The physics behind pick-ups?

[Tom B]

Hi all,
i'm very interested in physics, and my teacher said in class today, that pick-ups have something to do with magnetical flux (if that's correct English..) changing and there by creating electrical stream (kinda like a generator). So are the nickelstrings magnetised? So pick-ups wouldn't pick up nylon string sounds? any info is appreciated.
Thanks

[MetalMedal II]

Simply put, pickups are inductors.

http://en.wikipedia.org/wiki/Inductor

They're also described as transducers:
http://en.wikipedia.org/wiki/Pickup_%28guitar%29

[Ace]

Strings aren't magnetized, the pickups are. There is a magnetic field genetrated by the pickups. The strings are in the magnetic field and when they are picked(strummed, etc...) they disrupt the magnetic field creating an electronic signal.

[charvel750]

But strings are magnetic, and are attracted to magnets. Nylon strings won't be heard on an electric guitar since they're not magnetic.

[mm2002]

Nor will bronze strings Joe. For nylon strings, bronze strings, etc. to be amplified you need a "transducer" type pickup. They sense vibration rather than a disruption of the magnetic field.

[mm2002]

This brings up a good question! What about stainless steel strings? They are non-ferrous, so they shouldn't respond to a magnetic pickup either should they?

[DonP]

Hi all,
i'm very interested in physics, and my teacher said in class today, that pick-ups have something to do with magnetical flux (if that's correct English..) changing and there by creating electrical stream (kinda like a generator). So are the nickelstrings magnetised? So pick-ups wouldn't pick up nylon string sounds? any info is appreciated.
Thanks

Pickups are a mini-generator, made with a coil and a magnetic field going through the coil. When the magnetic field is disrupted (or the coil is moved through the magnetic field), a voltage is generated in the coil. It's the "change" of the magnetic field through the coil that causes the voltage.

The strings are not magnetized, but they could be because they contain iron (doesn't help/hurt anything). When the strings vibrate, they are doing so inside the magnetic field, disrupting it. This creates the voltage in the coil. Non-ferrous strings will not work very well with pickups.

With transducers, the coil moves though the magnetic field mechanically. They are similar in construction to a speaker. When the guitar make sound vibrations (nylon strings will work), the sound waves move the diapham, which moves the coil through the magnetic field, creating a voltage.

Piezo's create voltage with pressure. As a piezo is pressed on (by the strings vibrating on it) it creates a voltage on the opposite sides of the crystal.

[Tom B]

Quote:
Pickups are a mini-generator, made with a coil and a magnetic field going through the coil. When the magnetic field is disrupted (or the coil is moved through the magnetic field), a voltage is generated in the coil. It's the "change" of the magnetic field through the coil that causes the voltage.

That's what i meant with change in 'flux', don't know what the english name is. So the strings aren't magnetised, but they have to be ferro-metal.. thanks !

[HoWheels]

Tom B, here's a good link for you: http://entertainment.howstuffworks.c...ric-guitar.htm

Scroll down a bit, and it talks about electric guitar pickups.

-a

[DonP]

Quote:
Pickups are a mini-generator, made with a coil and a magnetic field going through the coil. When the magnetic field is disrupted (or the coil is moved through the magnetic field), a voltage is generated in the coil. It's the "change" of the magnetic field through the coil that causes the voltage.

That's what i meant with change in 'flux', don't know what the english name is. So the strings aren't magnetised, but they have to be ferro-metal.. thanks !

Flux is the correct term. In the simplest form, just passing a conductor through a magnetic field creates a voltage. I like to think of it as the magnet field / flux "pushing" the electrons through the wire.

[Tom B]

thanks, Howheels. I also read the part about tube amplifiers but i don't understand it completely.

[bratfink]

This brings up a good question! What about stainless steel strings? They are non-ferrous, so they shouldn't respond to a magnetic pickup either should they?

Stainless Steel is a ferrous metal. It is steel after all.

Aluminium would be a non-ferrous metal.

[Zerberus]

This brings up a good question! What about stainless steel strings? They are non-ferrous, so they shouldn't respond to a magnetic pickup either should they?

Stainless steel with a Zero Iron Content? (= "non-ferrous") Not in this solar System, bro