Can I use a regular on/on miniswitch for turning 18v mod on and off?
I wanna have this for my HSS guitar for some versitility.
And how would I wire the battery to it?
I think you could get away with a SPDT on-on switch (one row of contacts, but three contacts). Wire the negative of battery 1 to ground as normal, wire the positive from battery 1 AND the negative from battery 2 to the terminal corresponding to "9v" mode, wire the positive of battery 2 to the terminal corresponding to "18v" mode and then the power out to your pickups would be wired to the centre terminal.