{"id":120,"date":"2013-02-11T08:23:36","date_gmt":"2013-02-11T07:23:36","guid":{"rendered":"http:\/\/honza.paws.cz\/?p=120"},"modified":"2013-03-10T15:13:18","modified_gmt":"2013-03-10T14:13:18","slug":"fet-prepinacswitch","status":"publish","type":"post","link":"http:\/\/honza.paws.cz\/?p=120","title":{"rendered":"FET p\u0159ep\u00edna\u010d\/switch"},"content":{"rendered":"

A\u010d nejsem elektrotechnicky vzd\u011bl\u00e1n a m\u00e1m mlhavou p\u0159edstavu o funkci sou\u010d\u00e1stek (mlhav\u011bj\u0161\u00ed, ne\u017e bych si p\u0159edstavoval), povedlo se mi vytvo\u0159it elektronick\u00e9 rel\u00e9. Toti\u017e m\u016fj probl\u00e9m je na sv\u011bt\u011b snad jedine\u010dn\u00fd. M\u011b\u0159\u00edm sepnut\u00ed koncov\u00fdch sp\u00edna\u010d\u016f na vzd\u00e1lenost 100 m. Na to u\u017e je pot\u0159eba n\u011bjak\u00fd zdroj, tak\u017ee vezmu autobaterii (jedn\u00e1 se v\u017edy o do\u010dasnou instalaci). Jen\u017ee jemn\u00e1 elektronika p\u0159ipojen\u00e1 k PC by to nejsp\u00ed\u0161 nezvl\u00e1dla nap\u0159\u00edmo a tak vezmu 12 V rel\u00e9 a sp\u00edn\u00e1m s n\u00edm. Zde je rozkol mezi m\u00fdm a b\u011b\u017en\u00fdm u\u017eit\u00edm rel\u00e9. Ni\u017e\u0161\u00edm nap\u011bt\u00edm se obvykle ovl\u00e1d\u00e1 vy\u0161\u0161\u00ed, u m\u011b naopak. A pak m\u00e1te Raspberry Pi, ke kter\u00e9mu pot\u0159ebuji vyv\u00e9st ke GPIO kol\u00edku 3,3 V v p\u0159\u00edpad\u011b, \u017ee je uzav\u0159en 12 V vn\u011bj\u0161\u00ed obvod, nav\u00edc to pot\u0159ebuji co nejrychleji, to mi mechanick\u00e9 rel\u00e9 nezajist\u00ed. Proto\u017ee jsem k Raspberry po\u0159\u00eddil n-kan\u00e1lov\u00fd FET BS107 jako m\u011bni\u010d mezi hladinami 5\u00a0V a 3,3 V pro p\u0159ipojen\u00ed p\u0159\u00edslu\u0161enstv\u00ed. Doufal jsem, \u017ee p\u016fjde ud\u011blat i p\u0159ep\u00edna\u010d, kter\u00fd si p\u0159edstavuji. Dlouho jsem hledal a nic nena\u0161el, a\u017e jsem se jal d\u011blat pokusy a nakonec na to p\u0159i\u0161el. \u0158ekl jsem si, \u017ee tranzistor otev\u00edr\u00e1 nap\u011bt\u00ed na GATE, p\u0159ivedl jsem tam tedy 12 V od sp\u00edna\u010de, k SOURCE jsem p\u0159ipojil spole\u010dnou zem (GND) p\u0159es odpor, m\u011bl jsem tady zrovna n\u011bkolik kousk\u016f 330k nav\u00edc, jist\u011b by to cht\u011blo propo\u010d\u00edtat. Nu a k DRAIN jsem p\u0159ipojil zat\u00edm 5 V, v r\u00e1mci v\u00fdvoje. Nyn\u00ed po stisku tla\u010d\u00edtka sp\u00edna\u010de na 12 V v\u011btvi, jsem multimetrem nam\u011b\u0159il na no\u017ei\u010dce SOURCE k\u00fd\u017een\u00e9 ni\u017e\u0161\u00ed z obou nap\u011bt\u00ed. Po uvoln\u011bn\u00ed tla\u010d\u00edtka tam v\u0161ak z\u016fst\u00e1valo, vzal jsem tedy je\u0161t\u011b jeden 330k rezistor a p\u00edchnul jej mezi GATE a GND s t\u00edm, \u017ee n\u00e1boj \u010di co tam z\u016fst\u00e1v\u00e1 vybije do zem\u011b. Stalo se, a p\u0159ep\u00edna\u010d funguje. Zb\u00fdv\u00e1 jen zjistit, zda by nesta\u010dil n\u011bjk\u00fd levn\u011bj\u0161\u00ed a b\u011b\u017en\u00fd tranzistor, zda je FET opravdu nutn\u00fd, stejn\u011b jako velikosti rezistor\u016f p\u0159ipojen\u00fdch do zem\u011b.<\/p>\n

