Automatic "liquid level control set" includes a pair of SXL liquid level sensors for high and low set point control of reservoirs, tanks etc. Connect the two sensors as shown in the diagram to any 5-24Vdc device (up to 1A) such as a relay or valve. Kit includes only the sensor set; a valve or relay must be provided. Electronic optical liquid sensors are durable, have no moving parts and are easy to maintain. LED illuminates body to indicate when they are activated. Other intelligent functions include "stable state" switching to detect splashing, one-second output debounce and error indication. Highly reliable and accurate solid state electronic optical level control system.