Hi I hope someone out there in the the guitar world can help me. David Gilmour has a mod switch on his Black Strat for neck on Bridge on. Has anyone have the wiring schematics for this mod all and any help gratefully received.
The diagram ChrisK linked you to uses a push/pull pot to turn the bridge pup on/off. A push/pull pot is simply a pot with a DPDT on/on switch attached to its hiney.
You could use an on/off/on switch, but you'll then have a middle position which will be, ahhh, "off". Now, that switch could be wired, with the off position taking the switch out of the circuit, leaving you with whatever's selected on your regular pickup switch. But then you still have an extra position.
There are other ways of doing this mod, as ChrisK mentioned, and if you already have an on/off/on switch, there are some other options for that extra position.
You originally mentioned "neck on bridge on". It is not necessary to have both, as either a "neck on" or a "bridge on" will give you 7 of the 8 possible parallel combinations of three pickups. (the 8th one is "all off" which most folks don't want anyway- although "all off" is useful as a"standby" setting if one wants to leave a spare guitar plugged in onstage).
Solely doing the neck on mod only requires a SPST switch.
Using a three-position DPDT Center-Off (ON-OFF-ON) will work fine also, it just has an extra off position for this effect.
Now, one could use it to realize the following;
1. neck always on, in parallel with 5-way selection
2. 5-way selection
3. bridge always on, in parallel with 5-way selection
This gives a bit more flexibility if desired.
You could also use the other pole (what I just described requires only a SPDT Center-Off) to switch in the middle tone (!or the neck tone) to also work on the bridge as well on the 5-way switch as well as add in the neck pickup.
We can help you break (er, uh, yeah that's it, improve) your guitar in numerous ways, what more might you have in mind? We love to "help" folks get deep into trouble and then help them out of it! We might even "infect"* some of these folks to stick around and become full-time helpers of others.
* Infect = Compulsive (re)Wiring Dementia
And newey, sorry about editing your post. I'd originally edited it inadvertently to add my welcome message.