I Don't Understand Guitar Wiring: Where's the Circuit?

[RobRed]

I am fighting to get a handle on how guitar wiring works. I am confused. In most wiring that does anything, you see circuits--the wire starts at one place, goes through some components and maybe a switch, and then it comes back to complete a circle.

As I see it, with guitar wiring you have one side of a pickup that is "hot" and/or "live", and which, after passing through pickup selector(s) and a volume pot, goes to the tip connector of your jack. The other side of the pickup is negative and, after passing possibly through tone control pots and caps, goes on to the sleeve component of the jack, which is apparently tied to ground. The other part of the negative side that I find confusing is that every component in the control cavity is connected to that same ground--certainly most of that has nothing to do with producing sound. Generally several pickups are hooked up in the same manner, with some switching options to allow them to run in parallel or series, in phase or out of phase, but with the same ultimate characteristic of one positive end going to the tip of the jack and the negative end being grounded to the sleeve. No circuit is completed within the guitar control cavity.

It would be another thing altogether if I could understand that the circuit was completed in the amplifier to which the guitar is connected, but I am confused there because one wiring guru that I ran into along the way on some web site claimed in no uncertain terms that there is absolutely no current running from the amplifier back to the guitar, unless there is a short somewhere. It would be one thing to say that there is a tiny current, just adequate to convey a guitar signal, and that one needs not worry about getting zapped by it, but it is another altogether to say there is no current going back to the guitar.

Then there is the issue of switches. In most circuits (at least I think so), switches are used to open and close circuits, but with guitar wiring, they do not appear to do that. They simply determine which of the several pickups or individual coils of pickups are active at a given time and whether they run in series or parallel or in or out of phase. Inasmuch as there is no circuit completed, I find it really confusing, for example, to see a switch in a wiring schematic with one terminal going off to ground, for instance. I have more specific questions about switches regarding which I am going to put up a separate thread, but here I will put up one of several switch schematics I have where, without anything resembling a circuit in the picture, it is very hard for me to conceive of why the switch is doing what it is supposed to be doing and what role the connection to ground plays (see Super Switch with HSS).

Can anyone enlighten me regarding what sort of electricity we're dealing with here that does not involve circuits and why the negative pole of the pickups runs to ground rather than to something akin to the neutral pole in household current (where we have hot, neutral, and ground as three separate components, not just hot and ground, and circuits are completed if we want to get anything useful from the electricity.

Thanks in advance for consideration and any assistance offered. Rob R

[Chuck H]

I'll start by saying that what you don't know about electronics has been written in books and takes time and study to understand. I doubt you'll get an answer here that fills in all the gaps for you simply because it would take too much time. Now, that said...

The magnets in the pickups are the voltage source for the "circuit". The coils impedance prevents the needed AC from passing directly to ground and this is why the circuit is not shorted. The ground reference is needed to complete the circuit as this is an AC circuit and could not work without a + and - polarity exchange.

The magnetic field holds the coil at a potential. The vibrating strings alter the magnetic field and also the potential in the coil. It is this difference between the static and altered potentials in the coil that is the AC signal sent to your guitar amp.

[big_teee]

I recommend starting on basic wiring and repairs.
Buy a cheap Multi meter if you don't have one and start checking things on the ohm scale.
You will answer most of your own questions.
Later,
Terry

[RobRed]

Thanks a lot chuck! You know, you hit the nail on the head. I've been reading everything I can get my hands on from guitar wiring sites and a couple of books on the topic, and even reading them with these questions in mind, I'm not finding the answers. For the most part, they just treat you like an idiot and tell you to connect wire A to terminal B, rather than giving a clear idea of what you're actually accomplishing. Perhaps I should have asked instead if someone could recommend a book that would cover the topic reasonably thoroughly?

I do understand and recognize most of what you've said. I know that vibrating a string in a magnetic field creates an electric potential, and that that has the potential to generate an electric current, but where I'm hung up is on the question of where the current is going--again, my main problem is I don't see any completed circuit here. Our household AC current has a much greater potential behind it than the AC current in a guitar, but until you close a circuit by flipping a switch to "on", it is nothing but electrical potential. I am missing how striking the strings and producing an electrical potential in the magnetic fields of the pickups is converted to a useful signal when none of the diagrams show what I can recognize as a completed circuit. Of course I recognize there must be a circuit for a current to be generated, so perhaps what I didn't put as clearly as I might have is the question, where is the circuit closed between the positive and negative poles in guitar wiring? I'm just missing that connection.

