Small Joule Thief

by bananagirl

12K4712

Intro: Small Joule Thief

I saw a tiny joule thief here: http://www.bigclive.com/joule.htm.  I wanted to replicate the size, but leave the application open for use in different projects.  By following this excellent instructable: https://www.instructables.com/id/Make-a-Joule-Thief/ I was able to fit my circuit inside a 5x5 square of perfboard. It happily powers 3 leds in parallel. 

8 Comments

Radionuclei95 11 years ago

i just made one in a 3x4 piece of perfboard

bananagirl 11 years ago

That looks awesome!! Makes me want to go even smaller...Where is the resistor though? Underneath the board disqualifies you from competition(!)

reopoop 10 years ago

guys i want to makeone of this but i only have C1815,A1510Y transistor.. and dont know the resistor to use because i dont know the color to choose..

absolute zero 11 years ago

This is very neat, very clean looking as well!
I was wondering if you remembered where you got your ferrite bead from. I can't seem to find any. Also, I noticed you have only 5 wraps where most other thiefs use upwards of 20, does that effect the performance at all?

bananagirl 11 years ago

Hi! Thank you! I found the tiny ferrite bead inside a Philips "Genie" 11w CFL bulb. The instructable I followed recommended 6-11 turns on the bead, with 11 being the maximum advised. I used the smallest wire available to me and just squeezed 5 turns. It has been running 3 UV leds in parallel for a few nights now from an otherwise dead battery. Everything seems to work OK, but I'm not really sure how to test performance to be honest!

absolute zero 11 years ago

Okay, thank you! The only ferrite I have been able to find is much too big, I will continue to scavenge :)