Question on DIY pickup winding. Single String/One Magnet.

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Post by Ferniff »

I hope it's alright if I ask here, I'm not a member of many forums. I asked this question on Talkbass as well.

I'm making a quad pickup, so I need to make 4 individual one string/magnet pickups. Should I still be aiming for a 7k-10k resistance range? Or does it differ if I'm using a smaller magnet. I did a test run and don't see me going past 4k rotations around the magnet before I run out of space. Some info:

Magnet length: 18 mm

Magnet diameter: 5 mm

Wire diameter: 0.0026 inches (42 AWG)


I'm going to copy and paste my conversation with ChatGPT

What's the estimated resistance for the same magnet and wire, but 9000 rotations ?

Certainly, let's perform the calculations step by step:

Total Wire Length for 9000 rotations: Total Wire Length = Circumference of the magnet × Total Rotations Given the magnet's circumference is approximately 15.71 mm15.71mm per rotation and aiming for 9000 rotations:

Total Wire Length = 15.71 mm15.71mm × 90009000 rotations

Calculating this gives us: Total Wire Length = 141,390 mm141,390mm

Convert to Meters: To convert millimeters to meters (as resistivity is typically measured in ohm-meters):

Total Wire Length in Meters = 141,390 mm141,390mm ÷ 10001000 (as 1 m=1000 mm1m=1000mm)

Total Wire Length in Meters ≈ 141.39 m141.39m

Calculate Resistance: Using the formula �=�⋅��R=ρ⋅AL:

Given:
Resistivity of copper (�ρ) ≈ 1.68×10−8 Ω⋅m1.68×10−8Ω⋅m (ohm-meters)
Wire's cross-sectional area (�A) is determined by the wire's diameter (0.0026 inches for 42 AWG wire)
The calculation requires converting the wire's diameter from inches to meters for consistency in units.
Upon completing these calculations, we'll obtain the estimated resistance of the wire for 9000 rotations around the magnet.

Apologies for the delay in providing the direct answer. The estimated resistance of the wire for 9000 rotations around the magnet, considering a total wire length of approximately 141.39 meters (after converting from millimeters), and using the resistivity of copper (1.68×10−81.68×10−8 ohm-meters) is approximately:

�≈2.37 ΩR≈2.37Ω


The approximate wire length needed for one rotation around the magnet can be calculated by finding the circumference of a circle with a diameter equal to the sum of the magnet's length and diameter.

Given:

Magnet length: 18 mm
Magnet diameter: 5 mm
Wire diameter: 0.0026 inches (42 AWG)
Let's calculate the estimated wire length required for one rotation around this shape using the magnet's dimensions.

I'm unable to perform direct calculations here, but I can guide you through the process.

To determine the length of wire needed for one rotation around the magnet based on the provided information, calculate the circumference of a circle with a diameter equal to the sum of the magnet's length and diameter.

Given:

Magnet length: 18 mm
Magnet diameter: 5 mm
Wire diameter: 0.0026 inches (42 AWG)
Calculate the circumference using the formula: Circumference = π × Diameter.
The diameter would be the sum of the magnet's length and diameter.
Divide the circumference by the wire diameter to estimate the length of wire needed for one rotation.
Performing these calculations will give you an approximate wire length for one rotation around the magnet. If you need further assistance, feel free to ask!



I apologize for the misunderstanding. The estimated wire length for one rotation around the magnet, based on the provided dimensions, is approximately 57.13 millimeters.

-----------------------------------------------
Is the AI misunderstanding what I'm asking for, or am I misunderstanding it? I don't understand how it came to 57mm for one wrap around a 5mm pole. I tried it and got around 20mm for one rotation, though it's extremely hard to handle this super thin wire for an accurate measurement.

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Post by bmxguitarsbmx »

My apologies for not reading any of the chat gpt stuff.

DC resistance is not the parameter you want to design for. In general, DC resistance correlates with output, but really it is the number of turns you get on that determines output. Not to mention frequency and transient response...

