Oh FFSFF!
The other day, like within the last week, I stayed up 'til 7am trying to get the routing for this very sort of thing sorted out on DIYLC (7-9 hrs?).
I wanted:
Circuit A
Circuit A > B
Circuit B
I tried 3PDT on-on-on briefly, then thought it'd have to be 4PDT on-on-on, then tried it with 4PDT on-off-on with my own "on-on" jumper-arrangement... AAUGH! GOOD GRIEF!
Taking JTEX's schematic (Thanks
@JTEX!), I've gone back to my DIYLC doc to fix what I thought was impossible without resorting to relay-switching:
Fixing this diagram up to present here, I realised what I was doing wrong the other night: I was only looking at the middle position even when I was working on the first or third position, which meant that Lugs 1&2 were ALWAYS connected whatever the lever-position ...
Once again, I encourage others not to work during sleep-deprivation. It's now nearly 5am and I've spent wayyyy too much time on this damn diagram, again!
Oh, and to try to clear up any confusion about the circuit switchcraft for those unfamiliar with on-on-on or DP3T...:
A "Dual-Pole Dual-Throw" (DPDT) is technically only on-off or on-on. A switch that has three positions — on-off-on or on-on-on — is a three-throw switch: SP3T, DP3T, 3P3T, and 4P3T...
However, most often on the forums people refer to any Dual-Pole Switch as a "DPDT"; There really isn't such a thing as a "DPDT on-on-on".
Same for the 3P3T and 4P3T, most people just refer to them as a dual-throw, whether they are or not.