A voltage selector circuit may be coupled to transistors to protect one or more inputs of the transistor from exceeding a safe operating range. A location data determination algorithm is provided to a wireless device, where the algorithm determines a frequency at which the device interacts with network elements to determine its location. A ring gear of the first planetary gear train is connected to a second pumpmotor, and a ring gear of the second planetary gear train is connected to an output shaft. For example, an array of suitably functionalized nanoelectrodes can be incorporated into a small, integrated sensor system that can identify many species rapidly and simultaneously under field conditions in high-resistivity water, without the need for chemical addition to increase conductivity.