Bobina este realizata prin infasurarea unui conductor izolai pe un suport de material izolant (ceramica, polistiren, calit, etc) cu sau faia miez de fier. Fenomenul pe care se bazeaza functionarea unei bobine este acela de autoinductie, a carei intensitate depinde de o marimea bobinei, numita inductanta (L) care se masoara in henry (H). Submultiplii henry-ului sint milihenry (mH) si microhenry (uH), intre ei existind relatia:
1 H = 1000 mH = 1 000 000 uH
1 mH = 1000 uH
Ca aspect constructiv se disting trei feluri de bobine cu aer (fara miez), cu miez din pulberi feromagnetice presate (ferite, ferocart) si cu miez din tole de tabla de ferosiliciu sau aliaje cu proprietati deosebite (permaloy).
Simbolic, pe scheme bobinele se deseneaza ca in fig, 29.
Asocierea bobinelor cu un condensator poate forma un circuit oscilant, cum sint circuitele de intrare, de acord, de FI, OL etc.
Transformatoarele formeaza o categorie de piese frecvent intilnite in radioreceptoare.
Functionarea lor are la baza fenomenul de inductie care apare intre doua bobine apropiate cu axele paralele fixate pe acelasi miez de fier. Bobina alimentata de la o sursa de curent alternativ este bobina primara, iar aceea la bornele careia se culege tensiunea indusa este bobina secundara (fig. 29, c).
Transformatoarele de radio frecventa au miez feromagnetic, fiind situate la oarecare distanta inductanta lor e redusa la citeva sute de milihenry. Transformatoarele de AF aer, din contra, au inductante mari (de ordinul citorva henry), bobinele lor fiind strins cuplate si plasate pe miezuri din tole de ferosiliciu sau permaloy.
This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Cookie settingsACCEPT
Privacy & Cookies Policy
Privacy Overview
This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may have an effect on your browsing experience.
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.