Joule Thief 101

[innovation_station]

sounds great!

i have seen cap is not needed on input ..

some will argue this it is because they want the thing to run on 1 ma for months...

no concern for my designs

i put the tesla mini .. first .. as it is the best one i have made   

infact not seen another yet!  if you had 2 outputs like that coil then recitifer 1 from each side ..  intresting results as it is mk2 winding config..  there out of phase of 1 another cold ac ?

w

here is a picture of yet another way it can be done  and if you tune the coils to 7.xx hz  might be intresting or perhaps a magnet

[resonanceman]

it was super fine im thinking 34ga

more pictures comeing ..

i have lots.. 

i have been unable to find the solder spool ones!



ill have to dig out a box full of em  then ill snap a few pics.

w

IST

Great pictures   

I look forward to  seeing more .


I have a request .
This  thead  is  for learning.
The  pictures  are great  but  do you  think  you could  add a few words about  these JTs.
I DO NOT want complete specs .......  just a few words .
Maybe  what is unique about it .........or  why it was hard to make .
Ir why it was a first  for you. .......
Your pictures  can  be  turned into a VERY  valuable  teaching tool with  just a few words of description about each coil



I am also  courious  about some of them,
If you don;t   choose to say anything on your own   I might  ask  you  questions about them .......I imagin I could  finish posting  all my questions within a week  or so .




gary

[jeanna]

What's the purpose of the capacitor in parallel with the resistor?

Hi Broli,
This is not absolutely necessary.
It acts as a sort of 'repeater' and reduces the amps draw.
It seems that with it there( at the right size which is critical), the repeats take the place of more juice coming in from the battery.
This allows you to set the base resistor at 10k ohm rather than 1k ohms to get the same switching.

I only resort to using this with a fluoro tube. And, then it was the thing that got mine to start.
But, I believe I had too few turns on mine and it would not have needed it if I had more turns.

good question.
thank you,

jeanna

[jeanna]

I just found a good picturs from early last winter.
This is 3 turns on a secondary.
These lights are very bright and I suspect they may all be in parallel, but the way they are lined up makes me think they are series as well... bright output.
This is a cam from the computer and not from the digital camera which adjusts for light.

This is to give a good example of how great it is to use the secondaryand NOT the regular C-E junction, for the light, if anyone is still in doubt.

egads it even still has the regular joule thief light in there too! this is a very old pic!!
jeanna

[broli]

http://www.overunity.com/index.php?topic=8341.msg210330#msg210330

I have been looking at those and I believe I understand the principle on all but the second one was tricky. It took me a bit to understand what was happening or so I believe.

So current flows to 100nF cap, this current causes induction in lower JT winding. Now current flows into base and opens transistor. This makes a less resistive path to battery so even more current is now allowed through upper winding, again this causes induction in lower JT winding and opening the transistor even more, while that is happening the 0.77nF cap quickly charges and stops current flow. Then the transistor abruptly shuts off and our discharge happens.

If this is correct, then whoever came up with that circuit thought it through pretty good, it's beyond me how you can find the exact values to get it working.