Cynergy3's OLS2, OLS5, and OLS7 series liquid-level sensors feature low-cost and high-reliability for general liquid sensing. Models are available with internal (OLS5) and external mounting (OLS2 and OLS7). The sensors are constructed using an infrared emitter and detector. Models are available with high and low transistor output. Extended temperature range models are also available.
App Note: Liquid Sensor - Pump control circuit for automatic tank filling