LED je \u00fam\u00edst\u011bna \u0161patn\u011b, oprava dole. \/ LED is wrong placed, explanation is at the end of article.<\/strong>
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EDIT: Vyzkou\u0161el jsem mnohem levn\u011bj\u0161\u00ed BS170, hlavn\u00ed rozd\u00edl je v maxim\u00e1ln\u00edm nap\u011bt\u00ed 200\u00a0V oproti 60\u00a0V, to v\u0161ak v m\u00e9m p\u0159\u00edpad\u011b v\u016fbec nevad\u00ed. Na GME dostanete datasheet od Philips, ale na prvn\u00ed pohled byly obr\u00e1cen\u00e9 no\u017ei\u010dky Source a Drain, P\u0159i zapojen\u00ed podle Datasheetu mi to neb\u011bhalo, na \u00fadajn\u00e9 Source no\u017ei\u010dce bylo po\u0159\u00e1d nap\u011bt\u00ed. Vsadil jsem pouzdro stejn\u011b jako p\u0159edchoz\u00ed BS107 a funguje, tak jak j\u00e1 o\u010dek\u00e1v\u00e1m, kde je tedy chyba?<\/p>\n

EDIT 10.3.2013: Po sestaven\u00ed zku\u0161ebn\u00ed desky se uk\u00e1zalo, \u017ee pin nastaveny v RPi jako vstupn\u00ed je obda\u0159en velkou impedanc\u00ed a dioda se, dle m\u00e9ho prvotn\u00edho n\u00e1padu, nerozsv\u00edt\u00ed. Sta\u010d\u00ed jednodu\u0161e p\u0159ehodit LED na v\u011btev jdouc\u00ed ze SOURCE do zem\u011b a je po probl\u00e9mech. I p\u0159esto, \u017ee se LED nerozsv\u00edt\u00ed, obvod fungoval dle p\u0159edpoklad\u016f, dioda tam ani b\u00fdt nemus\u00ed, je ur\u010den obsluze pro kontrolu sepnut\u00ed koncov\u00e9ho sn\u00edma\u010de.\"mosfet_switch\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

A\u010d nejsem elektrotechnicky vzd\u011bl\u00e1n a m\u00e1m mlhavou p\u0159edstavu o funkci sou\u010d\u00e1stek (mlhav\u011bj\u0161\u00ed, ne\u017e bych si p\u0159edstavoval), povedlo se mi vytvo\u0159it elektronick\u00e9 rel\u00e9. Toti\u017e m\u016fj probl\u00e9m je na sv\u011bt\u011b snad jedine\u010dn\u00fd. M\u011b\u0159\u00edm sepnut\u00ed koncov\u00fdch sp\u00edna\u010d\u016f na vzd\u00e1lenost 100 m. Na to u\u017e je pot\u0159eba n\u011bjak\u00fd zdroj, tak\u017ee vezmu autobaterii (jedn\u00e1 se v\u017edy o do\u010dasnou instalaci). Jen\u017ee […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[6],"tags":[7,8,9],"_links":{"self":[{"href":"http:\/\/honza.paws.cz\/index.php?rest_route=\/wp\/v2\/posts\/120"}],"collection":[{"href":"http:\/\/honza.paws.cz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/honza.paws.cz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/honza.paws.cz\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/honza.paws.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=120"}],"version-history":[{"count":15,"href":"http:\/\/honza.paws.cz\/index.php?rest_route=\/wp\/v2\/posts\/120\/revisions"}],"predecessor-version":[{"id":127,"href":"http:\/\/honza.paws.cz\/index.php?rest_route=\/wp\/v2\/posts\/120\/revisions\/127"}],"wp:attachment":[{"href":"http:\/\/honza.paws.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=120"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/honza.paws.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=120"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/honza.paws.cz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=120"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}