{"id":11004,"date":"2024-09-25T11:11:54","date_gmt":"2024-09-25T05:41:54","guid":{"rendered":"https:\/\/johnsonfrancis.org\/techworld\/?p=11004"},"modified":"2024-09-25T11:11:56","modified_gmt":"2024-09-25T05:41:56","slug":"checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope","status":"publish","type":"post","link":"https:\/\/johnsonfrancis.org\/techworld\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\/","title":{"rendered":"Checking the 50 Hz hum of alternating current in a loudspeaker, a crude &#8216;oscilloscope&#8217;!"},"content":{"rendered":"<p><iframe loading=\"lazy\" width=\"560\" height=\"315\" src=\"https:\/\/www.youtube.com\/embed\/ka6FbhfFWF8?si=7katmg_Q8yHZpghX\" title=\"YouTube video player\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><br \/>\nI connected a step down transformer to the input of an amplispeaker with a 50K cermet preset potentiometer to listen to the 50 Hz hum of alternating current. The intensity of hum increased gradually when the resistance value of the preset was reduced to half gradually. Of course, I did not attempt reducing it fully for fear of blowing out the input circuit of the amplifier with over 10 V in the output of the step down transformer. I used the same method to check for any hum in the filtered output of the bridge rectifier which I made the other day. I could not hear only a minimal hum. It was a crude method of checking the output waveform short of an oscilloscope!<\/p>\n","protected":false},"excerpt":{"rendered":"<p>I connected a step down transformer to the input of an amplispeaker with a 50K cermet preset potentiometer to listen to the 50 Hz hum of alternating current. The intensity of hum increased gradually when the resistance value of the preset was reduced to half gradually. Of course, I did not attempt reducing it fully [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-11004","post","type-post","status-publish","format-standard","hentry","category-amateur-radio-ham-radio"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Checking the 50 Hz hum of alternating current in a loudspeaker, a crude &#039;oscilloscope&#039;! - Johnson&#039;s Techworld<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/johnsonfrancis.org\/techworld\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Checking the 50 Hz hum of alternating current in a loudspeaker, a crude &#039;oscilloscope&#039;! - Johnson&#039;s Techworld\" \/>\n<meta property=\"og:description\" content=\"I connected a step down transformer to the input of an amplispeaker with a 50K cermet preset potentiometer to listen to the 50 Hz hum of alternating current. The intensity of hum increased gradually when the resistance value of the preset was reduced to half gradually. Of course, I did not attempt reducing it fully [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/johnsonfrancis.org\/techworld\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\/\" \/>\n<meta property=\"og:site_name\" content=\"Johnson&#039;s Techworld\" \/>\n<meta property=\"article:published_time\" content=\"2024-09-25T05:41:54+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2024-09-25T05:41:56+00:00\" \/>\n<meta name=\"author\" content=\"Johnson Francis\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Johnson Francis\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\\\/\"},\"author\":{\"name\":\"Johnson Francis\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/#\\\/schema\\\/person\\\/6201c843e80ccd3578e6196b1d007027\"},\"headline\":\"Checking the 50 Hz hum of alternating current in a loudspeaker, a crude &#8216;oscilloscope&#8217;!\",\"datePublished\":\"2024-09-25T05:41:54+00:00\",\"dateModified\":\"2024-09-25T05:41:56+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\\\/\"},\"wordCount\":135,\"publisher\":{\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/#\\\/schema\\\/person\\\/6201c843e80ccd3578e6196b1d007027\"},\"articleSection\":[\"Amateur Radio (Ham Radio)\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\\\/\",\"url\":\"https:\\\/\\\/johnsonfrancis.org\\\/techworld\\\/checking-the-50-hz-hum-of-alternating-current-in-a-loudspeaker-a-crude-oscilloscope\\\/\",\"name\":\"Checking the 50 Hz hum of alternating current in a loudspeaker, a crude 'oscilloscope'! 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