Motionless Induction
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From: RalfM on 22 Mar 2010 02:22 Hi, let's say there is a magnetic field of a _permanent magnet_, and a fixed/nonmovable induction coil is placed into field. Is it possible periodically to change (ie. "disturb") the intensity of the said magnetic field so that an induction happens without moving the coil and the magnet? Could an oszillator (or resonator?) or a similar electronic method help here to generate induction?
From: Jasen Betts on 22 Mar 2010 02:42 On 2010-03-22, RalfM <rm(a)invalid.invalid> wrote: > Hi, > let's say there is a magnetic field of a _permanent magnet_, > and a fixed/nonmovable induction coil is placed into field. > Is it possible periodically to change (ie. "disturb") the intensity > of the said magnetic field so that an induction happens > without moving the coil and the magnet? Yes. eg by moving paramagnetic or conductive materials nearby. this is the principle of operation of most automotive ABS sensors. > Could an oszillator (or resonator?) or a similar electronic method > help here to generate induction? ??? --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Francois Grieu on 22 Mar 2010 04:57 RalfM wrote : > let's say there is a magnetic field of a _permanent magnet_, > and a fixed/nonmovable induction coil is placed into field. > Is it possible periodically to change (ie. "disturb") the intensity > of the said magnetic field so that an induction happens > without moving the coil and the magnet? Yes; one option is to change current in another nearby coil. Another option (suggested in another post) is to move a piece of ferromagnetic material near the magnet or coil. > Could an oscillator (or resonator?) or a similar electronic method > help here to generate induction? According to the acknowledged laws of physics, there is no hope to "generate" anything out of a permanent magnet and a coil without injecting energy in some way. Francois Grieu
From: Michael Robinson on 22 Mar 2010 14:29 "RalfM" <rm(a)invalid.invalid> wrote in message news:ho72hm$mab$1(a)speranza.aioe.org... > Hi, > let's say there is a magnetic field of a _permanent magnet_, > and a fixed/nonmovable induction coil is placed into field. > Is it possible periodically to change (ie. "disturb") the intensity > of the said magnetic field so that an induction happens > without moving the coil and the magnet? > Could an oszillator (or resonator?) or a similar electronic method > help here to generate induction? The crankshaft posiition sensor in my old Jeep worked that way. The cps contains a permanent magnet and a coil. It sits very close to the flywheel or flex plate, which has gear teeth. When the engine runs the flex plate spins, and each time a tooth moves past the crank position sensor, the iron in the tooth "grabs" the magnetic field of the permanent magnet and jerks it around (or the magnetic field grabs the gear tooth, same difference). The movement of the magnetic field induces a voltage pulse in the coil, which goes to the car's central computer for controlling the ignition and whatnot. This is a bit off the subject, but the Jeep cps in particular is prone to wearing out -- over time, heat and vibration cause the little magnet to weaken. Eventually the magnetic field in the cps gets so weak that it simply won't induce enough of a pulse in the coil for the computer to detect. A simple fix is to put a small cap in parallel with the coil. When the cps in my Jeep wore out I found that .01uF got it running properly again.
From: JeffM on 22 Mar 2010 15:16
>RalfM wrote: >>Is it possible periodically to change (ie. "disturb") the intensity >>of the said magnetic field so that an induction happens >>without moving the coil and the magnet? >> Jasen Betts wrote: >Yes. eg by moving paramagnetic or conductive materials nearby. >this is the principle of operation of most automotive ABS sensors. > Electric guitar strings too. |