Offshoot from a question I had previously - What are your thoughts on providing power to a DC brushed motor via a switching regulator like the ones made by Linear Technology? They can be selected to work with a wide input voltage (3.4V to 42V) and regulate down to 5V for a motor in a very small package (3mm x 4mm). This would allow me to use a 5V motor. The servo that the motor is driving would be able to operate over my entire potential operating voltages (5-30V) instead of having versions specific of 5V, 12V, and 24V. I think that one potential compromise of this solution would be that the amp draw would be higher than if it was nominally a higher voltage motor. The power provided by the switching supply would run directly to MOSFETs that are controlled by a PWM signal from a MCU to vary the speed of the motor.
The whole point of doing this, if it would work, would be to be able to feed the servo a very wide input voltage, but the motor would always see 4.5V and perform the same regardless. So far, I haven't been able to find anything specific online regarding driving motors with switching power supplies.