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Topic: a silly Joule Thief :o) (Read 6924 times) previous topic - next topic

a silly Joule Thief :o)

here my first try at a joule thief :-)

it seems pretty good,  i started with and alkaline at 0.9V and drained it during the last week, to 0.48V ...
this seems to be the best it can do ...


i used circuit B from
http://http://talkingelectronics.com/projects/LEDTorchCircuits/LEDTorchCircuits-P1.html
with modification on the toroid, mine has a lot less winding than the original circuit ...

i really need a scope to see what is happening and to try few tweaks.

is there a way to drain more juice from those old batteries ?. 
i guess some kind of multistage with some caps (miller engine !?)
of course it will not light a led but it might be good to pulse it from time to time...

any suggestion ?  :o)

Re: a silly Joule Thief :o)

Reply #1
.48 is pretty good :) Nicely done!
Got a question? Please ask in the forum for the fastest answers.

Re: a silly Joule Thief :o)

Reply #2
Nice, I'd also like to do some short research on the topic.
I'd suggest you use Germanium or hybrid transistors which have less than 0.2V saturation voltage. this way you can generate the oscillation required for voltage boosting down to 0.2V.
Still learning
-Arup

Re: a silly Joule Thief :o)

Reply #3
[quote author="arupbsk"]Nice, I'd also like to do some short research on the topic.
I'd suggest you use Germanium or hybrid transistors which have less than 0.2V saturation voltage. this way you can generate the oscillation required for voltage boosting down to 0.2V.[/quote]

i will like to play a bit more with the concept, but im still to noob  :o(  ,
i only know few BJT (with their bad junction drop)  and nothing about MOSFET or other newer types :o(
other big prob, i don't have a scope ! ...  but this ... could be fixing itself during summer probably  :o)

if you have any suggestion or want to share your finding, i will be happy to read them :o)


Let all go for the freedom of electrons !


Re: a silly Joule Thief :o)

Reply #5
Someone suggested using Germanium transistors, but they're difficult to obtain.  The JFET TN0702 will work down to less than 0.1VDC in a Joule Thief, however that low voltage doesn't give you much light from the LED.  It will drain the battery eventually, though.  The schematic in my blog  rustybolt daht info slash wordpress slash /?p=132 shows how I did it.  Recently I found a schematic on Youtube of a JT that uses a regular transistor (BJT) that can start at 0.4VDC, and run at as low as 0.24V depending on the transistor.  The transistor I used was a BC550C, and the secret is in the coil windings ratio.  Here's my blog on it. rustybolt daht info slash wordpress slash ?p=1136

Re: a silly Joule Thief :o)

Reply #6
It wouldn't allow me to put the URL, so I had to mutilate it.  There are no spaces before and after the slashes, etc. Sorry.

Re: a silly Joule Thief :o)

Reply #7
The Joule Thief I made was similar to the one I saw on a Youtube video.  At first I didn't believe that you could make a regular silicon transistor JT work at less than a half volt.  Then I built it like the one  in the video and it made a believer out of me.  You can get the details by going to rustybolt dot info, click on the link to my blog, and in the browser's address line, change the part after the question mark to p=1136.