"FIG. 5 illustrates the circuitry for supplying variable voltage. Three power out lines 61, 62, and 63 are driven by the microprocessor. Signals from these power sources go to electrical switches such as MOSFET devices 64, 65, 66"

Variable voltage signals are conditioned from the Micro-Processor...then signaled to MOSFET devices..

This is not a device power issue..it's a signal condition..it's variably specific voltage signal conditions sent to MOSFETs....which then couple or de-couple circuits as needed....dependent upon the degree of voltage signaled.

As for the actual device power, it resides in the second power source to energise circuits when coupled.

doni