Understanding electronics in a guitar?

[matthew]

DUH! how silly of me, yes of course liamk the string is not the inductor in this case.

as the (magnetic) string moves in the magnetic flux, it will cause the magnetic field to vary. This change in the magnetic field causes the current variations induced in the coil ... although there will ALSO be a small current induced in the string, this is not used - i wonder if anyone has tried amplifying this? I suppose you'd get a lot of noise as the current would be so weak.

[Puff]

This is over complicated.
Liam is on the money. The pickup is an electromagnet being "driven/excited" by the strings. Much like a generator can be had by 'driving' an electric motor and a motor can be made by 'driving' a generator. It is simply shoving the current the other way.
Shove DC current back through the pickup and you have created an electromagnet and you can watch your strings get sucked in. The larger the voltage the bigger the suck. Same happens if you overdo the strength of your pickup magnets or their proximity to the strings.
Most electromagnetic pickup wirings I have come across "ground" to the bridge'.
Martin's analogy of the rock in the pond works in context of locating something else in the same way as pulsed radio frequency waves are used in radar, pulsed sound waves in sonar etc. but I do not see its relevance here. I could well be missing something.
There are much simpler wiring diagrams for just about every pickup and configuration of same so far invented than the colour coded ones earlier in this thread readily available to a conscientious Googler. It's what happens after that that is somewhat scarce.

[Kim]

I agree with Puff its no more complicated than the movement of the string exciting a magnetic field and as far as schematics go there is lots of easy to follow stuff on the net for every conceivable mix and match of pups, pots and switches, you just need to look and follow your nose. The good thing about guitar electrics is that if you manage to stuff it up you will know right away and because the signals are measured in milliamps, then aside from cooking the pots cause you were too long with a hot iron when redoing the job, you can't really hurt anything even if you do get it wrong.

Cheers

Kim

[liam_fnq]

You cant excite a magnetic field any more than you can the queens nickers. (unless if you move the magnet therefore moving the magnetic field).

The strings vibrate. They induce a VOLTAGE into the coil. I think a few of you are getting voltage and current confused.

The only thing being excited are the strings by the pick.

[Puff]

Liam -"excited" is activated. In my days as an engineer a stator/rotor situation was 'excited' by rotation.

[kiwigeo]

This seems to provide a simple clear explanation of how a simple magnetic pickup works:

" So, why does a guitar pickup work? Neither the magnet nor the coil is moving or vibrating -- why do we still get a signal? Any time a ferous material is placed within a magnetic field, it will "warp" the magnetic flux lines. Therefore, when our steel guitar strings vibrate within the field of the fixed pickup magnet, they cause the magnetic field to "vibrate" as well. This creates motion of the flux lines relative to the coil of copper wire and generates an electrical signal."

If the above is correct then:

1. the effect is not one of magnetised strings inducing current in the pickup. The vibrating strings change the flux around the permanent magnet in the pickup and this in turn induces current in the coil around the permanent magnet.
2. my pebble in the pond analogy probably wasnt the perfect analogy but I think its relevant. The pebble is the pickup, the stone is the string and ripples are the flux lines around the pickup magnet.

[kiwigeo]

Puff wrote:

Martin's analogy of the rock in the pond works in context of locating something else in the same way as pulsed radio frequency waves are used in radar, pulsed sound waves in sonar etc. but I do not see its relevance here. I could well be missing something.

You are missing one thing..radar, sonar are active ranging systems that rely on a transmitted signal being reflected back to the transmitting unit.

A metal detector or wireline ranging tool is a passive device...ie a magnetic field is emitted and any object that comes within that field causes a change in the field that is detected.

[liam]

Quote:

now to pick-ups. The coil is stationary. The magnets are stationary. how the hell are any conductors moving relative to any magnetic fields? Are the strings some how magnetised by the pick-up magnets?

Quote:

This seems to provide a simple clear explanation of how a simple magnetic pickup works:

" So, why does a guitar pickup work? Neither the magnet nor the coil is moving or vibrating -- why do we still get a signal? Any time a ferous material is placed within a magnetic field, it will "warp" the magnetic flux lines. Therefore, when our steel guitar strings vibrate within the field of the fixed pickup magnet, they cause the magnetic field to "vibrate" as well. This creates motion of the flux lines relative to the coil of copper wire and generates an electrical signal."

Simple and clear indeed. where is this from? i now see the how the magnetic field and coil can move relative to each other, there by inducing a volyage in the coil.

[kiwigeo]

I typed in "how do pickups work?" into Google and came up with this site:

http://www.guitarnuts.com/wiring/pickups.php

[Tim Mason]

Problem With google is there are too many false articles/info, however this link tells you Seth Lovers point of view, he invented the bucker, so I trust his input. Have a read, long but very interesting!

http://home.provide.net/~cfh/seth.html

[kiwigeo]

Well after wading through all that I found this:

"That’s right, the magnetic field comes up to the stings there and magnetizes the strings. That’s one of the things that most people don’t understand. They figure that string is waving there and cutting the magnetic lines of force. Nuts. That isn’t it. The magnet, all it does is magnetize the string. Now you’ve got a waving magnetic field. And we have a fixed coil with a waving magnetic field to induce voltage. If you want to, take the magnet out. One you’ve magnetized your strings, it will play until the string loses it. Players think the string, the magnetic field from the magnet comes up to the string and by twisting the magnetic flux back and forth that’s what induces the voltage. That’s not what happens. There’s a certain amount of that, but that’s minor. What is happening is you have a magnetic field that is moving back and forth across the coil. And when you move a magnetic field back and forth across the coil you induce voltage. If you move the field up and down it wouldn’t induce any voltage. It’s the motion back and forth across the pickup that does it. "

So here we have two conflicting explanations of the process going on in coil/magnet guitar pickup. Now THATS interesting.