[RobRed]

You know, I have one and I keep meaning to pull it out. I don't have all the hardware yet, but it occurred to me that that would be a good approach once I get my hands on the switches and what-not. I haven't used it since I wired my workshop, so it may take me a while to find it. Obviously, I have more experience with electricity than with electronics, but I suspect that is going to change fast! Actually, I suppose I could pull out some of my other electric guitars and play around with the multimeter just to see how things work in them. Of course, it's going to involve the same concepts. Thanks, Terry.

Rob R

[RobRed]

Joe: That was a great idea, but I'm not sure I'm any more comfortable that I've got the answer after doing what you recommended. I actually started out using a single pickup with volume and tone, then a single coil with volume alone, and ended up with the pickup alone. In the first 2 cases, I could readily find a circuit, and I could see obviously how the volume and tone pots influenced the signal through the circuit, but in none of the 3 cases could I see a circuit actually carrying current to the amp, and in the case of the pickup alone I did not see any circuit completed. The fact that in any of these the connections to the jack are positive and negative and nowhere connect is where I'm having trouble. It looks like a potential difference across the jack, but if the circuit is not completed in the amplifier, then I just don't get it. I've uploaded my three diagrams. In the first two, the circuit is marked with red arrows and the part of the wiring (involving the jack), where I could find no completed circuit, is circled in a broken line. In the third, the whole thing shows no circuit, unless I am missing something. I was very happy though to see the completed circuits that I did. That helps me to understand the role that a connection to ground from a switch terminal might have.

Thanks, Rob R

[JoeM]

Well I was hoping to get you thinking about it without the switches pots etc complicating issues. But it wont look like a simple DC circuit where you 'see' current flowing, at least not in the way you may be thinking about it.

[big_teee]

Joe: That was a great idea, but I'm not sure I'm any more comfortable that I've got the answer after doing what you recommended. I actually started out using a single pickup with volume and tone, then a single coil with volume alone, and ended up with the pickup alone. In the first 2 cases, I could readily find a circuit, and I could see obviously how the volume and tone pots influenced the signal through the circuit, but in none of the 3 cases could I see a circuit actually carrying current to the amp, and in the case of the pickup alone I did not see any circuit completed. The fact that in any of these the connections to the jack are positive and negative and nowhere connect is where I'm having trouble. It looks like a potential difference across the jack, but if the circuit is not completed in the amplifier, then I just don't get it. I've uploaded my three diagrams. In the first two, the circuit is marked with red arrows and the part of the wiring (involving the jack), where I could find no completed circuit, is circled in a broken line. In the third, the whole thing shows no circuit, unless I am missing something. I was very happy though to see the completed circuits that I did. That helps me to understand the role that a connection to ground from a switch terminal might have.

Thanks, Rob R

Your red current arrows on the first 2 are not correct.
The whole signal path does not go through the tone pot.
The circuit is from the tip of the jack, to the center of the volume pot, through the Vol Pot, out of the vol. pot through the pickup. Returns on black wire to ground back to the jack. the tone ckt is a secondary ckt, with some current flow that effects tone. In fact to make a very short ckt. if you short the jack tip to sleeve, that is the circuit. when the tip goes to vol pot. when you turn it up and down that determines the current out of the vol. pot.
Terry

[JoeM]

Even though you wouldnt want a guitar with just a pickup and no tone or volume, it would work just the same. Imagine a very high impedance speaker (say 1 meg ohm), that can produce sound even with mv AC, connected between hot and ground. That could be your completed circuit, but in practice you'd have the input stage of the amp getting the signal from the pickup, not the imaginary speaker. (The pickup being an AC signal generator.)

[RobRed]

OK...Now we're talking. It's too late at the moment, but I'm going to have to review those drawings I did today in reverse and look at the tone control part as a separate circuit. I'm still stuck on how we can view it as a circuit if the positive side ends at the tip and the negative side at the sleeve. A circuit has to be closed to function as a circuit. It seems to me that Joe's last comment suggests there actually is a completion of the circuit across the jack in the amp/speakers that the guitar connects to...that makes sense to me. If there is completion of a circuit involving the connection between the guitar and amp, though, then am I mistaken to believe that there must be a current, presumably minute, traveling from the amp back to the guitar? I know that question has next to nothing to do with understanding wiring within the guitar, itself, and I think the outcome of looking at the circuits in the drawings I did in response to Joe's suggestion will help me tie that all together, but I am really stuck on this idea of having a circuit that isn't a circuit!

