Madison Company”s O Series optical single-point, liquid-level detection switches are designed for use in noncoating liquids. The units provide accurate, repeatable switching-point detection with no moving parts. They operate with a phototransistor that provides a digital output indicating the presence or absence of liquid. The phototransistor is housed in the sensor tip, providing highly reliable performance in a compact design that is a good fit for applications where space is limited. Over 70 standard models are available, with both metal and plastic housings and various mounting configurations, as well as wire- and supply-current options. All are designed for easy installation and maintenance-free performance. Custom-engineered designs may also be requested by using Madison”s O Series specification sheet, available on the company”s Web site at