Joule Thief

[Pirate88179]

:)Thankyou to every one for your help !
I have onle a few LED's so i dont know how many i can light, but with one JT of mine with a small toroid out of a CFL, I wound 6 turns bifilar on it and I get around 60 VDC, but I have not been very good with producing AC-Voltage as yet, I would like to use my ferrite toroid which is about one and a half inches diameter and use the transistors that i only have - which is a 2n3904 or a bc547 or 2n2222, and if someone can show me how to wind a primary and especially a SECONDARY on the toroid, so I can get some decent
AC-voltage from it, but i need the JT to work of course.
With one of my JT that have shoen yesterday on this sight, the LED only flicked on and off when i connected the battery, but when i added a wire from one side of the secondary and ran it to the collecter or base-cant remember which one, well I got it to light brightly, but the multi-meter only still read
AC-voltage of around 0.73v, i cant seem to get a nice 100 VAC or more, can someone suggest something with the transistors that i have and also the toroid that i have ?
Thanks to everyone.
Oh, also I cant find MK1's description of a way to measure your AC !
And i can get nice high volts of DC with that 1.5 inch toroid, but i need high AC so I can light my 4watter fluoro.
thanks for the nice photos and diagrams great stuff !!!
Hope to get some replys and diagrams thanks heaps.

Others can correct me if I am not correct but I believe you are already getting ac from your JT circuits, if they are made in the "standard" JT configuration...bifilar windings, ferrite core, transistor, etc.

As Jeanna said, you can't really measure ac on a regular DMM.  It will show a number but, it will not be accurate at all.

So, my advice would be to get an 18" tube to start with and try your circuits.  If they will not light it, there are tons of circuits posted here by many that will.  Check our other sister topic (the diagrams topic) for diagrams and listings for their location within this topic.

The Fuji is the easiest way to light big tubes but plenty of folks here have some pretty simple circuits that will light them at a good light level and for a long time.

Bill

[resonanceman]

:)Thankyou to every one for your help !
I have onle a few LED's so i dont know how many i can light, but with one JT of mine with a small toroid out of a CFL, I wound 6 turns bifilar on it and I get around 60 VDC, but I have not been very good with producing AC-Voltage as yet, I would like to use my ferrite toroid which is about one and a half inches diameter and use the transistors that i only have - which is a 2n3904 or a bc547 or 2n2222, and if someone can show me how to wind a primary and especially a SECONDARY on the toroid, so I can get some decent
AC-voltage from it, but i need the JT to work of course.
With one of my JT that have shoen yesterday on this sight, the LED only flicked on and off when i connected the battery, but when i added a wire from one side of the secondary and ran it to the collecter or base-cant remember which one, well I got it to light brightly, but the multi-meter only still read
AC-voltage of around 0.73v, i cant seem to get a nice 100 VAC or more, can someone suggest something with the transistors that i have and also the toroid that i have ?
Thanks to everyone.
Oh, also I cant find MK1's description of a way to measure your AC !
And i can get nice high volts of DC with that 1.5 inch toroid, but i need high AC so I can light my 4watter fluoro.
thanks for the nice photos and diagrams great stuff !!!
Hope to get some replys and diagrams thanks heaps.

freepow

Thanks for  cropping   your   schematic 


If  you  are getting    60 V  from a 20  wrap  secondary  you  have  a good grasp  of the basics .

The  rest is   what you could call fine  tuning .
Others here are much  better at  fine tuning than I am .
Unfortunatly    it is not as simple    as   giving  you   a  number  of wraps for  each winding   ......even  knowing  that you  got   your   toroid out of  a CFL
There  are many  different manufacturers of CFLs    and many  sizes of CFLs

OK ............. so you  have  60 V  with 6 turns  bifilar .
Have you  tried 5 turns ?
If   you can get  the primary  to work  with less turns   the voltage on your secondary  will go up .
Some  toroids  can  run  with  3wraps bifilar .......  if yours will .....you will probably  have  about 120V

Once  you  have the  primarys  down to minimum wraps .....then you  add  a secondary  with more wraps .     