Thanks, all. I hope I'm not driving you crazy, but I have a tendency to obsess until I understand something. Rob R

[Sweetfinger]

A circuit has to be closed to function as a circuit. It seems to me that Joe's last comment suggests there actually is a completion of the circuit across the jack in the amp/speakers that the guitar connects to...that makes sense to me. If there is completion of a circuit involving the connection between the guitar and amp, though, then am I mistaken to believe that there must be a current, presumably minute, traveling from the amp back to the guitar?

You can think of the input circuitry of the amplifier as completing the guitar's "circuit". This is rarely referenced because it is essentially a given that the guitar WILL be plugged into an amp. If you want to get really complicated there are subcircuits in the guitar that are operating without it being plugged into anything, but there's no need to discuss them much because it isn't really useful to ponder what a pickup is picking up when it isn't connected to the amplifier.

The answer you received about there being no current flowing from the amplifier to the guitar is correct for the general context. The amplifier in no way "powers" the electric guitar. There is a small ac signal flowing BETWEEN the guitar and the amplifier but the signal is generated by the guitar. Even though half the time there are electrons flowing backward into the guitar as part of the ac current, for pretty much all purposes relating to guitars and amps, ac signals(currents, voltages) can be understood to "flow" from the generating point outward.

Some audio IS wired like electrical outlets, with a hot, neutral, and ground. They are called "balanced line". It is possible to wire a guitar this way, but is rarely done.

[Steve Conner]

The answer you received about there being no current flowing from the amplifier to the guitar is correct for the general context. The amplifier in no way "powers" the electric guitar. There is a small ac signal flowing BETWEEN the guitar and the amplifier but the signal is generated by the guitar.

Yes. The situation is pretty much identical to the AC current in your wall outlets, except the current is much smaller.

The pickup is a generator, current flows out of it through one wire, down the guitar cord, through the first stage of the amplifier, back along the other conductor of the guitar cord, and back into the pickup through the other wire, completing the circuit. (Obviously the current is alternating, so half of the time it runs round the circuit in the opposite direction, but it is still the same circuit, and the pickup is always the generator of power and the amp the consumer.)

An amplifier is required because the output from the pickup is too feeble to power a speaker directly. Or put another way, because Leo Fender thought the world was ready for something louder than a Dobro. The pickup supplies a tiny amount of power to the amplifier's first tube (or transistor or whatever) which amplifies it by adding power derived from the wall outlet, then this amplified signal is fed to the next tube, and so on until you have a deafening 100 watt stack.

The confusing mass of volume pots, tone pots and switches fitted to some guitars complicates things, but it doesn't alter the basic principle I described above. They are all just ways of regulating how much signal from which combination of pickups reaches the amp.

There are two basic ways of doing it: An impedance can be inserted in series with the pickup, which makes it harder for the signal to fight its way through to the amp. The extreme example being an open pickup selector switch, which allows no signal at all.

Or, an alternative path can be provided in parallel, that the current will go through in preference to taking the long trip down the guitar cord and through the amp. A tone pot with its capacitor is an example of this.

A volume pot, as usually wired, does both of these things simultaneously.

"Ground" is a fiction beloved of EEs and techs. In reality, everything is a circuit, and every current must have a wire to go out in, and another to come back in. But, several circuits can share a single wire. Ground is one of these shared wires. You can think of it as a kind of meeting place of currents, where a bunch go in, and another bunch go out, but according to Kirchhoff's Current Law they must all add up. If it helps you, redraw the schematic with wires between all the points that had ground symbols on them.

[GaryR125]

Maybe this will help:

http://ocw.mit.edu/ans7870/8/8.02T/f...nce/1_edit.wmv
Think of the meter as the amp.

[RobRed]

Sweetfinger: I'm getting closer and closer to an understanding that fits what I know about things and makes sense to me. That is comfortable. One of the biggest problems that has had me stuck on this (and I will acknowledge I can take things out of proportion to their level of importance and probably have done so here, but they need to make sense to me) is that one writer on another discussion group that I read while just starting to dig into this stuff came out and said, as if in no uncertain terms, that there is absolutely no current traveling from the amp to the guitar. Now perhaps what he meant to say was that there is absolutely no current generated by the amp that runs to the guitar, and that is true and obvious and a good thing to know, I imagine :<) (I recall in childhood some evening serial where a rock musician was killed by a significant current running from the amp to the guitar, and it turned out someone had messed with the wiring in the amp intentionally in order to murder him).

