{"id":16482,"date":"2023-04-05T14:26:26","date_gmt":"2023-04-05T13:26:26","guid":{"rendered":"http:\/\/www.crowave.com\/blog\/?p=16482"},"modified":"2023-04-05T14:32:15","modified_gmt":"2023-04-05T13:32:15","slug":"am-fm-mini-headphone-radio","status":"publish","type":"post","link":"https:\/\/www.crowave.com\/blog\/2023\/04\/05\/am-fm-mini-headphone-radio\/","title":{"rendered":"AM\/FM Mini Headphone Radio"},"content":{"rendered":"<p>Danas je nabavljen mali AM\/FM prijemnik specifi\u010dnog dizajna za no\u0161enje na glavi poput slu\u0161alica, s po\u010detka 1980-tih godina.<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_04.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16486\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_04.jpg\" alt=\"\" width=\"1300\" height=\"502\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_04.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_04-768x297.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_05.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16487\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_05.jpg\" alt=\"\" width=\"1300\" height=\"565\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_05.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_05-768x334.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_06.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16488\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_06.jpg\" alt=\"\" width=\"1000\" height=\"1362\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_06.jpg 1000w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_06-768x1046.jpg 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><\/a><\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_01.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16483\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_01.jpg\" alt=\"\" width=\"1300\" height=\"560\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_01.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_01-768x331.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_03.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16485\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_03.jpg\" alt=\"\" width=\"1300\" height=\"548\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_03.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_03-768x324.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>Na\u0161 primjerak nosi oznaku Oppex Model No. 9070, no isti model prijemnika potpisuju i razni drugi proizvo\u0111a\u010di pod svojim nazivima: International HP-1000, Mustang MU-20, AM\/FM Mini Headphone Radio CGM elettronica (Genova) i drugi. Trgova\u010dka marka Oppex mo\u017ee se na\u0107i na ure\u0111ajima potro\u0161a\u010dke elektronike njema\u010dkog uvoznika Hach KG. Naravno, originalno porijeklo ovog na\u0161eg radio prijemnika je Daleki istok.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_02.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16484\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_02.jpg\" alt=\"\" width=\"800\" height=\"442\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_02.jpg 800w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_02-768x424.jpg 768w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_02-450x250.jpg 450w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<hr \/>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center;\"><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_08.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16490\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_08.jpg\" alt=\"\" width=\"1300\" height=\"851\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_08.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_08-768x503.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><em><span style=\"color: #00ffff;\">Komponente su raspore\u0111ene na dvije tiskane plo\u010dice: lijevo je audio poja\u010dalo, a desno su sklopovi prijemnika. \u00a0\u00a0\u00a0<\/span><\/em><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_07.