Joule Thief

[jeanna]

...how come my digital mm only says under 1 volt AC,
...  I've have seen some pictures of youtube JT's that show a normal digital mm measuring 700+ AC,

This reply is on the new installation of ubuntu.. I may fumble a bit.

I cannot say what those youtube videos are showing, but not one of us here has ever gotten the joule thief ac to show up correctly on a dmm.

The other thing is you will probably need more turns than 60.
I know xee2 got a fluoro tube to light with 80, but I think he holds the record for the least number of turns.
I am not aware of anyone who has lit a fluorotube using the 2N2222 or 2N3904. Xee2 never uses that kind of transistor at all.

You can do this.
We who wanted to have all done it.
but you may need to modify what you are trying a bit... Maybe not.

yet i cant even know how much i'm getting of this winding that i mentioned, how much AC do you think i'm puttint out???

yup, that is the hard part.
I tried to find a scale so someone could compare but I was not able to, but I am sure if your dmm says less than 1 volt that you have less than 100volts.
You will need NOT 240volts, but 500v.
This is different. You need about twice what the "normal" amount would be.

So, wind up a lot more.
Also, if you can find some leds (ebay has chinese ones for under $10/100 leds directly from china). You can put 6 to 8 of them in series with your toroid and get a light that is very bright.

It is not the same challenge, but the light from 6-8 leds could actually be MORE than from the 4 watt fluoro.

It is all fun too.

jeanna

[dankie]

Hi ,

If you have a inexautible supply of electrons @ 3 volts DC , you should make an cmos inverter with a VERY BIG WINDING 50:1 transformer .

If that doesnt work , there is not much hope for jules thief , the voltage is too much a limiting factor ...

[freepow]

Can you light up an AC-fluoro on very high DC-joule thief that is bifilar wound???
Can you get 300+ volts in DC from one bifilar wound toroid???
And can someone draw me a simple joule thief circuit that works, that put out at least 50 volts AC...please, thanks.

[resonanceman]

:)Thanks resonanceman, but how come my digital mm only says under 1 volt AC, and i still cant light my 240VAC 4 watt fluoro with that circuit and toroid winding,  I've have seen some pictures of youtube JT's that show a normal digital mm measuring 700+ AC, yet i cant even know how much i'm getting of this winding that i mentioned, how much AC do you think i'm puttint out???

Freepow

It is impossible  to say  how much your JT is putting out .
With a JT  the way to tell  is according to what you can  do with it .

I  have some  LED arrays that  I took out LED floodlights .
The normal out of the box operating  voltage for my 60 LED array is  84V but  I  have  driven  it   with  different JTs  with  an  indicated   voltage ( same meter  as I measured  the  84V  .....same  location )  of 18 V  up to 250V
I think  with the 18V I was lighting  the LEDs  with  the spikes .
I  have no idea why  the 250V  did not  burn  the array out instantly .
I did  burn one  array out and  damaged  a meter and  fried  a 3055 ......all in a split second .     I was  making  a JT using  a MOT ( microwave oven transformer )

How  did you  arrive at 4 turns bifilar ?
Did  you start  with more than 4?

4 should  work unless you have a high permeability toroid .
I always suggest starting  with more wraps  and taking some  off once you get it  going .
It will not  fail to work because of to many wraps ......it WILL fail to work if there are to few wraps for that particular  toroid  .

According to your picture  you have  your  primarys  on top of your  secondary.
I have played  with this some ........ it can work but  in general  you need more wraps  to make it work .
for now .......forget about your  blue bifilar .
The  winding  I  have drawn should  also be  bifilar .
wrap it in the  open  space  between the ends of your secondary .
Keep  the windings  close to each other .
Notice  I drew  it  with the  wraps touching on the inside of the  toroid .
I twist  the ends of the  primarys together so that  the outside of the windings are touching also .
4 wraps  may work .   I would  start  with 5 or  6  then hopefully  get it down to  4......maybe 3

[freepow]

Thanks, but with my winding, all that happens is a bright led light ok on the secondary, but if i connect the led to the bifilar and emitter, it light very bright,  it seems that the secondary is not out putting much AC at all, i'm not having much luck with any high AC no matter what winding i am doing, whats going wrong ?
I have tied that blue bifilar winding with 20 wraps originally-got around 113v i think, then decreased it each time and the volts also went down, so i ended up down to 4 turns,  but why is the secondary of mine with 60 turns only lighting led just OK-and is not burning it out either???
I need some high AC, but cant seem to get any!