Of course the current we're talking about here is minute, not something that one would even feel, never mind worrying about getting killed by it. But I was stuck because of the stark statement that there was absolutely no current running from amp to guitar, and to look at the positive and negative ends of the circuit just coming to an end at the jack, where they don't tie together until you plug in, does not show what one would ordinarily think of as a completed circuit. I can understand it if folks who wire guitars regularly come to take that concept so for granted and see the current as so insignificant that they don't find it useful to think about it, but I had to hear it straight after being informed that there was absolutely no current. The pickup influenced by vibrating strings generates an electric potential, but until you close the circuit, there is no current. We know we are generating current in the guitar to send it to the amp for processing, so we come to think of it as using the guitar to send a signal to the amp, but a circuit can't be a one-way street (that's why it's called a circuit!). After the amp does its dirty work, some small amount of current has to come back to the guitar. I think I can see the meeting of the male and female jacks as representing a STDP switch, where you obviously need one at both ends of the cord to complete the circuit (and if electrical power generated was only moving from the guitar to the amp, you'd only need a cord with a single wire and a single connection at the guitar's output jack, and that is obviously not the case). It gets silly to say, but we all know from experience you can have the amp turned on, have pickups selected, and bang-away like mad on the strings generating all sorts of electric potential and wonder where the sound is, until you look down on the floor and see that you forgot to plug in.

The one thing you said that leaves me a bit troubled yet, after you acknowledged that there is a tiny current traveling as there must be in a circuit, is "Even though half the time there are electrons flowing backward into the guitar as part of the ac current (saying which, you have acknowledged the circuitous flow of electricity between guitar and amp), for pretty much all purposes relating to guitars and amps, ac signals(currents, voltages) can be understood to "flow" from the generating point outward (by which you seem to want to turn around and deny it)." First, considering that issue on the same scale, we can describe the current that returns from the amp to the guitar as minute, but we have to recall that the current we sent out in the first place was minute too...that's why it had to be amplified! Second, considering the issue on a bigger scale, when I wire up a light fixture in my bathroom, I don't harbor any misgiving that if I turn the light on I'm going to burn down the plant that generated the power. At the same time, I know that if I don't hook up the neutral connection on the fixture to return unused power to the power plant, that light is not going to do anything. While the business end of using a light fixture is to be able to operate a lamp, and we all reasonably think of having power delivered to our house (as if it was all unidirectional, like we're trying to see between the guitar and amp), the return of power to the generator that we don't have much reason to think about in our daily use of a light, in this much bigger context, is an essential part of reality and the physics of utilizing electric power. If there is no completed circuit and no return of current to the generator, we have no light. I have to see guitar electronics as analogous to that, but just on a much smaller scale.

Anyway, my mind is at peace now on this one issue. Now I can get around to studying the business end of the circuit that is within the guitar itself. Thanks.

Rob R

[Steve Conner]

one writer on another discussion group that I read while just starting to dig into this stuff came out and said, as if in no uncertain terms, that there is absolutely no current traveling from the amp to the guitar.

Well, he was wrong, meh. As you say, the whole thing is indeed a circuit, and it's incomplete until you attach it to an amp using a suitable guitar cord.

While the business end of using a light fixture is to be able to operate a lamp, and we all reasonably think of having power delivered to our house (as if it was all unidirectional, like we're trying to see between the guitar and amp), the return of power to the generator that we don't have much reason to think about in our daily use of a light, in this much bigger context, is an essential part of reality and the physics of utilizing electric power.

Well, not quite. Current goes out in one wire and returns in the other, but power flows unidirectionally from the power plant to the lamp. And even though the current alternates, the flow of power is always in the same direction. Current and power are two different things.

This is why people talk casually about "signals" and "power" flowing from the generating point to the point of consumption. Power is the real tangible thing that obeys the laws of thermodynamics and that you pay the utility so many cents per kilowatt-hour for. Nevertheless, the power can't be delivered without that essential flow of electrons arriving through one wire and leaving through the other.

You seem like one of these people who won't be happy until you understand the whole situation, and that's great. But right now it is best just to take this simplified view as true and not think too hard about why. The rabbit hole goes down a long way, and there are horrid things like Maxwell's equations and Poynting vectors lurking at the bottom.

[Jazz P Bass]

Thought I'd jump in here.
You are absolutely correct that there is an "open circuit" in the guitar.
Until you connect it to an amplifier input jack.
The amplifier input circuit connects the loop.
The simplest pickup circuit would be the pickup wires connected directly to the amp input jack.
No volume control. No tone control.
Again, the pickup is "open circuit" until it is connected to the amplifier.

