145Views4Replies

Author Options:

3w led with two D cells. Answered

The led is 3,8V drop 800mah, and the bateries are only 2,4-3v, there is any simple circuit to make it work properly? Maybe a joule thief, but i don't know if i can pull 800mah from it. Any sugestions? thanks.?

4 Replies

user
frollard (author)2012-09-02

3.8v@800mA is a stretch for 2 d-cell batteries. Up it to 3 batteries, because any boost converter you find is going to have a problem with 3 watts from 3 volts.

Select as Best AnswerUndo Best Answer

user
notingkool (author)frollard2012-09-02

there are already boost that draw 1w from a single AA cell. why not 3w from two D cells?

Select as Best AnswerUndo Best Answer

user
frollard (author)notingkool2012-09-02

*that said

this is the closest I can find in a flashlight driver variant. Only puts out 700-800mA on 1.5-3v input.

http://www.dealextreme.com/p/700-800ma-3-mode-regulated-led-driver-circuit-board-for-diy-flashlight-3v-pair-128086?item=18

Select as Best AnswerUndo Best Answer

user
frollard (author)notingkool2012-09-02

The 1AA 1W boosts are usually not actually putting out the full watt -- I have a 1w led flashlight that runs on a AA or lithium equivalent size - and the 3.7v to 4v boost is doable, the AA mode is significantly dimmer.

Select as Best AnswerUndo Best Answer