What is the joule thief circuit?
The Joule Thief Circuit is a voltage booster circuit which converts a constant low voltage input into a periodic output of a higher voltage. This circuit can be most often seen lighting an LED with an almost dead AA battery. The peaks in voltage occur rapidly, causing the LED to flash at a very fast rate.
What is the purpose of a joule thief?
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. This circuit is also known by other names such as blocking oscillator, joule ringer, vampire torch.
How do you make a joule thief without a toroid?
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.
What is meant by toroid?
1 : a surface generated by a closed plane curve rotated about a line that lies in the same plane as the curve but does not intersect it. 2 : a body whose surface has the form of a toroid.
What is a ferrite toroid?
A ferrite toroid is a product that is able to provide high magnetic efficiency, and this is due to the fact that no air can get through the cross-sectional area. A ferrite toroid has permeability the ranges from 5,000 J material to 10,000 W materials.
How efficient is a joule thief?
So designed the Joule thief was able to produce 34 V voltage measured on the collector node of the NPN transistor (2N2222) without any load, when supplied by 1.2V AAA battery (filterd with 2.2uF capacitor).
What is a toroid bead?
They are passive electronic components, consisting of a circular ring or donut shaped magnetic core of ferromagnetic material such as laminated iron, iron powder, or ferrite, around which wire is wound.
What is toroid formula?
The magnetic field of a current-carrying toroid is independent of the radius. This is because the magnetic field of the toroid is given as B = μonI where n is the number of turns, I is the electric current, and μo is the permeability.
Where is toroid used?
Toroidal inductors and transformers are used in a wide range of electronic circuits: power supplies, inverters, and amplifiers, which in turn are used in the vast majority of electrical equipment: TVs, radios, computers, and audio systems.
What is the primary winding of a Joule Thief?
I’ll try to avoid any magnetic theory or heavy math. A Joule Thief coil has two windings, only one of which is needed to do the voltage boosting. This winding is commonly called the primary mainly because that is what the input winding is called in a transformer.
Is the joule thief circuit made over a torroid core?
As can be seen in the shown joule thief circuits, the coil is ideally made over a torroid core. The details of the coil could be found in the following article. The coil structure is exactly similar and compatible with the circuits discussed on this page.
What kind of wire does a Joule Thief use?
The coil consists of a standard ferrite toroid core with two windings of 20 turns each using 0.15 mm (0.006 inch) diameter wire (38 swg) (34-35 AWG ). The circuit can utilize an input voltage down to about 0.35 V and can run for weeks using a 1.5 V LR6/AA.
How does a Joule Thief boost the voltage?
Basic Single Winding Inductor Let’s use a singe winding coil, also called a choke or inductor as an example of how a Joule thief boosts the voltage. We have a circuit that is a coil and a LED in series, with one lead of the coil connected to the positive of the 1.5V battery and the cathode lead (flat spot) of the LED connected to the negative.
