Yet another wiring question

[JHN]

Goes as follows;
1 master volume,1 master tone.
Now the tricky part.
There will be a single P-Rail pickup in bridge position.P90 at the bridge side,rail towards the neck.What I would like to achieve is a center detented potentiometer that goes from p90 side to both in series in the middle to rail side.
I would like the master volume to give the equivalent effect of a 500k to the end result,and intend to use a .022 cap for the tone.
How can I do that?What kind of pots should I look for?How should I wire it?
Thanks

 

[Zacker]

Re: Yet another wiring question

I don't know what you want in the 'series in middle of pot' thing but if you want a pot to split the pup, do the Spin-a-split thing

 

[JHN]

Re: Yet another wiring question

The problem is with a Spin-a-split I would loose either the P90 or the rail side,and I would like both,plus the classic humbucking in series sound with the inbetween "play" to either side of the pickup,can't be obtained from a 3 way toggle.

 

[Funkfingers]

Re: Yet another wiring question

If your pickups run in series at the centre detent point of a balance pot, logically, they must also be in series along the entire resistance track of that pot.

What can work is the two coils, in parallel, via the balance pot. Series interconnection would have to be achieved via a DPDT mode switch. (This could be thought of as a Loud Mode switch.) In series mode, the balance pot would be entirely bypassed.



EDIT - On reflection, the mode switch may need to be a 4PDT on/on switch. Wiring this up could be tricky but worthwhile. Keeping all of the wire runs within the outline of the switch would avoid any possibility of strain or trapping damage.

 

[JHN]

Re: Yet another wiring question

Yes,I kinda thought about the balance pot and switch situation,but I want to avoid the in-parallel sound at any ratio of the coils(except when completely each coil on it's own) .What I want to achieve I think could work thinking along the lines of Center - humbucker in series,turning left - gradually removing the p90 side,turning right - gradually removing the rail side,effectively giving a spin-a-split for each coil of the pickup,whereas the middle detent would be common.This is too much of a brain-twister for my mediocre knowledge in electronics.Maybe a pot like the tbx one with different Kohms?

 

[JHN]

Re: Yet another wiring question

Hmmm,my head hurts from thinking about it but I imagine if someone has the answer to this,then the problem will be solved.Can the function of a 3 way on-off-on mini toggle,as it works within the diagram of http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=2_prails_1v_3w_mini ,be emulated with a dual pot (à la TBX) of say 500k and 500k?Take into consideration only one side of the mini toggle,as I am interested in using it for a single P-rail.I imagine the pot would be something similar to this http://www.amazon.com/Bourns-Blend-Balance-Guitar-Potentiometer-Knurled/dp/B005G3WK22.Maybe Black cable straight to master volume,and then use upper deck to send red and white to master volume when turning the pot one way,and use lower deck to send red and white to ground when turning the opposite way?Sorry if I am getting hard to comprehend,English is not my native language.

 

[beaubrummels]

Re: Yet another wiring question

It won't work. You need center-off and the center detent of a pan/blend pot is both on, so you will simultaneously send the series link to both hot and ground.

 

[DreX]

Re: Yet another wiring question

This might work, I haven't tried it before

 

[DreX]

Re: Yet another wiring question

Also you mentioned TBX, note that a TBX is not a typical dual gang pot, it's very particular in what it does.

 

[JHN]

Re: Yet another wiring question

It won't work. You need center-off and the center detent of a pan/blend pot is both on, so you will simultaneously send the series link to both hot and ground.

I don't know the exact workings of a pot,but is there a chance that if I go into the pot from opposite terminals (3 instead of 1) it would reverse the function,effectively turning it to what I would probably need?

 

[JHN]

Re: Yet another wiring question

Also you mentioned TBX, note that a TBX is not a typical dual gang pot, it's very particular in what it does.

Yes,thanks for mentioning that,and also thanks for the schematic,this is about what I thought would work,only question is if I can achieve the effect needed i.e.blocking the series link from going both to ground or hot when in center detent position and allowing it to pass when on either side of the pot where it is needed to.

 

[beaubrummels]

Re: Yet another wiring question

I don't know the exact workings of a pot,but is there a chance that if I go into the pot from opposite terminals (3 instead of 1) it would reverse the function,effectively turning it to what I would probably need?

Swapping the wires won't reverse the function of the pot. Here's what we're talking about:

Using a SPDT on-off-on switch;
lug 1 - ground
lug 2 - red/white
lug 3 - hot
...in the center position, red/white are only connected to each other, making it a humbucker.

Scenario 1 - pan/blend pot
lug 1 - ground
lug 2 - red/white
lug 3 - hot
...in the center position, red/white are going to both hot and ground

Scenario 2 - pan/blend pot
lug 3 - ground
lug 2 - red/white
lug 1 - hot
...in the center position, red/white are still going to both hot and ground

A pan/blend works like this:
It's two pots stacked on each other
the resistance material / taper for the top pot is only on half of the travel of the pot as it rotates, say from between 1 - 2
the resistance material / taper for the bottom pot is only on the other half of travel (opposite half from the top pot), say between lug 2 - 3
While you are turning the pot from the center to one side, only one pot is applying resistance to it's signal, the other pot is doing nothing - it's full on/open.
When in the center, both pots are fully on/open.

