The Barkhausen Effect experiment
created on January 30, 2005 - JLN Labs - Last update March 9, 2005
Toutes les informations et schémas sont publiés gratuitement ( freeware ) et sont destinés à un usage personnel et non commercial
All informations and diagrams are published freely (freeware) and are intended for a private use and a non commercial use.
"Heinrich Barkhausen, a German physicist, discovered in 1919 that a slow, smooth increase of a magnetic field applied to a piece of ferromagnetic material, such as iron, causes it to become magnetized, not continuously but in minute steps. The sudden, discontinuous jumps in magnetization may be detected by a coil of wire wound on the ferromagnetic material; the sudden transitions in the magnetic field of the material produce pulses of current in the coil that, when amplified, produce a series of clicks in a loudspeaker. These jumps are interpreted as discrete changes in the size or rotation of ferromagnetic domains. Some microscopic clusters of similarly oriented magnetic atoms aligned with the external magnetizing field increase in size by a sudden aggregation of neighboring atomic magnets; and, especially as the magnetizing field becomes relatively strong, other whole domains suddenly turn into the direction of the external field." from the Enclyclopedia Britannica.
You will find below, a very simple experiment that you can done by yourself, you need only :
A phone amplifier,
A ferrite toroidal transformer (a current transformer),
A ferrite magnet.
I recommend you use a current transformer with a ferrite core instead of a simple coil with a ferrite core, because you will a avoid some interferences with the parasitic EM induction from the 50 or 60 Hz coming from the power grid.
When you move very slowly the magnet near the ferrite core you may hear the noise of the Barkhausen jumps.
Hear yourself the Barkhausen noise
Click on the picture to see the video (585 kb)
In the experiment
below, I have used a flat coil (air core) near the ferrite torus
(the current transformer used above).
The flat coil is powered with a 2 Hz sinewave, it is interesting to see how the level of the Barkhausen noise changes Vs the time...
The most interesting in the Barkhausen effect is that there are no magnetic links between the source (the 2Hz flat excitation coil) and the EM induction produced by the Barkhausen jumps inside ferrite toroid core. So, this can be a path to explore for building Free Energy generators due to this non reciprocal effect (see the Bakhausen scalar detector from Bob Shannon)...
Reference documents :
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