Created by
Created September 04, 2012
Last modified September 04, 2012
Tags joule-thief   timed-light   timer  


A simple single coil Joule Thief with a timer function.


A single coil Joule Thief light with a built-in timer.

Pressing SW1 will start the timing cycle which is approximately 40 seconds x Cx (uF). D1 and C2 steal some of the output to improve efficiency and to act as a capacitance multiplier to keep Cx small. With the values shown the delay is 3.5 minutes.

Brightness can be further improved by substituting a BC337 and BC327 for the NPN and PNP transistors.


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