Joule Thief Made With A Ferrite Bead From An Old CFL Light Bulb

Here I make use of an old burnt out CFL light bulb for a Joule Thief light circuit. The ferrite bead/core from the CFL is at most 1/4 inch diameter and can fit in the core of my last circuit with a bit of room to spare. I used about 22 turns of fine (bi-filar=2 parallel wires) insulated wire. Comparing it to #30 gauge as shown in my last Joule Thief light circuit video, this wire seems about only half as wide (maby close to #40 gauge or so: seems slightly thicker than a human hair). If I used #30 gauge wire for this ferrite core then only 15 or so turns on it would be possible and may or may not have worked right.....it could of since the inductance would probalby be about the same as the recomended circuit. A Joule Thief circuit is basically like a "voltage step-up/increase" circuit. Voltage basically is the force that will be available to push the current around a circuit. 1.5V is not enough force or potential to push the current through a white LED light, so a Joule Thief increases that to about 3 to 6 V approximately, but can be more. I put a round ceramic magnet near the coil/transformer of the Joule Thief circuit, and the LED dimmed a bit. I guess the inductance of the coil went up leading to a higher reactance (ie. resistance) in the coil, which would diminish the available current. Some more notes for the value of R, the resistor in this circuit: 1K is the reccomended value (but could be a bit less). The circuit will work, produce some light, and diminishing ...



http://www.youtube.com/watch?v=J_tJtS0WlsI&hl=en