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ins1337

Control de tensiune

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Salut, imi pute-ti da si mie o schema pentru urmatorul circuit.....Vreau sa alimentez un bec de 12v 5w si sa imi cresc sau sa ii reduc tensiunea cu un potentiometru chestia e ca dac apune pe direct se duce potentiometru si imi trebuie o schema de variatie in asa fel incat sa nu stric piesa. Nu vreau foarte complicata. Multumesc!

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Potentiometrul singur nu rezista la curentul becului (zecimi de Amper) decat daca este mare si bobinat (facut din sarma destul de groasa) ca sa radieze in aer caldura degajata (cativa Watt).

 

Poti incerca si ceva de genul asta:

http://s1136.photobucket.com/user/ticu2 ... sort=3&o=0

Tranzistorul trebuie montat pe radiator termic suficient de mare.

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Mersi de schema, cel de 50 de k este potentiometru presupun, dar de ce vine dupa el in serie urmatoarea de 1k?

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Rezistenta de 1K preintampina legarea pinului 7 direct la plusul sursei (suprasolicitarea iesirii lui 555).

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Prima schema functioneaza in comutatie . deci tranzistorul de comanda v-a disipa putin .poti pune si alt tip in capsula to220 dar cu beta cit mai mare . trebuie sa asiguri un curent de baza suficient pt. saturatia tr. verifica daca iesirea 555 are suficient curent pt. asta.

cea de a doua e liniara si are nevoie de un radiator mai mare cum arata si schema.

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555 livrează 200mA fără probleme.

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