[RobRed]

Steve: It's always comfortable to hear what you wanted to hear in the first place. You've just allowed me to do that and at the same time expressed why I had to see this through. I responded to Sweetfinger's comments before I read your message, and it is interesting to see you put it in terms of the amplifier being the "consumer" and the pickup the "generator", after I made analogy to wiring and using a household lamp, wherein as consumers it is easy for us to forget that if things are not set up for unused power to return to the generator, we aren't going to have any light. Anyway, that question has been answered in a manner that makes sense to me, so it's time to stop beating the dead horse on that one.

You also got the bigger issue that is looming in the background as more important for me to get a handle on, now that I've been able to put the major circuit issue that was bugging me to to rest. I have been studying schematics of wirings using the super switch and the fender S1 switch and recommended wirings of pickups, and there are just things going to ground all over the place, never mind that the hardware has to be grounded just to be grounded (while I think I understand what you mean to say, "Ground" is a fiction beloved of EEs and techs," I presume that part of the grounding actually represents grounding, and that's part of what makes it hard to sort out what's grounding and what is the negative end of some circuit in the guitar's functional wiring). I also find points where it appears that certain connections in a switch simply connect the same wire of a pickup to itself, and I don't see the point in that.

Putting that aside, I find I get confused trying to think through even some very simple component set-ups. Joe recommended yesterday that I look at guitar circuits in very simple contexts, in what I presume was meant to be a very simple and enlightening exercise, and I missed the boat entirely, in part because I was looking for completed circuits and I could not allow myself to include the output jack, simply because I could not see it as part of a completed circuit (for reasons already covered ad nauseum). Now that that is put to rest, I went back and reconsidered the same 3 simple set-ups I did yesterday (pickup alone, pickup with volume pot, and pickup with volume and tone pots) but allowed that the jack is, in fact, part of the circuit.

I think considerations of the isolated single coil pickup and of the single coil pickup with volume control were straightforward, but I am confused regarding the addition of the tone pot. The only circuit I could find that actually connected to the jack did not have any obvious power source. Starting from the tip, it went to the wiper terminal of the volume pot, from there to the end terminal of the volume pot, then to the wiper terminal of the tone pot, then to the end terminal of the tone pot, on through the capacitor and via "ground" to the sleeve. I could not find any way to include the pickup as a power generator, so I did not see what would motivate current to pass through the tone pot and capacitor. Then I found a circuit wherein the current passes from the pickup through the tone pot and capacitor but does not get to the jack, so I was clueless what the point would be in that. I finally put the two together in what looks like a parallel circuit connecting the jack and volume pot through the pickup on one side and the tone pot and capacitor on the other. Plainly this would allow no direct current from the pickup to pass through the tone pot and capacitor, but it leaves me to wonder if the capacitor is not simply seeing the current that makes it through the resistance of the volume cap and acting on that. If I am seeing it correctly, part of the current would be expected to pass through the volume pot unaffected by the tone pot and capacitor, and part would pass through and be affected by the tone pot and capacitor. Perhaps the degree of resistance set on the tone pot determines how much of the current finds its way through that part of the circuit rather than heading back toward the pickup? That seems to make sense. For what it's worth, I've attached all the schematics I created in this exercise.

One more point that mucks up my thinking here...Someone informed me last evening that current passes from positive to negative. You've reported, instead, that in an AC circuit it alternates direction. I guess that's obvious, but it really makes it difficult to see how these components act as filters. When I look at the drawings where the current runs from positive to negative, ironically, even in the simple case of the pickup alone with volume pot, it appears that the volume pot is, in fact, acting on the current returning from the amplifier! If you reverse the flow to go from negative to positive, it appears to more naturally have the volume pot acting on the signal on its way from the pickup to the amp. But then, when you add the tone pot, it gets crazier. Again, if you consider current moving from positive to negative, the tone pot and capacitor are seeing the current after its passed through the volume pot on its way back from the amplifier. On the other hand, if you consider current moving from negative to positive (just reverse the direction of the arrows on my drawing in your head), you still have power returning to the capacitor and tone pot on its way to the volume pot, while current is headed in the other direction to be augmented by the pickup. The current that's passed through and been increased by the pickup meets the current that's passed through the capacitor and tone pot at the end terminal of the volume pot, from where it passes through the wiper of the volume pot and on to the amp through the tip. In that case, again, the capacitor is influencing only a very weak current returning from the amp. If you consider that the higher power generated by the pickup might cause current to run backward through the tone pot and capacitor, then that can only go on to the sleeve, and you've got power going in two directions on the one line. I know that power moves cyclically in alternating directions with AC current, but I don't think that makes this Kosher.