Ok Ive been up all night here at work and its a bit quiet so Ive spent a good 2-3 hours googling myself crazy. The bottom line is that 99% of the hits disagree with Mr Seth's explanation of how a pickup works.

Mr Seth agrees that the affect of the string on the magnetic flux around the permanent magnet does contribute to the signal but maintains that its only a minor component compared to the signal generated directly in the coil by the magnetised string. This is something thats needs to be investigated further to settle the argument.

[Tim Mason]

Interesting stuff isn't it! I imagine the voltage produced by the strings magnetic flux induces more voltage to the coil than the the magnets flux being manipulated by the string

[Puff]

Yes it is perfectly possible 99% of us are wrong. Actually I think the percentage would be markedly higher than that.

[Puff]

Quote:

Interesting stuff isn't it! I imagine the voltage produced by the strings magnetic flux induces more voltage to the coil than the the magnets flux being manipulated by the string.

This is not interesting it is gobbledeeegook.

[liam]

Once again google has the answer. Just a matter of wading through all the crap to find it. of course what the right answer is is still debatable.

From the start I said I suspected the strings are being magnetised by the magnets. Waving their own magnetic field past the coil induces a voltage. I still find this theory easiest to swallow. Been wrong before though.........................just ask the missus.

[Puff]

AAAaaagghh.

[Puff]

Puff wrote:

Interesting stuff isn't it! I imagine the voltage produced by the strings magnetic flux induces more voltage to the coil than the the magnets flux being manipulated by the string.
This is not interesting it is gobbledeeegook.

Yeah well, gobbledeeegook or not its good to hear the patent creators point of view. Thats good enough for me. Cheers for the other theory's though, definately not canceling anything out

[kiwigeo]

Puff wrote:

This is not interesting it is gobbledeeegook.

That's a matter of opinion.

I find it rather refreshing to see a young person with ambition and a drive to understand the world around him and go somewhere in life instead of spending all day plugged into his iPod and spongeing off his parents.

I cant truthfully say I really understand exactly how magnetic guitar pickups work and this thread has got me very interested in the subject.

[Tim Mason]

Thanks kiwigeo, ill continue on with the pots in a guitar, but i have some work to do, the suns not even up yet and i am, so coffee and neck sanding

[kiwigeo]

Despite all the various posts asserting same I am yet to be fully convinced that the movement of magnetised strings is the primary means by which a magnet pickup works.

I spent another 2 hours tonight trawling the internet and again the vast majority of sources I came across it was maintained that the alteration of the flux around the permanent magnet in a guitar pickup is what generates the signal in the pickup coil. The sources include a number of pickup makers and people ...you'd think they'd know how a pickup works.

Here's a link to an a article by a guy who's an Electronics Engineer and to me he seems to know what hes talking about.

http://www.moore.org.au/pick/01/01_strt.htm

One question I have is this....a magnetised string with a tiny mass of metal compared to that of the pickup magnet would have a much weaker magnetic field around it then the field around the pickup's permanent magnet would it not?

If this is the case then I would ask the question how can a string with a relatively weak magnetic field around it directly induce a current in a coil that lies in the much stronger magnetic field that surrounds the pickup magnet?

[Tim Mason]

Yeah, there are two theorys going on out there it seems, both very similar and i wont cancel one or the other out, but i do understand the method behind both analogys, good post kiwi

[jeffhigh]

Don't you know Martin it's really just Black Magic, you need to know the correct incantations and which small animals to sacrifice.

As far as Seth Lover's theories, I have no idea, but over the years in all sorts of fields , I have found a very poor correlation between someone finding a method that works, and them actually understanding what is happening.

[Kim]

jeffhigh wrote:

As far as Seth Lover's theories, I have no idea, but over the years in all sorts of fields , I have found a very poor correlation between someone finding a method that works, and them actually understanding what is happening.

+1

[kiwigeo]

jeffhigh wrote:

Don't you know Martin it's really just Black Magic, you need to know the correct incantations and which small animals to sacrifice.

As far as Seth Lover's theories, I have no idea, but over the years in all sorts of fields , I have found a very poor correlation between someone finding a method that works, and them actually understanding what is happening.

Well Ive got 4 days of wireline logging ahead out here at work. One of the tools is a mag resonance tool with a huge (70kg) permanent magnet. Ive got a couple of packets of Martin medium guage strings with me so I'm going to rig up a little experiment......its going to be the biggest baddest most powerful guitar pickup ever built.

[Kim]

That would be a Moefoebucker Martin