Joule Thief

[kooler]

ok
once i get my camera charged i will post some pics
of it lighting 4 10mm leds with a triple a batt

oh i told you guys wrong . i torn it down to count the turns
it has 21 turns and three layers of 7 in a row

and it is a toroid shape of 2.5 inches tall and 4-5 inches in diameter

hope this helps to picture it ,till i get a picture of it

[xee2]

# kooler

hope this helps to picture it ,till i get a picture of it

Sounds interesting. I am looking forward to seeing your photos.

[dllabarre]

I put an AA battery that was 1.2 volts on my JT 3 weeks ago.  It's now down to 288mV and the 3 red LEDs are still lit (dim of course).

DonL

[dllabarre]

This may help you to visualize.
http://www.allaboutcircuits.com/vol_2/chpt_9/5.html

Scroll down the page of the above link to the example of boosting.
This is what I believe is happening with the Joule Thief.

DonL

[xee2]

@ dllabarre

I put an AA battery that was 1.2 volts on my JT 3 weeks ago.  It's now down to 288mV and the 3 red LEDs are still lit (dim of course).

DonL

Thanks for the info and diagram. That should not be possible since the transistor needs about 0.5 volts between B and E to work. But you are doing it. That is very interesting. You are getting a silicon transistor to work off of almost as low a voltage as a germanium. Will it start again if it is stopped?