SparkFun XBee Explorer Dongle Category_Gearmotors/30mm Diameter and you have the control

and you have the control system for a simple remote control rover or small autonomous robot

com/products/16466) Air Quality (Pressure

PID control for high accuracy

Another approach is to use a multimeter to measure the current draw of the sensor

the battery pack provides hours of power to rotate the gear wheel that brings the marbles up to the top of the spiral

SparkFun XBee Explorer Dongle Category_Gearmotors/30mm Diameter and you have the controlThis is the SparkFun XBee Explorer Dongle unit for the Digi XBee module line. With the XBee Explorer Dongle you can plug the unit directly into your USB port and have it act as a gateway between your computer and the XBee. No cables needed! This unit works with all XBee modules including the Series 1 and Series 2. 5, standard and Pro version. The on board voltage regulator is good up to 500mA. The highlight of this board is an FT231X USB to Serial