looking at bumblebee flight paths (especially during initial orientation flights from the nest). To this end I&#8217;ve wanted to increase the acquisition frequency of the system. I found that firing more frequently than about every 1.6s seconds lead to marked decreases in the actual brightness of the flash. Instead I&#8217;ve rebuilt the electronics &hellip; <\/p>\n<p class=\"link-more\"><a href=\"http:\/\/michaeltsmith.org.uk\/?p=71\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;EM interference and xenon flash bulbs&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-71","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=\/wp\/v2\/posts\/71","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=71"}],"version-history":[{"count":1,"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=\/wp\/v2\/posts\/71\/revisions"}],"predecessor-version":[{"id":73,"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=\/wp\/v2\/posts\/71\/revisions\/73"}],"wp:attachment":[{"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=71"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=71"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/michaeltsmith.org.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=71"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}