Re: 6 "piece" PU's


"David Enke" <putw@xxxxxxxxxxxxxxxxxxx> wrote in message
news:t4GdnaV_TqV6UeneRVn-jQ@xxxxxxxxxxxxxxxxx
>
> "Jon Slaughter" <Jon_Slaughter@xxxxxxxxxxx> wrote in message
> news:11n9giq593tuv15@xxxxxxxxxxxxxxxxxxxxx
>
>> Wouldn't this just add hum to the pu? i.e. you have two coils one will
>> induce a current in the other... the current frequency is proportional to
>> the flux frequency... the PU coil will pick up that changing flux and it
>> will induce a current with that frequency into the coil?
>
> Hi Jon,
> The basic electro magnetic current would be flat DC, so no hum would come
> from there. If a portion of the string's signal is fed back onto the DC
> current, then the added resonance would only be created at the vibrating
> frequency of the string and nothing more (in a perfect world).
>
Yeah, I see now. Basicaly the DC current in the coil creates a magnetic
field that isn't changing that "supports" the original pole's field but
since its not changing it won't mess with the PU's coil. Just like why a
transformer won't do anything with DC(but it will make the magnet stronger I
suppose. (I think I fogot that DC through a coil did anything... crap... I'm
loosing it all ;/)

I think the issue then is that what happens with stray fields that are
induced into the EM coil? Surely the string will have some effect on that
coil. So technically its not completely DC... but I think the effect is
similar. Maybe the analysis is to complicated for me until I review all the
basics.

Its a lot easier just to do it then try to figure out how it will work ;)


>> If I'm right basicaly you will introduce that frequency that the EM is
>> driven at into the PU coil.
>>
>> Basicaly its the exact same idea as a transformer except that you also
> have
>> a moving wire generating another current in both wires.
>>
>> i.e. It seems as what you saying is that you have two coils,
>> ||
>> ----
>> ---- PU coil
>> ----
>> ||
>> ----
>> ---- "EM" coil
>> ----
>> ||
>>
>>
>> where || is the magnet(or metal since we will create an EM from it)
>>
>> but this is really just a transformer. And as you probably know that they
>> are used to "transform" an alternating power source's "strength"...
>
> Yes, but the primary field wouldn't alternate. The alternating field would
> only be introduced on a string to string basis, and would need to be a
> tightly controlled representation of the string's output signal.
>

yeah, but your primary coil(the driven coil?) is the same as just a normal
PU coil that has a voltage source attached to it? In the sense that it will
still pick up induced currents from the string... since it is a constant
voltage source(assuming) the current will change and cause the induced
magnetic field to change which will cause the secondary coil's strength to
change. right?

It seems to me that you basicaly have two coils in near proximity both with
driving power sources on them(one happens to use a mechanical process to get
its power(the string) and the other a battery(or it could be mechanical if
you used an outlet to get your power)). But both coils will interact with
each other and since the string will actually drive both coils(but one more
than the other due to distance).


then look at how they interact... Since there is no true DC going trhough
the primary coil you will have some sort of transformer like situation and
depending on turns ratio and such you will get different results.

Seems pretty complex though. Much easier just to try it ;) I'm not to sure
though. Maybe I'm getting something wrong. Maybe this weekend I'll get some
time to read over magnetic circuits and stuff(probably need to review some
EE stuff too).

>> > I'm aware that the current required to drive the coils would likely
>> > require
>> > an off-board power supply, but this shouldn't be much of a problem if
> the
>> > guitar comes with a power supply box (I know, tacky, but.....)
>> >
>>
>> Well, I think this might be the least of your problems(maybe). You would
>> have to cancel that hum(if I am correct about it being there).
>>
>> I think this might be easy though.
>>
>> Its just like what a humbucker does.. except this time instead of the
>> "extraneous" induced current we do it in purpose.
>>
>> hence you turn the coil in the opposite direction and induce the current
> in
>> both then add the signals together on the output. (which gives a weak
> signal
>> I think).
>
> Yes, like how a balanced cable cancels common mode interference.

Yeah, Theres always ways to fix those problems usually.

>> or, even better, you invert the EM generated signal and add it to the
>> original. It should atleast remove the fundamental. I'm not sure if there
>> are any other factors involved that will cause problems.
>
> Yes, adding a phase switch to the driving signal would yield some
> interesting results as long as it wasn't exactly 180 degrees out of phase
> (then you get nadda).
>

Well, depends. Idealy if you can get two sources for the signals such that
one has the two in the same polarity and in the other source in opposite
then you can recover the signals perfectly. Then you can just subtract the
two and get one of the signals and add to get the other(twice the amplitude
ofcourse). i.e. this would be the case if you driven both coils at the same
frequency but flipped there orientation to each other. Then you could
"completely"(theoreticaly) remove the driven frequency from the signal.


