Joule Thief 101

[dasimpson]

Hi Jenna ,You seem to to be the go to person for questions on this subject,..I was wondering about the transistors used, I just salvage parts from old pcb's,... does the heat from my soldering gun cause damage to the components?, because I've tried making a jt with several different transistors , none of the 2222 though, all different #'s, I just can't get it to work for me ,the torrid is out of a microwave,roughly the size of a quater but thicker.....I guess I need to know if you can re-use old components or do you need to buy new?...thanx .....shylo

yes you can use scrap i do for the transistors you need to know the pinouts they are not always the same

[it hertz]

Hi guys im starting to gather components for my first JT  i have downloaded the joule thief 101  PDF and it say

"The schematic shows a 1K resistor going to the base of the transistor I
recommend using a potentiometer (Pot) in place of the resistor"

What size potentiometer would i need ?
Thanx
neil

[Pirate88179]

I have used a 10k but that is because that is all I had.  It usually calls for a 1k so, as long as that is in the range...it will be fine.


Bill

[b_rads]

@all
I fully intended to do research last night but, instead I played with a basic joule thief and the Carbon/Copper/Zinc battery.  What great fun.  I could not light a 5mm LED directly from the two cells.  With a basic joule thief the two cells produced a very intense light.  I could light with as little as 10.7ma and the pot used at full on would consume slightly over 50ma.  I need to find the sweet spot where the cells are not stressed.

The DIY Copper Carbon Zinc document is here:
http://www.overunity.com/index.php?action=downloads;sa=view;down=460
The Basic Joule Thief 101 document is here:
http://www.overunity.com/index.php?action=downloads;sa=view;down=441

Have fun!
Brad S.

[Pirate88179]

Brad:

Nice work.  Be careful that you are not sending too much voltage into those leds as you can fry them easily with a JT when running only 2 of them.  Trust me on this...ha ha.  It will be good to see how long your cells perform with this load.  You might try adding a supercap of 5 to 10 farads in parallel with your cells, that has always helped my longevity.

Bill