{"id":682,"date":"2008-11-19T12:18:55","date_gmt":"2008-11-19T19:18:55","guid":{"rendered":"http:\/\/mightyohm.com\/blog\/?p=682"},"modified":"2015-09-26T11:11:11","modified_gmt":"2015-09-26T18:11:11","slug":"help-identify-this-mystery-component","status":"publish","type":"post","link":"https:\/\/mightyohm.com\/blog\/2008\/11\/help-identify-this-mystery-component\/","title":{"rendered":"Help identify this mystery component!"},"content":{"rendered":"<p><a href=\"http:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/speaker-thing.jpg\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"683\" data-permalink=\"https:\/\/mightyohm.com\/blog\/2008\/11\/help-identify-this-mystery-component\/speaker-thing\/\" data-orig-file=\"https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/speaker-thing.jpg\" data-orig-size=\"497,500\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"Mystery Component\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/speaker-thing.jpg\" class=\"alignnone size-full wp-image-683\" title=\"Mystery Component\" src=\"http:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/speaker-thing.jpg\" alt=\"\" width=\"497\" height=\"500\" srcset=\"https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/speaker-thing.jpg 497w, https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/speaker-thing-150x150.jpg 150w, https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/speaker-thing-298x300.jpg 298w\" sizes=\"auto, (max-width: 497px) 100vw, 497px\" \/><\/a><\/p>\n<p>The vintage telephone speaker I used for my <a href=\"http:\/\/mightyohm.com\/blog\/2008\/11\/bluetooth-handset-hack\/\">Bluetooth Handset<\/a> project has a mysterious component wired across it&#8217;s terminals, as shown above (it&#8217;s the black cylinder with two leads on the upper left).\u00a0 The component measures as an open circuit on my DMM, but obviously it has some hidden function.<\/p>\n<p>So far my guesses are:<\/p>\n<ul>\n<li>A lightning arrestor\/spark gap or back to back diodes that protect the person using the phone from strikes or other high voltage on the line<\/li>\n<li>Some sort of lowpass filter to keep you from hearing otherwise audible tones used for signaling<\/li>\n<li>A device that keeps the high voltage ring signal from damaging the speaker<\/li>\n<\/ul>\n<p>I found a <a href=\"http:\/\/www.porticus.org\/bell\/images\/503b_md_schematic.gif\">schematic<\/a> at the <a href=\"http:\/\/www.porticus.org\/bell\/bell.htm\">Bell System Memorial<\/a> that shows a symbol for the device, but I don&#8217;t recognize it.<\/p>\n<p><a href=\"http:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/phone_schematic_crop.jpg\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"684\" data-permalink=\"https:\/\/mightyohm.com\/blog\/2008\/11\/help-identify-this-mystery-component\/phone_schematic_crop\/\" data-orig-file=\"https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/phone_schematic_crop.jpg\" data-orig-size=\"561,414\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"Schematic\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/phone_schematic_crop.jpg\" class=\"alignnone size-medium wp-image-684\" title=\"Schematic\" src=\"http:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/phone_schematic_crop-300x221.jpg\" alt=\"\" width=\"300\" height=\"221\" srcset=\"https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/phone_schematic_crop-300x221.jpg 300w, https:\/\/mightyohm.com\/blog\/wp-content\/uploads\/2008\/11\/phone_schematic_crop.jpg 561w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>Does anyone know what this thing is and what it&#8217;s for?<\/p>\n<p><a href=\"http:\/\/www.flickr.com\/photos\/mightyohm\/3039193885\/\">We&#8217;re also having a discussion about it on flickr.<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The vintage telephone speaker I used for my Bluetooth Handset project has a mysterious component wired across it&#8217;s terminals, as shown above (it&#8217;s the black cylinder with two leads on the upper left).\u00a0 The component measures as an open circuit on my DMM, but obviously it has some hidden function. So far my guesses are: &hellip; <a href=\"https:\/\/mightyohm.com\/blog\/2008\/11\/help-identify-this-mystery-component\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Help identify this mystery component!<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[5],"tags":[101,501,102,60,104],"class_list":["post-682","post","type-post","status-publish","format-standard","hentry","category-electronics","tag-bluetooth","tag-electronics","tag-handset","tag-mysterious","tag-telephone"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/pioCd-b0","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":668,"url":"https:\/\/mightyohm.com\/blog\/2008\/11\/bluetooth-handset-hack\/","url_meta":{"origin":682,"position":0},"title":"Bluetooth Handset Hack","author":"Jeff","date":"November 18, 2008","format":false,"excerpt":"Kylie recently gave me an old, broken Motorola HS820 bluetooth headset.\u00a0 The headset suffered from a defective microphone that resulted in extremely low volume on outgoing audio, even though everything else worked fine. Upon receiving it, I proceeded to rip the headset apart, interested to see what was inside.