switchable input capacitors

[xnery]

I've been working with a few different boosts and want to try making a boost with two choices of input capacitor, selectable by a two-position switch. Do I need to use a double-pole switch or a single-pole switch? Does anyone have a schematic example of this? I'd like to find out about it before I order extra parts.

Thanks

[Threefish]

I've done switchable caps using DPDT switches, like this:
http://www.putfile.com/pic.php?img=4895931
(it's the underside of the switch and it's six lugs - the oval things are the caps and their leads)
It's a bit rough, but I'm sure you get the idea. Where the single cap would be, solder in the middle lugs of a DPDT switch. On the pairs of outer lugs, solder in the two caps. Throwing the switch sends the signal through one of the caps. You could use a single pole switch, and where the second lot of lugs would be, solder one end of each cap to the wire that would go to the second middle lug. I use DPDT's so that you can easily change caps, instead of having to resolder the two-caps-plus-a-wire at one end if you want to change one or both. It's neater too.
I've also made a three way switch out of a centre-off DPDT by adding another cap to the middle lugs (not claiming this idea as my own, got it off someone here I think) :
http://www.putfile.com/pic.php?img=4896002
If A is a .05uF, B a .05uF and C a .082uF, you'll get .05uF in the middle position, .1uF in upper position (.05 + .05uF), and .132uF in the lower position (.05 + .082).
You can do all sorts of clever things like that with switches. You just have to be careful about lead length (to and from the switch) and noise if the leads are too long.
Most of my builds could feature 5 or 6 switches, but the number of variations can get very silly very quickly....