Before I looked closely at these circuits, I thought it all looked simple...the pickup generates power, it goes through the volume pot, then it goes through the tone pot, and then it goes to the amp where it's amplified to produce an audible sound. Now that I've looked closer, it doesn't even look like in that simple case it's all that simple. What am I missing?

Thanks Rob R

[Steve Conner]

It will help if you get into the habit of reading/drawing real schematics.

[52 Bill]

Thank you Steve, I hate discussing things like this looking at pictorial diagrams. In the case of super switches they can be meaningless.

RobRed, the problem that you are having with the added tone controls, is that when you add the capacitor to the mix, you are adding a variable that allows for two different current return paths. The capacitor is frequency limited, so some of the current will be returned through the capacitor side, while some will still be returned through the amplifier side.

[RobRed]

Thank you, Gary. I don't recall enough of electronics to recognize exactly what is going on there, so I don't know how to see it fully as an analogy, but I think I get the general idea. I understand that vibrating a metal wire in a magnetic field (in our context, plucking or strumming a string in the vicinity of a pickup) generates an electric potential, but I don't know how that compares to someone apparently pushing some metal object through a circular metal winding that must be generating a magnetic field. I presume that, too, somehow generates a current, and the meter is measuring the current. The one thing that appears obvious though, as relates to the discussion behind this, is that there are two wires connecting the metal coil to the meter, so again, if we are to compare the meter to the amplifier, the meter does not generate a current, but I presume current does pass through the meter and return to the coil, just as I presumed current passed through the amplifier and returned to the guitar. So I think I'm still on the same page. Let me know if I was supposed to get something else from this, please. Thanks for the URL.

[RobRed]

Thanks for that insight. I got thinking about another useless but thought provoking set up that might shed some more light on this for me. If you kept the cavity open so you could measure current with a multimeter, you directly connected the tip to the sleeve of the jack, and you strummed the guitar to generate electric potential in the pickups, obviously nothing useful (at least musically) would come of it, but would you be able to measure a current? (I may have to try this!)

Rob R

[RobRed]

Wow! I guess I asked for that! I understand that a capacitor's being frequency limited is somehow responsible for its effect on tone, but I haven't got a clue about the physics behind a capacitor being frequency limited or even just what that means, and I have no idea why that would result in current being redirected in part one way or the other.

I just want to apologize to all for the length of these messages. I know they're typically supposed to be short and to the point on a discussion site like this, but I don't know how to be short and to the point with this stuff. Thanks to all for taking me seriously and taking the time to help me sort through this.

Rob R

[Steve Conner]

Well, at least you show evidence of some kind of thought process and interest in the subject, unlike a certain bunch of Analog Electronics 101 students I had to deal with last year.

I don't think even Dick Dale or Pete Townshend could generate enough strumming power to light a lamp, but you should be able to get a reading on a multimeter. I've seen this recommended as a way of measuring pickup output. If strumming doesn't do anything, tapping the pickup poles with a screwdriver will.

[JoeM]

Yes, if you had a meter sensitive enough (set to AC). You can for example also connect directly to a scope and see the generated waveform.

[RobRed]

You hit the nail on the head that time. I think part of the trouble for me with all of this is that everywhere I go on line to look into guitar wiring and in 3 books I've gotten my hands on on the topic (and as you might imagine with the effort I've put in here, I've done a lot of looking), everything is done pictorially rather than by using real schematics. That's part of what I meant in one of these many messages when I said something to the effect that I find it very frustrating in a book or article that is supposed to enlighten you on guitar wiring when they give you a picture and tell you to attach wire A to terminal B, as if you were assembling a child's toy for Christmas, rather than to instruct you on appropriate schematic symbols and how to read and use them. I have been creating these pictures because I don't know, for lack of being able to find them anywhere, the standard symbols to be used in schematics.

I look at the schematic you have offered, and of course once I see it, a good deal of it is obvious. The pickups are labeled as such, they have coils, there are 3 of them here ( ;D ), and they have a wire going off to ground. I have no idea what it means that the ground on the middle pickup is depicted differently than on the other two and that the middle pickup appears to have another wire hanging off into space off to its left. I recognize the capacitor by its position and by the units labeled, but the symbol is not familiar. The pots are obvious (but seeing the grounds laid out in this way makes me recognize that I didn't stop to think earlier of the fact that the signal through the volume pot also goes to ground and how that might have influenced the current's travel--I guess that's a good part of the argument that schematics are better). I must presume 70-250 is the jack, by its position and because I don't see one anywhere else! In the same manner, I guess that 19-351 must be the pickup selector switch, but I haven't got a clue what sort of switch it is, and I am confused because I only see 2 of the 3 pickups connected to it. I have suspicion that some pickup connections to these switches are done through ground, but I don't see a ground symbol tied to the switch. I guess I'm just repeating the obvious--you can't make reliable use of symbols you don't know.