You need to have  a secondary  on the  toroid to tune the primarys .
Once the primarys are tuned ..... you can  pretty much  see about  how   much you need to add .
You  can then  take  off  your  original  secondary  and put on a  new secondary  lets  say  3 times  more wraps if your  voltage was  around  1/3  of where you wanted it .

At  some point  you  will  run into the  upper  power limit  of your  transitor ..... the windings   will  just not  put out the voltage they should .
Space  for  the  secondarys   on the toroid will also  become a problem




About   measuring 
All  digital  multimeters  seem to  have their  own way  of measuing   AC
Some work better than others but in  general none of them are very accurate .
The  are usually  based on  50 or 60 cycles per second ...... JTs are MUCH faster than that.

Maybe the best way is to get  a High voltage cap ......and a  high voltage bridge 
Use the bridge to  rectify the output  of your JT  .....then feed  it to the cap
Any meter  can then get  a good  reading   of the DC in the cap .

The cap  will charge  quickly   to the top of the  bulk of the  peaks .....it   will  eventually  charge  up to close  to the   voltage  of the tall skinny  spikes .....but  that takes much longer .

If  you  want a " free "   HV cap look for  an old  microwave oven that is  being  thrown out .        I found  a 1000V 10uF cap  in   a big microwave .


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`

Did   you   try  adding a tank  circuit .......like in the schematic  I posted ?
From my experience   you can pump  more power  though  a transistor  if you  have  a good sized  cap   parrallel   with the base resistor .
Speaking  of   the base resistor .....  I hope that you are using  a pot  for the base resistor  .......for tuning   JT   each  time you  change something ......run  run the  pot  to its limits slowly .......  you will  sometimes  find  resonance  ...... when that happens  you  will get more output  with less input . 


gary

[freepow]

  Hello, yes i tried your cap next to base res, thanks.
I have wound a toroid with single wire of about 50-60 turns then I wound on that a bifilar winding of 4 turns, then i connected the bifilar windings to circuit as you normally do, then with the single 50-60 turn - I connected that only to a led, it lit brightly, but its a seperate winding on same coil but on same toroid, so it must be AC
if so, I cant measure any decent voltage on my multi-meter, yet its lighting a led brightly, any comments???

[jeanna]

...

... with the single 50-60 turn - I connected that only to a led, it lit brightly, but its a seperate winding on same coil but on same toroid, so it must be AC
if so, I cant measure any decent voltage on my multi-meter, yet its lighting a led brightly, any comments???

I am surprised you still have your led!
I usually do not put more than 7 turns of a pickup (that would be the single wound one) per led. Any more than that and the led is gon-zo.

So, If you don't have enough leds, then wrap a 7 turn single pickup and use that to see. It will work. Just wrap it around with the other one. It will probably light the led and not blow it out.

Good going,

jeanna

ps
the only way you will see the ac is with a scope.
You need to put the output through a rectifier into a cap to count the voltage.
I bet you have plenty.

ps#2
The other day I decided to wrap a fluoro lighting toroid with a newer smaller toroid. I got 350v from about 330 turns. I am pretty sure if I make up a 2N3055 that it will work,
The transistor needs to give over 400 volts, more like 450 or 500v to light up a fluoro tube with voltage spikes and not amps.
but with the 2N3904 it lights a neon, (220v is all I need for that) but not a fluoro... yet.
MK1 told us he was never able to get a fluoro lit with a 2N3904 or 2N2222 either.
They are great little transistors.
I like to know the limits of things. If you keep persisting, you might just show all of us that it is possible, so I say keep going.
But don't forget to try the 2N3055 also.

j

[Pirate88179]

Exactly what Jeanna said.  The only thing I might add is that leds light well on both ac and dc and she is correct about the scope.  I toasted more leds this way in the early days then I care to remember. 

They were really, really bright...for a second or two, and then I began to smell this really awful smell and...poof.  I fried a group of 6 ultrabright leds on a wound toroid JT using a dead AA battery.  It was good news tho as I was just hoping they might light a little and ended up smoking them.

Bill