Joule Thief

[jeanna]

Jeanna may i ask if your new way of winding coils works good even on small toroids. I am asking because I just can't seem to be able to go over 40 volts. even tho I have tried like 30 times with various toroids and sizes

Dennis

Hi Dennis,
Several things come to mind.
1- the transistor makes a big difference.
I get double or triple the volts when I use the TIP31 or 3055 over what I get when I use the 2N3904, or 2222.
This comes at an cost of higher amps draw.The transistor takes battery power, and that is all there is to it. The little ones take less and give back less, so match your transistor to the application.
2- the tuning of the primary in respect to the toroid.
Did you tune it? and how?
This means you wind the primary windings and prove the jt works, then remove the led from the C-E junction and wind some, maybe 5 to 10 turns around the toroid and sand the ends of the mag wire.

Now, if you are using a dmm, you will have 10-100 times what the dmm shows, so watch out.

Test the small secondary by holding one led and lightly touching the other lead to a leg. If there is no light then reverse the wires. (and make a mental note or you will make yourself nuts.)

OK, so you have the polarity right, now take the base resistor which should be a 1k pot, and slowly turn the pot til you get a bright spot.
Now, you can measure that resistance with the ohms meter on your dmm.
Many times I find 2 bright spots. I ALWAYS use the one that is a higher ohm value for 2 reasons.
lower amps draw
no threat of overheating the transistor

Now, you add and subtract a few of those primary turns.
The numbers here relate to the permeability of the toroid and you just have to slog through this.
One by one take out base turns til the light stops brightening
Then one by one remove collector turns with the same thing in mind.
Usually the jtc works MUCH better with fewer turns on the base.

You can try for the best light by turning the pot, but I find that I don't need to do that until I get close, but MK1 and Gary like to sweep the pot each time.

OK
Now for the secondary,
with the primary at it's best-so-far numbers change the turns on the secondary until the led is too bright.
Now, figure that number of turns per led and wind away.

I have used that new method since I discovered it for all but my last one.
I find IF the toroid is a good one, and I guess you have tried many? that the problem could be that you have put on too many turns and choked it.
I rescued one with that problem by unwinding about 30 turns then since the volts were back up, I just rewound the turns with the scramble method, just all in one row, but not precise and away from the ends.
I think you can choke it by getting too close to the primary.
I used some cotton string and wound 3 turns around the outside ends of the primary and it helped a lot.

Please let me know how this works.
Anybody else with ideas, please jump in to help.

jeanna

[Pardon]

Hi Dennis,
Several things come to mind.
1- the transistor makes a big difference.
I get double or triple the volts when I use the TIP31 or 3055 over what I get when I use the 2N3904, or 2222.

2- the A of the primary in respect to the toroid.
Did you tune it? and how?

Now for the secondary,
with the primary at it's best-so-far numbers change the turns on the secondary until the led is too bright.
Now, figure that number of turns per led and wind away.

I think you can choke it by getting too close to the primary.
I used some A and wound 3 turns around the outside ends of the primary and it helped a lot.

Please let me know how this works.
Anybody else with ideas, please jump in to help.

jeanna

thanks for the help. i will switch to a tip31 or 3055. i used mks tuning instructions. but i didn't readjust the pot after making coil changes. but i think you gave me the answer. I now believe i am choking it. i will try the string trick. I must have missed the small secondary 1 led windings step.

just tonight i wound a tor-53 with a 6t base and 6t collector. it's so bright i can hardly look at it. it pulls 10.2 ma with a 1k base resistor using a 3904 trans.

again thanks for the help

Dennis

[Pardon]

Hi Dennis,
Several things come to mind.
1- the transistor makes a big difference.
I get double or triple the volts when I use the TIP31 or 3055 over what I get when I use the 2N3904, or 2222.
This comes at an cost of higher amps draw.The transistor takes battery power, and that is all there is to it. The little ones take less and give back less, so match your transistor to the application.
2- the tuning of the primary in respect to the toroid.
Did you tune it? and how?
This means you wind the primary windings and prove the jt works, then remove the led from the C-E junction and wind some, maybe 5 to 10 turns around the toroid and sand the ends of the mag wire.

Now, if you are using a dmm, you will have 10-100 times what the dmm shows, so watch out.

Test the small secondary by holding one led and lightly touching the other lead to a leg. If there is no light then reverse the wires. (and make a mental note or you will make yourself nuts.)

OK, so you have the polarity right, now take the base resistor which should be a 1k pot, and slowly turn the pot til you get a bright spot.
Now, you can measure that resistance with the ohms meter on your dmm.
Many times I find 2 bright spots. I ALWAYS use the one that is a higher ohm value for 2 reasons.
lower amps draw
no threat of overheating the transistor

Now, you add and subtract a few of those primary turns.
The numbers here relate to the permeability of the toroid and you just have to slog through this.
One by one take out base turns til the light stops brightening
Then one by one remove collector turns with the same thing in mind.
Usually the jtc works MUCH better with fewer turns on the base.

You can try for the best light by turning the pot, but I find that I don't need to do that until I get close, but MK1 and Gary like to sweep the pot each time.

OK
Now for the secondary,
with the primary at it's best-so-far numbers change the turns on the secondary until the led is too bright.
Now, figure that number of turns per led and wind away.

I have used that new method since I discovered it for all but my last one.
I find IF the toroid is a good one, and I guess you have tried many? that the problem could be that you have put on too many turns and choked it.
I rescued one with that problem by unwinding about 30 turns then since the volts were back up, I just rewound the turns with the scramble method, just all in one row, but not precise and away from the ends.
I think you can choke it by getting too close to the primary.
I used some A and wound 3 turns around the outside ends of the primary and it helped a lot.

Please let me know how this works.
Anybody else with ideas, please jump in to help.

jeanna

[Pirate88179]

                   ***IST's posts removed by the Moderator.***

They will continue to be removed unless they are on topic.

Bill                

[jeanna]

The "World Light"
Hoping teenagers around the world will be able to put together some lights from used cfl bulbs to make lights for the people in the village.
My contribution for the world to be a brighter place!!

http://www.youtube.com/user/jeannacav#p/a/u/0/GAMnnyD7VQc

jeanna