Multicoil wiring idea (need help).

Discussion in 'Pickups & Electronics [BG]' started by jmShade, Jan 21, 2022.

  1. jmShade


    Jan 21, 2022
    This is a continuation of my post coming from here:
    Magnets & Copper Wire: A Pickup Building Thread

    The TL: DR version:
    I'm trying to build a pickup that will have 6 modes of operation (reduced from 8+, due to my lack of wiring knowledge) using 3 push/pull (DPDT) pots.
    The 6 modes are hummbucking, "hummbucking along the string", single coil, P-style, reverse P-style, all coils in parallel

    Pasting some stuff from my original post here:

    Switches should operate like so: (excuse the poor drawing)
    Red lines display the connection between coils
    Blue lines are volume/tone controls


    Here's a circuit I've tried to made, but it's probably hard to read and maybe wrong? I don't have a lot of experience with diagrams.
    The LED's symbolize the coils. All resistors would be on a PCB behind the pickups.

    There's more info on this circuit in my first post. Any questions are welcome.

    My questions are:
    Can this be done in a simpler way?
    Do I need a battery since I'm using transistors? Can it be made without one?

    Any help provided is greatly appreciated!
  2. Kinkh


    Dec 11, 2011
    At first glance you might be able to do all the combinations with only 3 DPDT switches, but I kind of doubt it. Then again, I did only give your first drawing just a quick glance, didn't analyse it in depth.

    Regarding the schematic, what are you trying to achieve with the transistors? Are you trying to use them as switches?
    Technically, yes bipolar transistors can be used as switches, but it will definitely require a power supply (some kind of battery) and it will be a bit complicated to get the whole setup correct, especially to to get the to be as linear as possible (not to introduce distortion to the circuit).

    If you want to use electrically operated switches you could go for relays (draws a lot of current, battery would die fast), solid state relays (less current draw, but way more expensive) or use an analogue IC switch. For example a CD4053 chip has 3 DPDT switches inside it, and it was also used to switch guitar pedals as a bypass device.
    For such complex switching, I'd recommend using the CD4053.

    If you want to go fully passive, there might be some custom mechanical switches available, but expect them to be expensive. And you probably won't be able to switch combinations on the fly.

    There might be more solutions to this, but you'll need to be more specific on what you want.
    jmShade likes this.
  3. jmShade


    Jan 21, 2022
    Yeah, I thought that the transistors would act as switches, before I was corrected on my original post on the other thread. I was thinking "DC" instead of "AC"...

    Someone over there also recommended using fever "modes". That would enable me to hook everything up with only 3 DPDT switches.

    A battery is an option, a relay not so much, I think.

    The main part that's bugging me is switching from fig.1 to fig.2 (on my drawing above, those would be the 2 combinations on the left that are controlled with "SWITCH1"). I have no clue how to achieve this without transistors (the way I imagined I could use them, at least), because the coils would just end up being connected at all times no matter what's pressed. Any ideas on how to switch between the two?

    It's really hard to find pre-existing multi-coil wiring setup examples to follow, that are not super basic..

    I'll be building the coils at the end of this week, so I'll probably keep the wires exposed and just test out all the combinations, like they recommended, and just keep the ones that work well. "fig.2" might fall out of the picture completely. Or, if I end up liking all of them, I'll come back here for CD4053 advice.

    I just want to switch between these 5 modes (on my drawing above) with the 3 push/pull pots that I have. The bottom two are essentially the same, so 4 modes. There has to be a way to do this in a simple manner.. :D
  4. dwizum


    Dec 21, 2018
    Ultimately, I think you'll find that there aren't a lot of complicated switching schematics available because complicated schematics often include lots of modes that are totally useless - so, instead, most people build instruments that include a smaller number of switching options, focusing on those which are fairly useful in terms of tone, and fairly consistent in terms of output.

    For a multicoil pickup, the range of legitimate switching options are essentially just various combinations of series and parallel wiring. Some people sometimes try phase switching, but that tends to work better on guitars than basses (since phase switching causes a bigger loss to bass frequencies than treble).

    Switching between series and parallel can be useful, but only to an extent. If you have a lot of coils, and you set up a switching array that essentially allows you to traverse every combo from all-parallel to all-series, you'd likely find that the range in output made many of the combinations unusable. If your coil design is such that all-series is useful, then options that skew towards more-parallel are going to be very low output and very nasally sounding. On the other hand, if your coil design is such that they sound good when all in parallel, your all-series mode is going to be total mud and way too high output.

    Hence, most people try to target a narrower range of options, based on what their preferences are. Then, you design the coil to perform well in that narrower range, and you maybe have two or three switching options instead of a bunch more.

    Or, if you want to just go build a coil and see what happens, you expose all wires on a prototype, then test out your combinations experimentally, and hard-wire a couple switches for the handful of options that work well (or you iterate through different coil designs to get closer to what you want).
    Bruce Johnson, jmShade and Kinkh like this.
  5. jmShade


    Jan 21, 2022
    In other terms, jack of all trades - master of none. Message received!
    It does make sense to have less options but make those that remain SLAP. :bassist:
    Kinkh and dwizum like this.
  6. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    I turn to @rojo412 for these kinds of things. He seems to have a knack for fun bass pickup wiring.
    jmShade likes this.
  7. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    By the way, what is the reasoning behind "humbucking along the string"? I'm not doubting you. I'm just genuinely curious as to what tone this is supposed to produce.
  8. jmShade


    Jan 21, 2022
    It's mostly a leftover from my initial idea, now it's here for testing purposes.

    I've had the chance to hear some string parallel pickups on a guitar, it sounded much more powerful somehow, but that might have been due to other factors. I'm not sure if it would actually make any difference in my case. Since this is a prototype project now, I thought I might leave it in and see what happens.
  9. Kinkh


    Dec 11, 2011
    In theory, wiring pickups in parallel should result in a lower total inductance and therefore a higher resonant frequency. At least that's what I've come to understand form the vast discussions on that topic >.<
    On the other hand, wiring 4 exact same coils (or pair for that matter) will reduce the output signal by 4 due to the loading of each pickup one on another. That's why some basses that use multi coils use active buffering or summing (Wal if I'm not mistaken).
    The humbucking part is just to reduce hum.
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