I left the Joule Thief running for 3 days and nights after starting it up on a battery with 0.65 volts. It kept the LED running until the battery hit 0.32 volts.
That is quite impressive for a circuit which lights a 3.2 volt LED on a battery that was previously considered dead.
I had been checking in on the device through that entire time to see how long it would run.
After 3 entire days the LED finally went out.
I put another dead battery into the battery holder and left the circuit running.
This is a sort of free LED night light using batteries that I had considered dead and useless.
Remember to check out the article and see how to make a Joule Thief for yourself: http://www.thedoityourselfworld.com/articles/article.php?id=11461
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