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Joule Thief Artbots

A popular circuit for electronic hobbyists called a "Joule Thief" has been making the rounds on the Internet.


When your batteries go dead, there is still energy or "joules" still left in that battery. Instead of simply tossing
 it out to get recycled, why not squeeze out the remaning joules of life to do something useful.

With the Joule Thief circuit you can light a white led till the battery is down to .2 volts. Use it for a night light, it will run for days.
 Then, when it is good and dead, give it to the trash collector to get recycled.

A simple enough circuit that can be modified to do different things. You can take apart a CFL energy saving bulb to get the ferrite core.
Q1 can be subsituted with a Supertex TN0702N3-G mosfet from Mouser.

Joule Thief Artbots I have made

Blink with Temperature

Sound Activated


Dark side of the Force

Big D

Heavy Ferrite



My blog about My JTs

My Instructable on using a JT to charge another battery

Links to others who have built Joule Thiefs

Watson's eblog
Evil Mad Scientist Laboratories

The Family of Joule Thiefs

To the rest of Bill's Artbots