Toroids are often used because the ring shape is very effective at storing electromagnetic energy, but you don't actually need a toroid to make a Joule Thief. A simple coil with two windings around a central core will work just fine.

Dec 14, 2009 · Could the oscillating magnetic field actually cause the ferrite core to flex or could it be a vibration of the windings? I suspect it is the core. Getting the Joule Thief circuit to work does not require an oscilloscope but, a bit of experimentation may be …

Salvaging ferrite cores. The most uncommon element in this circuit is the ferrite toroid (also called a ferrite bead or core). Unlike NPN transistors, 1Kohm resistors, or LEDs, these aren't usually part of a beginner's or hobbyist's kit. So, where do you get them – and what kind do you need?

A joule thief is a minimalist self-oscillating voltage booster that is small, low-cost, and easy to build, typically used for driving small loads, such as driving an LED using a 1.5 volt battery.

Mar 2, 2015 · The principle of it's operation based on the saturation of the ferrite, and then the discharge of the stored energy through the LED - the number of turns (within a wide range) would determine only the operating frequency.

Dec 8, 2017 · I read about someone who did it without an ferrite toroid and used an iron core. Make a Joule Thief Coil Without a Ferrite Toroid: 5 Steps (with Pictures)

The joule thief circuit can be made in different ways, and involves a ferrite core with two windings and four terminations. The base current limiting resistor is 1k ohm. A low power NPN or PNP transistor is also used.

A “Joule Thief” is a simple voltage booster circuit. It can increase the voltage of a power source by changing the constant low voltage signal into a series of rapid pulses at a higher voltage.

Ferrite cores, often specified in the making of the JT, depend almost entirely on the material used to make it, and it is impossible to guess its performance at a glance. For example, the first coil on the left is half the size of the larger one to its right, yet it has an impedence (magnetic reactance) 8-times greater , even with the same ...

Apr 10, 2013 · 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.)