The compact (0.4″ × 0.5″) D24V6F3 switching step-down (or buck) voltage regulator takes an input voltage between 4.8 V and 42 V and efficiently reduces it to 3.3 V while allowing for a maximum output current of 600 mA.
This set of wheelchair motors makes great heavy duty robot motors. One left motor and one right motor. They are right angle gear drives with a release and electric brakes. They are 24VDC and the operating speed is 120 RPM.