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joule thief won't work for me, can't figure out the problem Answered



i made joule thief as shown everywhere in instructables, I tried few different transistors, and toroids, I had like 100 tries, and can't get it to work?

and: can I use transistors-in the middle of the last picture?

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xtony666
xtony666

11 years ago

i found out what was the problem-I bought 1k, and 2n3904,bc337,tip3055 transistors, and it works with all of them, toroid was ok

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NachoMahma
NachoMahma

11 years ago

.  Can you post some clear, close-up pictures of what you have put together?

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xtony666
xtony666

Answer 11 years ago

uploaded, I'll upload more if necessary

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NachoMahma
NachoMahma

Answer 11 years ago

.  All the joule thief schematics I found called for a resistor (often 1K) on the "B" coil. I don't see a resistor on any coil leads.

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xtony666
xtony666

Answer 11 years ago

sry for bad angle of the pic, it's on the middle leg of the transistor, and B coil, I don't know if it's 1K, anyway, can I use transistor on the last picture?
if still won't work, I'll buy pieces that are exactly needed and try, should work

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NachoMahma
NachoMahma

Answer 11 years ago

Search Google for "resistor color code".
.  I can't read the numbers on the component in the center of the pic, so I can't look it up, but I'm betting that it is a voltage regulator, not a transistor.
.
.  Did you try steveastrouk's suggestion (reverse one pair of windings)?

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xtony666
xtony666

Answer 11 years ago

i didn't, :S what do you mean reverse it?, i held 2 wires together and turned them around toroid bead

and does it matter which transistor I use, i used ones that look exactly the same as in other instructables, but dont know if they are NPN? - seems to me like it would be best to buy 2N3904 transistor like most people have


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NachoMahma
NachoMahma

Answer 11 years ago

.  Let's call them coil A and B and the ends are 1 and 2. If the current connection is A1/B1 and A2/B2, then swap the wires on one coil so that you have A1/B2 and A2/B1.
.
.  It has to be the proper polarity and you can't tell by looking at it. If the schematic calls for an NPN, it has to be an NPN. Do a search for the transistor number - 2Nxxx - and you can find out if it's NPN or PNP. I'd use whatever transistor the schematic calls for.

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xtony666
xtony666

Answer 11 years ago

ok thank you very much for your help, I'll try reversing, and get transistor I need
so I'm sure it will work
and then I'm going to make instructable (not for joule) but something with it(if that will work) :)

tnx

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NachoMahma
NachoMahma

Answer 11 years ago

.  I wouldn't do both at the same time. Replace the transistor with the proper one; if it still doesn't work, then swap the wires.

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steveastrouk
steveastrouk

11 years ago

Try reversing one pair of windings