What is a good way to switch an known DC voltage (between 2.4V and 24V) with unknown polarity using a 3.3V CMOS logic signal? The controlled signal will usually be driving low voltage DC motors. If the polarity was known I would just use a logic level MOSFET.
A relay would be the ideal, but energizing it uses too much power - I want to drive it for many hours from a CR2032 cell.