\u00a0 I\u2026","rel":"","context":"In &quot;Projects&quot;","block_context":{"text":"Projects","link":"https:\/\/mightyohm.com\/blog\/category\/projects-2\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/mightyohm.com\/blog\/wp-content\/uploads\/2009\/10\/retro_wireless_handset.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":3005,"url":"https:\/\/mightyohm.com\/blog\/2010\/08\/bluetooth-headset-handgun\/","url_meta":{"origin":682,"position":1},"title":"Bluetooth Headset inside a [toy] Handgun","author":"Jeff","date":"August 3, 2010","format":false,"excerpt":"MayorMike,\u00a0inspired by the article I wrote for Make vol. 20 (Retro Wireless Handset), stuck a bluetooth headset in a plastic toy gun to create his\u00a0Handgun Bluetooth Earpiece Project. \u00a0The best part - the earphone is located at the end of the barrel, so to answer a call, you stick it\u2026","rel":"","context":"In &quot;Electronics&quot;","block_context":{"text":"Electronics","link":"https:\/\/mightyohm.com\/blog\/category\/electronics\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/mightyohm.com\/blog\/wp-content\/uploads\/2010\/08\/bluetooth-handgun-mike-haeg.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2501,"url":"https:\/\/mightyohm.com\/blog\/2009\/10\/retro-wireless-handset-in-make-magazine\/","url_meta":{"origin":682,"position":2},"title":"Retro Wireless Handset in Make: Magazine","author":"Jeff","date":"October 28, 2009","format":false,"excerpt":"Volume 20 of Make: magazine, which hits newsstands on November 15th, includes an article I wrote about DIY Telephony titled \"Retro Wireless Handset.\" The article is based on my Bluetooth Handset Hack and includes additional illustrations and step by step instructions to help you build one of your own. If\u2026","rel":"","context":"In &quot;Electronics&quot;","block_context":{"text":"Electronics","link":"https:\/\/mightyohm.com\/blog\/category\/electronics\/"},"img":{"alt_text":"DIY Telephony: Retro Wireless Handset","src":"https:\/\/i0.wp.com\/www.mightyohm.com\/blog\/wp-content\/uploads\/2009\/10\/retro_wireless_handset.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2794,"url":"https:\/\/mightyohm.com\/blog\/2010\/01\/samsung-wep470-bluetooth-headset-pics\/","url_meta":{"origin":682,"position":3},"title":"Samsung WEP470 Bluetooth Headset Pics","author":"Jeff","date":"January 28, 2010","format":false,"excerpt":"Bill Owens recently shot a couple photos of the Samsung WEP470 Bluetooth headset, aka the $3 Woot Headset. This headset looks like a great platform for hacking, but to my knowledge noone has turned one into a Retro Wireless Handset yet... There is some more info about the WEP470 in\u2026","rel":"","context":"In &quot;Electronics&quot;","block_context":{"text":"Electronics","link":"https:\/\/mightyohm.com\/blog\/category\/electronics\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/mightyohm.com\/blog\/wp-content\/uploads\/2010\/01\/4263517697_bbb0ac9639_b-336x500.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2960,"url":"https:\/\/mightyohm.com\/blog\/2010\/06\/maker-faire-retro-bluetooth-handset-talk-on-ustream\/","url_meta":{"origin":682,"position":4},"title":"Maker Faire Retro Bluetooth Handset Talk on Ustream","author":"Jeff","date":"June 2, 2010","format":false,"excerpt":"I didn't know at the time that I was being recorded, but here's a somewhat low quality video of the Retro Bluetooth Handset talk I gave on Sunday of the 2010 Bay Area Maker Faire. The talk starts about 7 minutes into the video, so skip ahead unless you want\u2026","rel":"","context":"In &quot;Events&quot;","block_context":{"text":"Events","link":"https:\/\/mightyohm.com\/blog\/category\/events\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2566,"url":"https:\/\/mightyohm.com\/blog\/2009\/11\/help-is-available-on-the-discussion-forums\/","url_meta":{"origin":682,"position":5},"title":"Help is available on the Discussion Forums!","author":"Jeff","date":"November 11, 2009","format":false,"excerpt":"Do you have a question about the Wifi Radio project or want help making your own Bluetooth Handset? Try asking over at the discussion forums! If you haven't seen them before, be sure to check them out!","rel":"","context":"In &quot;Amateur Radio&quot;","block_context":{"text":"Amateur Radio","link":"https:\/\/mightyohm.com\/blog\/category\/amateur-radio\/"},"img":{"alt_text":"Flathead","src":"https:\/\/i0.wp.com\/mightyohm.com\/files\/flickr\/3972724969_2ae5b52cc8.jpg?resize=350%2C200","width":350,"height":200},"classes":[]}],"_links":{"self":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts\/682","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/comments?post=682"}],"version-history":[{"count":2,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts\/682\/revisions"}],"predecessor-version":[{"id":686,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/posts\/682\/revisions\/686"}],"wp:attachment":[{"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/media?parent=682"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/categories?post=682"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mightyohm.com\/blog\/wp-json\/wp\/v2\/tags?post=682"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}