That being recognized and stated, can anyone recommend a good book on guitar wiring (or a book on general electronics that will cover components necessary to the guitar that might not commonly be used elsewhere, like pickups and pickup selector switches) that actually gets into the science behind it and goes as far as to instruct one on the use of standard schematic wiring symbols, rather than using pictures (some of which are frankly awful)? I don't need to be an electronics engineer, but I would benefit from a good general understanding of this stuff. I would love that!

Thanks, again Rob R

[RobRed]

You know, I'm in a different position than those Electronics 101 students. I am retired prematurely due to a physical handicap (I am a family doctor), I've been playing the guitar for about 46 years, I am an avid woodworker, and I've got it in my head that I'd like to start making guitars as part of what I do to keep my head on straight during retirement. My youngest son shares this interest, so I hope it is something we can do together. That being said, you may understand that I am anxious to get more than a perfunctory understanding of this stuff, I have a brain and am used to using it, and I have the time to invest in study (not that I want to invest this much of it in this manner, this regularly, for too much longer , but I can't start wiring until the parts come in anyway!). I also have this annoying habit of being very obsessive about things.

Thanks, again Rob R

[big_teee]

You know, I'm in a different position than those Electronics 101 students. I am retired prematurely due to a physical handicap (I am a family doctor), I've been playing the guitar for about 46 years, I am an avid woodworker, and I've got it in my head that I'd like to start making guitars as part of what I do to keep my head on straight during retirement. My youngest son shares this interest, so I hope it is something we can do together. That being said, you may understand that I am anxious to get more than a perfunctory understanding of this stuff, I have a brain and am used to using it, and I have the time to invest in study (not that I want to invest this much of it in this manner, this regularly, for too much longer , but I can't start wiring until the parts come in anyway!). I also have this annoying habit of being very obsessive about things.

Thanks, again Rob R

Rob:
Hang in there.
Check this out.
I looked at a couple of the lessons, looked great.
Volume I - DC : All About Circuits
When your not beating on guitar circuits, maybe you could go through some of this stuff.
Get your meter out. There's nothing like hands on to learn electronics.
T

[RobRed]

Terry:

Thanks a heap! I checked it out. It looks great. It's in my favorites. I'm getting tired for today, but I'll probably dive in tomorrow! I will get a lot of what I want to know about electronics, but unfortunately when I did a search through the site on "guitar pickups" it sent me off-site, so it does not have the guitar-specific info that I'd also like to have, but this will be a great start to getting a general understanding of the electronics that allow electric guitars to work.

Rob R

[big_teee]

Terry:

Thanks a heap! I checked it out. It looks great. It's in my favorites. I'm getting tired for today, but I'll probably dive in tomorrow! I will get a lot of what I want to know about electronics, but unfortunately when I did a search through the site on "guitar pickups" it sent me off-site, so it does not have the guitar-specific info that I'd also like to have, but this will be a great start to getting a general understanding of the electronics that allow electric guitars to work.

Rob R

Pickups are Transducers. A big Inductor.
So you can look up inductors, and draw that symbol for the pickup.
Like was mentioned before draw the guitar layout like a Skematic, and it will make more since.
The pots are varible Resistors the pickups are inductor transducers, and you have Capacitors and switches.
Later,
Terry

[RobRed]

Good to know. I've made note of "transducers, inductors". Now I'm excited.

Rob R

[Steve Conner]

I just posted the first "real" looking schematic that came up on a Google Images search, and it happens to be for a Gibson Grabber G-3 bass, which is somewhat unfair. I wanted to post one for a Strat, but couldn't find anything but those stupid pictorial drawings.

The "wires dangling off into space" are supposed to symbolize metal shields on the pickups, or to specify that the metal cores of the pickups should be grounded. The intent is to reduce hum.

There are 3 pickups shown, but they are in a weird hum-cancelling arrangement similar to the RWRP on a Strat. The middle one is wired permanently in series with the other two. The pickup switch selects bridge+middle, neck+middle, or all three. The Gibson G3 Bass Guitar

Those "super switches" make my head hurt too.

