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joule thief: can i use a cellphone battery charger to power a joule thief? output 5v~ 400-600mah.

What resistor should i use? a 1k resistor,220ohm or a variable resistor/potentiometer B50K is ok? 

masters help pls.. im noob

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Why ? That much current isn't suited to a JT circuit.
reopoop (author)  steveastrouk3 years ago
Sir i have C1815 and A1510Y transistor.. is it ok to use this kind of NPN transistor? and what is the mininum turns to make a led brighter?
What are you actually trying to do ?
reopoop (author)  steveastrouk3 years ago
just a regular joule thief sir.. it just i got my transistor from an old audio/video converter.. and also the resistor are from there.. i just want to know if this C1815 transistor is ok or will suit on this project.
You don't need 500mA to power an LED ! What are you trying to do ?
reopoop (author)  steveastrouk3 years ago
actually i already built just now my 1st joule thief using this parts i got in old audio/video converter
C1815 transistot,,
Red,orange,black,gold resistor
LED.. color white LED but Blue when it lights up.
FerriteToriod w/ 7turns
And a rechargeable battery Panasonic 1.2v. up to 2600maH(it is written on the battery)

Result = Failed..

it only lit if i use 2pcs. battery..that Panasonic battery.. . and a very low light produce actually
iceng3 years ago
Joule thiefs are for sucking a battery dry and in some cases doing something useful.
reopoop (author)  iceng3 years ago
tnx sir
And if you JT a lithium cell, it may well lock out permanently
If you already have a good 5V source why do you need a joule thief? The whole idea behind using a joule thief is to get that extra bit of juice you need from an old batter to power an LED.
reopoop (author)  mpilchfamily3 years ago
tnx for the info