Hi Laurie

> Easy, get a (build) a power supply that uses a transformer with dual
> primary windings (2 x 115VAC) and a suitable mains selector switch which
> simply puts the windings in parallel or series.

It is not necessary to build a new one:
http://www.doepfer.de/faq/a100_faq.htm#Modification%20mains%20voltage
Nevertheless this should be done definitely only by knowledged experts
and or authorizied technicians.

Florian