Thread: Big Joule Theif
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Old 11-23-2010, 12:35 PM
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Tectalabyss Tectalabyss is offline
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Run time's

Originally Posted by Vaporizer View Post
Hi Tectalabyss and thanks for the welcome. 2 weeks? Are you talking abt the LED thats across the E-C junction? On the feedback, are you trying to extend the run time using it? I've read so much I need to go back through my folders I saved and reread a lot. If I remember right, most say you can't refeed the voltage back into the source battery. It just doesn't work. It needs to feed a separate charging battery. I know the Bedini circuit is this way so I may be confusing them.

I have gotten hung up on using the disposable camera circuits I had , which are basically JT's, to run a 9w CFL. A 1.25v AA I can get abt 10hrs from it at maybe 1/4 brightness. I thought it was 1/2 bright but now I dont think so. I upped it to 3v and saw very little diff other than it blew the transistor...
The coil is tiny. It will set inside the center of a goldmine toroid. I changed the transistor to a TIP series and back to 2.5v. It lit much brighter but was getting pretty warm. I looked and the Base resistor was 470ohm. I removed it and put a 1K variable in it. Interesting results. There are 2 settings that give the brightest light. One the transistor stays cool to touch and the other the transistor is hot. On the "cool" setting its still 2x as bright with 2.5v(compared to a single AA) and I'm getting a min of 10hrs on the 9w CFL using 2 AA 1.25v rechargeables. I tried winding a goildmine toroid with a 10:1 ratio and adding it to "kick" the camera coil up. It just doesnt work. I tried isolating it with diodes, caps...nada. Its like the last coil wants to much. If I would wind it with thinner wire so it had more resistance it may work and a smaller core too. The camera output coil is abt 390 ohms.

I have a pic saved I need to find where someone series 2 of them I think. Might try that, or mount it as is and move on. I have 2 3" new toroids I ordered from ebay and 10 2 3/8" that still haven't arrived.

Nick is right. Unless you gut the CFL it will not work. Mine had what looked like a neon in it with a cap.

pentiger, nice vid and that's a lot of light. I cant say if that is normal or not as I'm not quite to that next step yet. You might try the variable base resistor to see if you are using to much to "trip" the transistor. I did read that most use 350-450 turn "pickup" windings. More than that , little increase was noticed.
Hello Vaporizer and all.
That's with a small secondary running to a feedback circuit running 10 5mm white leds in parallel across the e c junction by the second week they were getting dim so I didn't post anything about it. Tec

Last edited by Tectalabyss; 11-23-2010 at 01:19 PM.
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