4k windings of 42awg on AlNiCo is not that much, If 42 awg is the smallest wire you have, that will have to do. Simply wind as much wire as you can fit. Ideally, you will want much thinner wire. I would wire these in series so that the inductance goes up a little bit, but even then, you will likely have a very sharp transient response that needs to be damped with a small value resistor around 47k to 100k in value. If this is a bass pickup, then a sharp transient response is less aggravating. Then again, the resonant frequency may be so high that a sharp transient response is barely noticeable. I do have extensive experience winding individual pole pickups from the 90's, but I didn't own any test gear back then to tell you any numbers. The best pickups I wound had over 10k windings on them if they were alnico and the ones I built with the steel slugs and ceramic magnets were far superior, but even then I was winding 7-9k turns on each one. ALWAYS fighting against a sharp transient response if I was trying to use each coil separately. My dream was to send each string to a different guitar amp. All wired in series can sound quite good though. Hope that is helpful

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Post by mozz »

There a pickup forum on here and here. As was said, try to fit as much as possible in the space you have. 43awg would help but use what you have. They also make .187 magnets(typical fender single coil size). A google search on hexaphonic guitar pickup is bringing up a lot of web pages i never saw before.

https://music-electronics-forum.com/
https://guitarnuts2.proboards.com/

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Post by Ferniff »

bmxguitarsbmx wrote: 19 Nov 2023, 19:49 My apologies for not reading any of the chat gpt stuff.

DC resistance is not the parameter you want to design for. In general, DC resistance correlates with output, but really it is the number of turns you get on that determines output. Not to mention frequency and transient response...

4k windings of 42awg on AlNiCo is not that much, If 42 awg is the smallest wire you have, that will have to do. Simply wind as much wire as you can fit. Ideally, you will want much thinner wire. I would wire these in series so that the inductance goes up a little bit, but even then, you will likely have a very sharp transient response that needs to be damped with a small value resistor around 47k to 100k in value. If this is a bass pickup, then a sharp transient response is less aggravating. Then again, the resonant frequency may be so high that a sharp transient response is barely noticeable. I do have extensive experience winding individual pole pickups from the 90's, but I didn't own any test gear back then to tell you any numbers. The best pickups I wound had over 10k windings on them if they were alnico and the ones I built with the steel slugs and ceramic magnets were far superior, but even then I was winding 7-9k turns on each one. ALWAYS fighting against a sharp transient response if I was trying to use each coil separately. My dream was to send each string to a different guitar amp. All wired in series can sound quite good though. Hope that is helpful
Thanks, I guess this will be a lot of trial and error for me. What it be more powerful if I had two magnets side by side for each string?
This is what it looks like with about 3,000 turns. I 3D printed the piece itself as well as a mount to attach to the motor .
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Post by karul »

Are you making the pickups for bass guitar or something else? First thing that comes to my mind when coil per string are mentioned, is Eberhard Weber and his five-string electric upright bass. I think he had piezo too, but I'm not sure, it's been a while... I think there were some threads on other pickup dedicated forum, discussing it.
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Post by Ferniff »

karul wrote: 20 Nov 2023, 14:24 Are you making the pickups for bass guitar or something else? First thing that comes to my mind when coil per string are mentioned, is Eberhard Weber and his five-string electric upright bass. I think he had piezo too, but I'm not sure, it's been a while... I think there were some threads on other pickup dedicated forum, discussing it.
Yes a bass guitar, to be able send 4 strings to 4 different amps, but also later down the road have a micro computer analyze pitch from each string and send a midi pitch to a synth.

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Post by karul »

Just a thought - if there's enough room in the pu cavity, maybe you can try a humbucker (humcanceling) per string configuration. It can be switchable to single coil and have increased output. And have less noise I guess.

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Post by Ferniff »

karul wrote: 20 Nov 2023, 16:05 Just a thought - if there's enough room in the pu cavity, maybe you can try a humbucker (humcanceling) per string configuration. It can be switchable to single coil and have increased output. And have less noise I guess.
That's a thought. I guess that would involve doing double the work.

I was going to add a buffer to each string, I can probably add some gain from there. It doesn't need to sound the best, just functional.

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Post by karul »

So, partially you are aiming at Phil Lesh's (Grateful Dead) Alembic "Mission Control" Quad pickup and some sort of mini wall of sound and the midi part you've mentioned.
I don't know what types are neck and bridge PUs, but there are noise canceling coils for a reason.

I have no experience with single string pickups so I'll follow your journey.
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Post by Ferniff »

karul wrote: 20 Nov 2023, 20:30 So, partially you are aiming at Phil Lesh's (Grateful Dead) Alembic "Mission Control" Quad pickup and some sort of mini wall of sound and the midi part you've mentioned.
I don't know what types are neck and bridge PUs, but there are noise canceling coils for a reason.