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16489\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_07.jpg\" alt=\"\" width=\"1000\" height=\"932\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_07.jpg 1000w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_07-768x716.jpg 768w\" sizes=\"auto, (max-width: 1000px) 100vw, 1000px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>Audio poja\u010dalo se sastoji od dva komplementarna para tranzistora:<\/p>\n<ul>\n<li><strong>S9014<\/strong> (NPN) i <strong>S9015<\/strong> (PNP) sa maksimalnim kolektorskim vrijednostima 50 V \/ 100 mA<\/li>\n<li><strong>S9012<\/strong> (PNP) i <strong>S9013<\/strong> (NPN) sa maksimalnim kolektorskim vrijednostima 40 V \/ 500 mA<\/li>\n<\/ul>\n<p>Osim toga, pored ja\u010deg (izlaznog) komplementarnog para uo\u010davaju se i dvije diode. Po ovome je posve jasno da se ovdje radi o klasi\u010dnom spoju audio poja\u010dala u AB-klasi sa komplementarnim parom tranzistora u izlaznom protufaznom (push-pull) spoju. S9014 radi kao pretpoja\u010dalo, S9015 je driver poja\u010dalo, a S9012\/S9013 je push-pull izlazni stupanj. Dvije diode slu\u017ee za odre\u0111ivanje bias-napona izlaznog para tranzistora kako bi se reduciralo crossover izobli\u010denje karakteristi\u010dno za \u010distu B-klasu poja\u010dala, a tako\u0111er i za temperaturnu stabilizaciju izlaznih tranzistora preko BE spoja. Iz push-pull stupnja sa S9012\/S9013 ina\u010de se mo\u017ee izvu\u0107i i do 1 W muzi\u010dke snage, no u na\u0161em slu\u010daju sa baterijskim napajanjem od 3 V na slu\u0161alicama impedancije 32 oma dobivamo oko 50 mW izlazne snage (25 mW po slu\u0161alici).<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_09.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16491\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_09.jpg\" alt=\"\" width=\"1300\" height=\"651\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_09.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_09-768x385.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n<p>AM\/FM prijemnik se bazira na pet tranzistora: jedan <strong>S9011<\/strong> i \u010detiri <strong>S9018<\/strong>. Tranzistori S9018 su VF tranzistori koji se uobi\u010dajeno koriste u krugovima VHF FM tunera i AM\/FM MF poja\u010dala radio prijemnika (tranzistna frekvencija min. 700 MHz). Tranzistor S9011 ima ni\u017eu tranzitnu frekvenciju (150 MHz) te isti onda vjerojatno radi u krugu AM oscilatora.<\/p>\n<p>Ono \u0161to zbunjuje kod ovog prijemnika to je samo \u0161est MF transformatora. Uobi\u010dajeno, prijemnici sa pet tranzistora imaju barem sedam MF transformatora \u0161to zna\u010di da je ovdje napravljena neka dodatna u\u0161teda.<\/p>\n<p>Odre\u0111ivanje namjene MF transformatora i sli\u010dnih promjenjivih zavojnica u metalnim oklopima prema bojama nije jednostavno jer boje mogu biti razli\u010dite za razli\u010dite proizvo\u0111a\u010de ili \u010dak i za razli\u010dite radio ure\u0111aje. Za AM oscilatore i AM MF transformatore boje se u velikom broju slu\u010dajeva poklapaju (crvena, \u017euta, bijela, crna), no kod FM MF transformatora, oscilatora i detektora situacija mo\u017ee biti vrlo \u0161arolika. Uobi\u010dajene boje su zelena, plava, sme\u0111a, ljubi\u010dasta, naran\u010dasta, ru\u017ei\u010dasta, no ni\u0161ta ne garantira da se tako\u0111er ne koriste iste boje kao i za AM transformatore kao i neke druge boje. Jednako tako, ove boje koje smo naveli za FM mogu se koristiti i za AM posebice kada je prijemnik predvi\u0111en za rad na vi\u0161e AM opsega. Da stvar bude gora, na MF transformatorima \u0107emo rijetko na\u0107i oznake prema kojima bi istog mogli bilo kako identificirati. Jednako tako u prijemnicima mo\u017eete na\u0107i po boji, izgledu i dimenzijama dva naizgled jednaka MF transformatora, no isti svejedno mogu imati razli\u010dite omjere transformacije i razli\u010dite ulazne i izlazne impedancije.<\/p>\n<p>Prou\u010davaju\u0107i druge konstrukcije sli\u010dnih malih tranzistorskih prijemnika ve\u0107 smo nau\u010dili kako se proizvo\u0111a\u010di slu\u017ee razli\u010ditim trikovima za u\u0161tedu broja komponenti i za raspored raspolo\u017eivih tranzistora na pojedine VF i NF krugove kako bi dobili neki kompromis izme\u0111u proizvodne cijene i kona\u010dne kvalitete prijemnika. Stoga je ovdje bez elektri\u010dne sheme nezahvalno naga\u0111ati o blok shemi na\u0161eg prijemnika. Svakako bi morali raditi mjerenja MF frekvencija na pojedinim MF stupnjevima (10,7 MHz ili 455 kHz) kako bi razlu\u010dili koji MF transformator i koji tranzistor pripada kojem dijelu prijemnika. Naravno, posve je mogu\u0107e da se jedan ili vi\u0161e tranzistora koristi kao zajedni\u010dki za razli\u010dite sklopove kod AM i FM prijema.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center;\"><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_10.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16492\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_10.jpg\" alt=\"\" width=\"1300\" height=\"569\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_10.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_10-768x336.