Sensing techniques that do not require a mechanical connection to the quantity being sensed. Such techniques rely instead on observing other properties associated with the quantities of interest, typically liquid levels or positional information. Electrical sensing techniques include measuring changing capacitance of a container to determine the level of liquid it contains, or using induction coils and magnetic induction to observe the position of a mechanical component. Other techniques for proximity sensing include sonar, ultrasonic range finding, and optical ranging. Non-contact sensing is generally used to avoid the risk of mechanical failure of the sensor.