>> It might work though using something like that. I'm not sure how much
> power
>> it takes to make an EM magnet though but I think I remember doing nails
> with
>> just a 9v(with a signal generator from DC to AC).
>
> It should work straight off the battery too.
>

Yeah.. I keep thinking about trasformers for some reason ;/

>> > In more detail:
>> > Each driver coil would have its own trim pot so the magnetic field for
>> > each
>> > string could be balanced to the other strings, and the supply current
>> > to
>> > all
>> > the strings would be controlled by a six channel VCA (voltage
>> > controlled
>> > amplifier chip). This 'magnetic gain control' would consist of a simple
>> > pot
>> > that would send a voltage control signal to the VCA. This pot could be
>> > located on-board, or off-board in a foot pedal allong with the power
>> > supply.
>> > The range of tone possibilities would be immense by being able to
>> > adjust
>> > the
>> > magnetic field strength (on the fly) I would think.
>> >
>> > Where things become VERY interesting is when a second foot pedal is
>> > used
>> > to
>> > control how much of each string's AC output gets fed back and boosted
> into
>> > the driving current of another pickup's electro-magnetic coil that's
>> > located
>> > under the same string. This control would use a string's signal to
> 'pump'
>> > the magnetic field of another pickup, and drive the string into
>> > saturation.
>> > Tone filters could be added to the 'insert' signal to enhance the type
> of
>> > feedback desired.
>>
>> hmmm. Maybe. I can't imagine off hand exactly what the result would be
> but
>> it might end up with some interesting results. Maybe one can use it
>> simply
>> for increasing sustain though.. Maybe to much would just result in a
>> feedback mess.
>
> I'm sure that would be the case at a certain point!
>

yeah... it who knows what the possibilities are?

>> Have you tried to work out the theory of it? I would be intersted in
>> knowning the outcome but I don't think I could handle it at this point.
>> I
>> haven't done much electronics in several years and never was that great
>> at
>> AC stuff. (Although it was never the math so much as just having
> experience
>> with it. And all my knowledge/experience was basicaly theoretical since
>> I
>> learned it in class.).
>
> I tend to avoid the math as much as possible, and go straight to
> breadboarding if I can.
>

Heh, its the easiest way. I don't hav ea problem with the math, its just
trying to figure out how all the stuff works since its been about 8 years
since I've learned about all that stuff. The main problem though is when
"learned" we never really got to mess with it. It was all theoretical... No
pratical experience to burn it into memory... which is how I work.

>> > I know it might sound complicated, but the electronics are not. I
> thought
>> > of
>> > doing this *quite* a long time ago, but other things happened and made
> me
>> > quite busy :)
>
>> I think I get the big picture but at the moment I can imagine exactly
>> what
>> the result would be. It seems to me that in the first part you would be
>> increasing the magnetic strength of the pole which should increase the
>> induced current into the PU coil(but would also induce a current into the
> EM
>> coil too, but won't matter). By feeding that signal into another EM coil
> on
>> some other PU then you effectly are increasing that PU's strength by
>> using
>> the other PU.
>>
>> i.e., if I understand correctly if you play a note it will be picked up
>> by
>> one PU and the more its picked up it will drive the other PU even more.
> But
>> its not a constant drive since it depends on the amplitude of the
> note(which
>> decays ofcourse).
>
>> What I imagine is that you will get a very "punchy" sound. Instead of
>> simply exponential decay(if thats what it is), it might be something that
>> decays much faster.
>>
>> (but thats assuming the original note decayed exponentially).
>>
>> I might try to work it out though just to see.
>
> That's the fun of it all, as long as you don't blow up your basement!
>

Heh. One reason I don't mess with AC. To afraid of Electrocuting myself.
Was thinking about playing around with making transforms to see how they
work but I'm always afraid of what might happen... While I think its not all
that dangerous as long as you don't do nothing stupid, sometimes I do stupid
things so ;/

>> > Jon, Mattia, others,
>> > thanks for posting and re-kindling my interest in pulling this concept
> out
>> > of the mothballs. Most likely, it would take a community effort to put
> all
>> > the bits together, but that's why I had no problem with sharing the
>> > idea
>> > here.
>> >
>>
>> heh. Cool. Its fun stuff to mess around. I think there are all kinds of
>> ideas. Its jsut a matter of getting the ones that aren't patented ;)
>>
>> > Clifford,
>> > I don't know if you've read all the patents you mention, but if so,
>> > have
>> > you
>> > seen this anywhere, or is it completely nuts?
>> > (Comps & consulting perks for your time).
>> >
>> > David Enke
>> > Pick-up the World
>> > www.pick-uptheworld.com
>> > 719-742-5303
>> >
>> >
>>
>> Do you happen to have an electronics simulation program? You might be
>> able
>> to enter this in fairly quickly and get some results. I have them
> somewhere
>> but not sure. It might be a cool idea. Personally I think any time
>> something that has potential is cool. Ofcourse the outcome might not be
>> what you thought be who knows... maybe better or maybe just need to be
>> modified.
>>
>>
>> Let me know if I'm off base on the idea.
>>
>> Jon
>
> I don't have a program as you describe. I tend to simply dive into the
> trenches, and then further refine the results if I need to. One of my
> current projects that has been going on for many years is called the
> 'Hybrid
> Polymag'. It's a great idea (in concept) that uses micro neodymium magnets
> to sense string movements and transfer this energy directly into a piezo
> type polymer film material. It is a magnetic pickup, but there are no
> coils
> in it, and the prototypes come in about 1/8" tall and weight next to
> nothing. The main variables have to do with the flux density of the
> magnets
> combined with the mass to frequency ratio of the moving magnets, and then
> this is mixed in along with the variable of the surface tension and size
> of
> the polymer film. I can't imagine a program that could model the
> interaction
> of all these things, so the result is that I'm perpetually tinkering with
> them (argggggg, but not really!).
>

heh. How does the magnets transfer energy into a piezo? The piezo works
directly by converting "pressure" into electrical, right? Is the piezo
material susceptible to a magnetic field?

Yeah, those things probably are not modeled easily and you'd probably need
some custom software to get some ideas. Might not be all that hard either...
some of these programs can do some amazing things(although I haven't messed
around with them in years).


> David Enke
> Pick-up the World
> www.pick-uptheworld.com
> 719-742-5303
>
>
>
>

Jon

>


.

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