[RobRed]

I appreciate that. The main issue was the schematic, not the particular instrument, but let me mark up the schematic with some questions and put it up as an attachment, because now that I have a little more of an idea of what it is, I am even more confused (fortunately in a little way, but... ). Maybe if you could respond to these particular questions it would help me get a handle on some things.

It is ironically funny that you mention the super switches making your head hurt, because while I have a hard time sorting out how the connections I see on diagrams of use of the super switch in wiring up a particular guitar do exactly what they are supposed to do, at least I can see a bunch of connections and I can trust someone in the know has mapped it all out and it works. On the other hand, in the "preferred" schematic representation here (as my mark-up will make blatantly apparent), there is nothing that gives me even the least clue as to how the switch is supposed to be wired or even work. It is so symmetric in its appearance as drawn that with only 2 connections demonstrated, and those being in series with pickups 1 & 3, I haven't got an inkling how you can look at that and know it is meant to allow you to choose between B+M, N+M, or all 3. If I saw a schematic diagram with a symbol for a super switch that limited in detail, it would be absolutely useless. Are there not places (as for instance with the use of the super switch) where things are complicated enough that a more diagramatic component can be added to a schematic (I will also attach an image of a schematic-like but plainly not purely schematic diagram of the super switch that I took off a Fender wiring diagram. Would one such as yourself see including a diagram like this in a schematic, to allow indication of more complex connections, as acceptable, useful, or even necessary, or would there be some simpler symbol that would just leave you happily to your own devices to sort out how you would make it work?--I'm not being a wise guy in asking this).

Thanks, Rob R

[Steve Conner]

I'm not sure how to answer all of those questions, so in best politician fashion I'll answer only the ones I feel like addressing.

Why does the shield on PU 2 show no ground symbol? It does. Follow the wire that the shield connects to, past point A, and you come to a ground symbol.

How does the selector switch work? This is a strange symbol, not one of the commonly used ones. I guessed that it was meant to represent a Gibson style pickup selector: a single-pole, double-throw switch where both sets of contacts are closed when the toggle is in the centre position. Indeed, the symbol shows the toggle in the centre position, and both sets of contacts closed, and the bass is a Gibson: all heavy hints.

Questions related to the order of the pickup connection: The order of the wires on the coil symbol representing the pickup isn't particularly clear. Normally it would be drawn such that, if the coils were vertical, the connections nearest the top of the page would have the same relative phases. Assuming this convention, the schematic shows the correct hookup for series hum cancelling. This is why the wires appear to cross in odd ways.

[GaryR125]

RobRed - I think trying to equate guitar wiring with a concept like house current, wall switches and table lamps is not a useful analogy.

The video shows a better analogy - the meter in the video works just like your amp. It reads some humanly-undetectable environmental condition, amplifies it to a level we can detect, and shows it to us. The meter in the video reads electrical conditions in the coil and adjusts the position of the needle. The change in the envniromental conditions is the movement of a magnet near the coiled wire. The power to swing the needle in response comes from a battery in the meter.

Similarly, an audio amp reads minute electrical conditions off its input jack and makes a speaker sound. Power in that circuit comes from the wall and is used to power the speaker.

Hold multimeter probe handles in your hand; you'll get a zero reading (resistance anyway). Touch the multimeter probes and you'll get a new reading. Turn on your amp and you won't hear much cause there's nothing happening. Touch the amp cable with your hands; you'll cause some noise to occur as your hands create a (short) circuit at the probe, and change the resistance seen across the probe contacts. The amp will make some sound even though there is no power in, or coming from your body.

You can repeat this experiment if you connect your multimeter or amp to a wire, or a resistor, instead of your hands. You'll get a steady reading or sound because there is no change in the conditions in the wire or resistor. If you connect your meter or amp to a guitar (a device that provides an easy way to manipulate the external conditions attached to the audio jack) you will be able to detect changes in certain physical conditions, like vibrating strings or touching a pickup with a screwdriver, when read off the input leads.

To sum up, the amp is a detector of conditions in the input jack. The guitar is just a fancy wire across the contacts of the input jack.
HTH, Gary

[Steve Conner]

No, the amp requires power from the guitar to work. Any "detection of conditions" in any system whatsoever requires an interchange of energy. (In order to read the multimeter, photons must bounce off it and enter your eye.)

Granted the amount of power transferred is minuscule, about 1 microwatt for a Pete Townshend power chord. Your body picks up a similar, probably smaller amount of power from 60Hz EM fields in the environment.

Some "detectors of conditions" (transducers) work the other way round. In a strain gauge bridge or resistance thermometer, the power needed to do the measurement is supplied from the measuring instrument. But a guitar pickup is not one of these.