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><em><span style=\"color: #00ffff;\">Crni MF transformator sa diodom pripada izlaznom AM MF transformatoru i AM detektoru (lijevo), a plavi i ru\u017ei\u010dasti transformatori sa dvije diode pripadaju izlaznom FM MF transformatoru i FM ratio-detektoru (desno).<\/span> <\/em><\/p>\n<p>&nbsp;<\/p>\n<p>Ono \u0161to ovdje mo\u017eemo za najve\u0107om sigurnosti utvrditi to su izlazni MF transformatori za AM i FM nakon kojih slijede detektori (demodulatori). Tako je za AM izlazni MF transformator (455 kHz) standardne crne boje i o\u010dekivano odmah pored njega je smje\u0161tena detektorska dioda. Za FM pak je izlazni MF transformator (10,7 MHz) plave boje, nakon kojeg slijedi FM ratio-detektor sa transformatorom ru\u017ei\u010daste boje i odmah pored njega pripadaju\u0107e dvije diode.<\/p>\n<p>Sada nam ostaju na raspolaganju jo\u0161 samo tri MF transformatora. Jedan bi morao biti u krugu samoosciliraju\u0107eg mje\u0161a\u010da za AM (ru\u017ei\u010dasti), a druga dva su AM (\u017euti) i FM (sme\u0111i) MF transformatori. No raspored tranzistora na plo\u010dici je prili\u010dno neobi\u010dan pa je mogu\u0107e da isti imaju dvojaku ulogu: jedan radi kao mje\u0161a\u010d za AM i 1. MF poja\u010dalo za FM, a drugi radi kao 1. MF poja\u010dalo za AM i 2. MF poja\u010dalo za FM. Prema rasporedu tranzistora nije isklju\u010deno da je ovdje radi u\u0161tede komponenti izba\u010den jedan stupanj AM\/FM\u00a0 MF poja\u010danja, dok u postoje\u0107em stupnju MF poja\u010dala rade dva tranzistora (dvostupanjsko poja\u010dalo).<\/p>\n<p>&nbsp;<\/p>\n<hr \/>\n<p>&nbsp;<\/p>\n<p>Kod prou\u010davanja prakti\u010dnih izvedbi malih tranzistorskih superheterodinskih prijemnika (do 10 tranzistora) ve\u0107 smo nailazili na svakakve kombinacije sklopova. Da imamo elektroni\u010dku shemu ovog na\u0161eg AM\/FM Mini Headphone Radio prijemnika zasigurno bi na\u0161li jo\u0161 neko novo inovativno rje\u0161enje da se \u0161to vi\u0161e smanji broj upotrijebljenih komponenti.<\/p>\n<p>Ovaj prijemnik specifi\u010dnog dizajna prona\u0161ao sam na buvljaku i podsjetio me na izloge kioska gdje su se u 1980-tim godinama prodavali takvi i sli\u010dni mali d\u017eepni radio prijemnici. Za jednog mladog zaljubljenika u radio tehniku i elektroniku ti ure\u0111aji su tada svakako izgledali privla\u010dno, no naravno nije uvijek bilo mogu\u0107nosti za njihovu kupnju. Na sre\u0107u, za neke \u017eelje iz mladosti nije nikad kasno da se ispune, barem \u0161to se elektronike ti\u010de \ud83d\ude42<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_12.jpg\" rel=\"lightbox[16482]\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-16495\" src=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_12.jpg\" alt=\"\" width=\"1300\" height=\"1761\" srcset=\"http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_12.jpg 1300w, http:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_12-768x1040.jpg 768w\" sizes=\"auto, (max-width: 1300px) 100vw, 1300px\" \/><\/a><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Danas je nabavljen mali AM\/FM prijemnik specifi\u010dnog dizajna za no\u0161enje na glavi poput slu\u0161alica, s po\u010detka 1980-tih godina. &nbsp; &nbsp; Na\u0161 primjerak nosi oznaku Oppex Model No. 9070, no isti model prijemnika potpisuju i razni drugi proizvo\u0111a\u010di pod svojim nazivima: International HP-1000, Mustang MU-20, AM\/FM Mini Headphone Radio CGM elettronica (Genova) i drugi. Trgova\u010dka marka [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":16493,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":{"0":"post-16482","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-radio","8":"czr-hentry"},"jetpack_featured_media_url":"https:\/\/crowave.com\/blog\/wp-content\/uploads\/2023\/04\/oppex_headphone_radio_11.jpg","_links":{"self":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts\/16482","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/comments?post=16482"}],"version-history":[{"count":2,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts\/16482\/revisions"}],"predecessor-version":[{"id":16496,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/posts\/16482\/revisions\/16496"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/media\/16493"}],"wp:attachment":[{"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/media?parent=16482"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/categories?post=16482"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.crowave.com\/blog\/wp-json\/wp\/v2\/tags?post=16482"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}