Joule Thief

[jeanna]

Jeanna i have a pot on the base thru a 47 ohm resistor with this one and i can increase or decrease the brightness of the little Florecent lamp (square one) all the way to BRIGHT to dim but after it goes out i have to crank it up to high to light again and then i have control over it . Its possible to just regulate the voltage from the battery and leave a resistor on the base without a pot there . I mean put the reostate in between the battery and jt  ? I dont have awire wound one to spare they are on all my Bedinie's .

albert

Yes, it is.
In fact it is how my golden light is wired.

There is as I mentioned a difference in what you are doing.
The rheostat which is the pot at the battery pos end is raising or lowering the maximum amount of voltage available to the transistor and not changing the pulsing part of the joule thief.

The pot we are used to adjusting is making the the frequency of the pulses but each time the voltage is on the leds are fully on.
It was what lidmotor did. I didn't get it at first, and it only works on a circuit where there is more voltage coming into the basic joule thief than is necessary.
It makes a dimmer or brighter light without changing the flicker rate. Now we don't really see the flickers, but we do, and it looks like a color difference more than a flicker difference. I do not know if I can explain it any better. It is worth looking into.

I was not able to make any use of this with a cfl of higher wattage like the 20 watt. If I raised the resistance on the rheostat the light would go off right away.
I used the trick today with a partially blown 19-led bulb because I was  wanting to lower the light while I checked it.
In my AC circuit I have used a 33 ohm resistor to severely  dim the input voltage for the sake of my eyes, so it makes a lot of sense. Radio shack has them for 4 bucks.

I hope this makes sense,

jeanna

[guruji]

Thanks Jenna for your help I am rewinding the toroid now. First I am searching for a burned wire than I should do it on another Ferrite one.
FreeInfo can you please translate those schematics that you've posted in Russian?
Thanks

[jadaro2600]

In hoping and looking forward to using my xenon flash tube.. I am wondering what the center lead is for? ..the other two are obvious.

[Gilobob]

@ guruij

Sorry for the late response. I was in bed feeling very sick and had to study for my exams. I'm a bit better now.
I tuned it so that it works best on 4 to 7 volts. So it works on a phone solar charger.
I think you drain to many amps and your 2n3055 is blown. Put a resistor at the input, and try to tune it to it sweet spot.
Mine just gets a bit warm after 10 hours.

GrtZ

[guruji]

@ guruij

Sorry for the late response. I was in bed feeling very sick and had to study for my exams. I'm a bit better now.
I tuned it so that it works best on 4 to 7 volts. So it works on a phone solar charger.
I think you drain to many amps and your 2n3055 is blown. Put a resistor at the input, and try to tune it to it sweet spot.
Mine just gets a bit warm after 10 hours.

GrtZ

Hi Gilobob it's ok I think something went wrong in the coil cause I changed the transistor and still the problem remained.
I can rewind another one no problem.
Thanks