 

[Artie]

Re: Yet another wiring question

This might work, I haven't tried it before.

I did. It didn't work worth a darn.

 

[DreX]

Re: Yet another wiring question

Yes,thanks for mentioning that,and also thanks for the schematic,this is about what I thought would work,only question is if I can achieve the effect needed i.e.blocking the series link from going both to ground or hot when in center detent position and allowing it to pass when on either side of the pot where it is needed to.

I have to admit, I'm not sure what you want to have happen at center. A 500k dual gang linear pot like this should give you series at center http://www.ebay.com/itm/2-x-500K-OH...840?pt=LH_DefaultDomain_0&hash=item4ac01e5f40 , because at center, there would be 250k resistance from grounding out second coil, and 250k resistance from bypassing the first coil, hence it would be in series. In this case, true center (5 on the dial) might not be the most perfectly series, a center detent might be pointless, but also, the "on center" sound might account for most of the sweep anyway. The reason is that 500k (or 250k resistance on either side) might or might not be too much, so I'd also buy a 250k linear dual gang http://www.ebay.com/itm/2-x-250K-OH...834?pt=LH_DefaultDomain_0&hash=item4ac01e5f3a and try them both out and see if either/both/neither are able to get a smooth operation. One problem with a spin a split in particular is that lower value pots are more audibly linear, but they're also higher load, so it's a trade off you wouldn't be able to avoid in this situation. Just buy an assortment of dual gang pots from China and try them out with alligator clips before committing with solder.

 

[DreX]

Re: Yet another wiring question

I did. It didn't work worth a darn.

What was the outcome?

 

[Artie]

Re: Yet another wiring question

It was like a very subtle tone control. There was less change in tone than the tone control. Not even close to sounding split to either coil. Mind you, I did mine a little different than you did. I'd have to search out that old diagram.

 

[DreX]

Re: Yet another wiring question

It was like a very subtle tone control. There was less change in tone than the tone control. Not even close to sounding split to either coil. Mind you, I did mine a little different than you did. I'd have to search out that old diagram.

Yeah that must have been different, because on the diagram I posted the split portion is bullet proof, it would split, but the coil bypass is another story, I'm not sure if that would be gradual or sudden, complete or partial. This would be a nifty mod for P-Rails if it worked, but I'd personally prefer a toggle switch that did " blade | blade + p-90 | p-90 ".

 

[JHN]

Re: Yet another wiring question

...at center, there would be 250k resistance from grounding out second coil, and 250k resistance from bypassing the first coil, hence it would be in series. In this case, true center (5 on the dial) might not be the most perfectly series, a center detent might be pointless, but also, the "on center" sound might account for most of the sweep anyway .

The problem of half or not full response in the middle detent as far as resistance control goes,I think has a solution if you get a pot with "MN" taper.
http://www.bourns.com/data/global/pdfs/Bourns_PDB182_Blend-Balance_Guitar_Pots_AppNote.pdf page 1 and 2 says it all
This one should work perfectly if Drex's wiring schematic indeed works.

 

[JHN]

Re: Yet another wiring question

At Drex;
It's obvious in your schematic that you use the upper deck to control the spin-a-split (what you call the split portion).Can you explain to me exactly how the resistance is used on the lower deck (which you call coil bypass) and how that affects the signal flow of the serial connection?

 

[DreX]

Re: Yet another wiring question

The way I have it drawn there is a serial/series connection, as + goes in one coil, that coil hops to the next, and then finally exits to ground.

You're right that the lower half of the dual gang is spin a split, and that's straight forward, it will knock out the second coil.

The idea with the top half of the pot is to allow the electric current to bypass the first coil by giving the electric current an alternate path of less resistance. At center, there would be enough resistance to cause the current to favor the coil, but if you turn the knob so that the wiper is all the way to the right, the coil will become more resistant than the pot, and so it will be bypassed, leaving only the second coil to produce sound. I just did a test with a 250k pot and what I found was that the bypass pot method works, but as I expected the transition isn't all that smooth, you get 90% of the change in the last 10% of the turn. 250k is too much, and so I'll revise my diagram and say this would probably would better with a 250k/250k linear dual gang pot:

http://www.ebay.com/itm/2-x-250K-OH...834?pt=LH_DefaultDomain_0&hash=item4ac01e5f3a

that would give 125k resistance in either direction at center, and that should make for a decent enough split/bypass sweep action. 125k ohms is more than enough resistance to make the current favor the first coil at center, and I use 100k pots for spin a split, 125k is close enough for that as well. Make sure it's *linear* and not audio taper, audio wouldn't give you even resistance split at center.