The reference thread for newbies!

[Biarnel]

Hi all, this is my first post.
I'm an italian luthier, and right now I'm going to step in the pickup winding world.
Internet offers lot of sources, but I wasn't able to find something to use as a reference.
- I mean, which magnet size, coil size and winding of AWG42 do I need to make a "regular" p-bass split coil? And what for a jazz style one?

I did find more informations about guitar single coils and humbuckers, but very few about bass singles, split coils, humbuckers etc.

As a first try I made a p-style with 2 coils, 7500 turns each, AWG42, AlNiCo V rods 2cm tall, 1cm diameter (one rod per string); Reverse wound reverse polarity, wired in series or in parallel.
The result was something "working" but at a veeeeery low volume. The DC resistance of each single coil is around 1.8kOhm

Where is the mistake?

I have a lot of 10mm dia. / 20mm tall alnico rods, so I'll stick with them, not using 5mm dia. rods. How will this affect the coils? Should I give them more turns?

As a bobbin flatwork, I used 3mm thick clear acrylic: this gave me a coil that is not very tall at all. I thought that would be good for a p-style: squat, large coils. Am I doing right?
What would you suggest as flatwork? Will 1.8mm or 1.5 mm normal black plastic (PVC) suit good (it's a bit floppy...)?

I know these are a bunch of questions, ..in bad english, but maybe the thread will develop in something interesting to be hold *sticky* in the forum.

Thanks in Advance

[madialex]

You have a short in the coils. Most likely it is at the ends somewhere where the magnets go through the bobbin, there was a good thread about that a while back here. What happens is when you wind, the coil wire will actually get between the magnet and the bobbin top or bottom and short out. You should tape over the magnets and really good at these points. I dip mine now in lacquer and when dry then I tape. May be overkill but at least I stopped having shorted coils.

Also watch your tension, things like where you stop to check the resistance when yo strip the wire, make sure it is re-sealed or it can short. And last but not least, get some sort of magnetizer. I use the 1 inch earth mags from stew mac.

[kevinT]

I always point new folks to Stew Mac. I think they have some great info on the construction of buckers and single coils as well as other stuff.

http://www.stewmac.com/freeinfo/

[Biarnel]

You have a short in the coils. Most likely it is at the ends somewhere where the magnets go through the bobbin, You should tape over the magnets and really good at these points. I dip mine now in lacquer and when dry then I tape.

I used loctite cyanoacrylate all around the points where the mags go thru the bobbin, let it dry well, then taped the mags with that thin white teflon non sticky tape. So I really don't think it's a short in the coils.
Anyway, two different coils, same specs but RW/RP... and I have the dame DC resistance. Those would be 2 different values if it was a short.

Am I winding with too few turns? I read p-bass pu are around 10000 turns, but I use 10mm mags, one per string, so the specs should differ.

Any ideas?

[chevalij]

When you meter them, what configuration are they in (parallel, serial). Or are they out of the circuit. I think if you are measuring them in circuit, your switching could be the trouble.

[Biarnel]

nonono, the measurements are done with the coils taken apart from the rest of the electronics.
That is, take a p-style pickup; take ONE of the split coils: put an ohmeter on start and finish of the finished 7500 turns coil. My reading is 1.8KOhm EACH SEPARATED coil.

just to be sure I have no shorts on the mags, i tried testing the coil start and the mags, and they are high impedance: so no short.

[Dave Kerr]

Resistance is futile!

Figure your average turn circumference, multiply by number of turns, and refer to the chart for reasonableness.

[mick]

I would think that if you are getting a reading from your coil start and your mags that you do have a short , I also wouldn't think that the teflon tape would be the best tape to use to try to protect against this..

Mick

[David Schwab]

That is, take a p-style pickup; take ONE of the split coils: put an ohmeter on start and finish of the finished 7500 turns coil. My reading is 1.8KOhm EACH SEPARATED coil.

That's not right. They should be about 6+K each. That does sound like a short somewhere.

I wind 1500 turns of 42 awg and I get 1.47K. Something is amiss.

I use white paper tape before I wind.

[mkat]

I use white paper tape before I wind.

Is that masking tape or a softer type? I've seen a really soft kind of paper tape on bobbins before, but haven't seen that tape in stores.

[Biarnel]

Very nice page, Dave Kerr! It's on my bookmarks now.

Well, 7cm cf., 7500 turns, it's 52500cm, so it's 1722ft approx.
With a AWG42 the table says 1659Ohm per 1000ft.
My coil is 1800Ohm, so it's more or less correct. I think I have to give it MORE turns.

Anyway this means my coils don't have shorts
(and the fact that the ohmeter reads an open circuit testing le coil start and the mags confirm that)

Someone would suggest how many turns should I give to this coil?

[Biarnel]

That's not right. They should be about 6+K each. That does sound like a short somewhere. I wind 1500 turns of 42 awg and I get 1.47K. Something is amiss.

Sigh.
This is not what the table Dave Kerr posted says: AWG42, 1659 Ohm per 1000 feet.
I'm really confused now.

As I stated before: if I had a short, I would have readings of some KOhm from the start to the mags, and it's not my case.
Am I right or wrong?

Is it clear that my coil is a small, 2-string coil? 7cm of circumference.

+-----+
| O  O |  +-----+
+-----+  | O  O |
            +------+

That's it

[Stan H]

Do both coils have the same DCR reading?

BTW, I've scoured the web for good bass pickup references as well. Doesn't seem to be much out there, everything is geared toward guitar...

[madialex]

Well, 7cm cf., 7500 turns, it's 52500cm, so it's 1722ft approx.
With a AWG42 the table says 1659Ohm per 1000ft.
My coil is 1800Ohm, so it's more or less correct. I think I have to give it MORE turns.

Anyway this means my coils don't have shorts
(and the fact that the ohmeter reads an open circuit testing le coil start and the mags confirm that)

Someone would suggest how many turns should I give to this coil?

With a AWG42 the table says 1659Ohm per 1000ft.

Right, and the math you are doing is for a coil with 1000 ft, I'm just guessing here but i'd say 7500 turns is a wee bit more than 1000 feet. The coil is screwed no matter how you slice it!

7500 turns should be somewhere near 6K give or take a little in series correct? Is that how you are wiring the 2 coils?? or parallel?? Parallel you divide right?

In a humbucker, say a PAF style you have approx 4500 to 5000 turns per coil, the whole thing should OHM out somewhere near 8 to 9K meaning each coil is somewhere around 4 to 4.5K .

If you know you are right why come here and ask any of us??? Then we try to tell you what is happening and you disagree. I say figure it out yourself!!

[mick]

I thought that you should get no reading at all from the start to the mags?? if you get a reading then you would have a short , which means that your insulation is being cut through against the mags , maybe you should go back through some of the earlier posts regarding this matter , I would be more concerned about this than about how many turns give you what reading , because it won't really make any difference if your coils are shit..

Mick