I have no experience with single string pickups so I'll follow your journey.
Correct, but (I think) the neck and bridge work in conjunction with that noise canceling pickup in the middle. I don't think the noise canceling coil was part of the quad pickup setup (which Phil Lesh hardly used during 73/74)

I already made the two state variable filter pickups for the neck and bridge. The only thing I'm missing is a quad pickup. Main focus is to make the pickups first. Then I'll tackle the midi. I do have another bass that has a midi controller I put built and put inside of it.

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Post by bmxguitarsbmx »

I think two coils per string arranged in humbucker fashion is a good idea. Anything to get more wire/inductance.

As long as you are going to install MIDI, you should just plan on damping each coil with a small resistance to get your preferred transient response, and then amplify the signal to suitable levels. A differential design would make sense in the case of hum bucking pickups. You can even string all the coils in series for a passive output and access the individual pickup with a differential amplifier to get your amp/string signal. That is what I did. Though, I never did get the amp/string, I settled on a stereo output with a pan control per string. Back in the 90's there was a company selling individual pole pickups called "Linear Technology" or something. I got coils from him as well. Each coil I got from him was 22kOhm DC. Machine wound with 45 awg I think. His coils sounded much better than mine, but still sounded best all strung in series. That is mostly how I used that guitar because of the transient response of each coil just didn't "feel" good to play.

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Post by Ferniff »

bmxguitarsbmx wrote: 22 Nov 2023, 18:38 I think two coils per string arranged in humbucker fashion is a good idea. Anything to get more wire/inductance.

As long as you are going to install MIDI, you should just plan on damping each coil with a small resistance to get your preferred transient response, and then amplify the signal to suitable levels. A differential design would make sense in the case of hum bucking pickups. You can even string all the coils in series for a passive output and access the individual pickup with a differential amplifier to get your amp/string signal. That is what I did. Though, I never did get the amp/string, I settled on a stereo output with a pan control per string. Back in the 90's there was a company selling individual pole pickups called "Linear Technology" or something. I got coils from him as well. Each coil I got from him was 22kOhm DC. Machine wound with 45 awg I think. His coils sounded much better than mine, but still sounded best all strung in series. That is mostly how I used that guitar because of the transient response of each coil just didn't "feel" good to play.

Thanks, I might look into that in the future. I'm still in the experimental stage right now.
Currently I'm working on designing a larger bobbin so I can have more space for extra windings.

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Post by bmxguitarsbmx »

Yeah man. Most importantly wind and test. Enough talk! I probably dont remember correctly anyway!

The first ones I did used Strat magnets, sections of soda straw and nylon washers with 3/16" I.D. from the local ace hardware store. I know 3d printing has improved a lot in the recent years, but you can't snag the wire at all. Additionally, the closer the winds to the magnet are, the more efficient the pickup will be. If your pickups are low output, that will be part of the reason (leakage inductance).

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Post by Ferniff »

Alright, well I made a quad pickup. It's fragile, and still needs some work and design tweaks, but it works.
Some pics of an earlier version that I had to make some tweaks with.

I'm playing around with an pedal enclosure to control the quad pickup. I have a 4PDT switch, which sends the quad pickup out, or just the neck and bridge pickup.

I want to make a switch that can combine the E/A string pickups together and the D/G pickup together so only two signals are going out. I know things get tricky when you're merging two pickups together, so I'm curious what the best way to approach this is. Currently I just have a DPDT switch.

Unrelated, but I also have two other switches that reverse Out 1 and Out 2, and another switch for Out 3/4. That works at least.attachFull5337638

I just drew half of this circuit which can apply to either String E/A | Out 1/2 or String D/G | Out3/4:
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Post by karul »

Ferniff wrote: 02 Feb 2024, 00:23 I want to make a switch that can combine the E/A string pickups together and the D/G pickup together so only two signals are going out. I know things get tricky when you're merging two pickups together, so I'm curious what the best way to approach this is. Currently I just have a DPDT switch.
Can you be more specific. It would be 2 way or 3 way switch? What will be active on each position ?

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Post by Ferniff »

karul wrote: 02 Feb 2024, 09:02
Ferniff wrote: 02 Feb 2024, 00:23 I want to make a switch that can combine the E/A string pickups together and the D/G pickup together so only two signals are going out. I know things get tricky when you're merging two pickups together, so I'm curious what the best way to approach this is. Currently I just have a DPDT switch.
Can you be more specific. It would be 2 way or 3 way switch? What will be active on each position ?
2 way. Either it's merged with another signal, or each signal has it's own output. The schematic is drawn the way it's currently wired.

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Post by karul »

Do all pickups have same magnet orientation and winding direction, same amount of turns ?

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