If I want to select between 9 and 18 V with a switch, can I do it like this, with just a SPDT?
(https://dl.dropboxusercontent.com/u/1042331/Pedals/pwr.PNG)
That should work. I use the RoadRage with breadboards all the time and just move a jumper to get the voltage I want. It's essentially the same thing you have drawn up with the switch. The only thing I do a little bit differently is that I pull the 9V from the connection on the board. The only thing I can see that this would do is it moves the 9V line a little closer to the 100µF cap. When I use the RoadRage, I usually leave the supply caps off of the effect I'm working on. So, it might make a bit of a difference when doing it this way.
Thanks Rob. I did not see it that way but yes, that could be a solution since the RR has two +9V pads.