How a Joule Thief Works
Step-by-step run through of how a Joule Thief circuit works. Includes how all the parts, the 1.5 volt AA battery, the resistor, the transistor and the ferrite core with its two coils of wire work together to build up energy in a magnetic field which then collapses to produce enough voltage and current to light an LED (Light Emitting Diode.) This includes explanations of the feedback that rapidly opens the transistor between base and emitter to open up the emitter to collector too. And also the feedback that slams the transistor shut again.
See also this video on How to Make a Joule Thief (called Make a Joule Thief for Zombie Batteries):
For how to make a joule thief power a compact fluorescent light (CFL) watch "How to Make Joule Thief Light a CFL – Jeanna's Light":
For all sorts of measurements and demonstrations of my joule thief powering a CFL watch "Fun with Joule Thief Powering a CFL":
And also this webpage about Joule Thiefs:
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