Madison Company offers a very wide range of optical level switches made with different materials, mounting configurations, electrical outputs and switching operation for use in measuring liquids with a viscosity generally of less than 2,000 centipoise. It is therefore very important to fully understand your application to select the proper model. The optical liquid level sensors incorporate a phototransistor trigger, which provides a digital output that denotes the presence or absence of liquid. The mode of operation is derived from the principle of total internal reflection. An LED and phototransistor are housed within a plastic dome at the head of the device. When no liquid is present, light from the LED is internally reflected from the dome to the phototransistor. When liquid covers the dome, the effective refractive index at the dome-liquid boundary changes, allowing some light from the LED to escape. Thus the amount of light received by the phototransistor is reduced and the output switches, indicating the presence of liquid. This method of liquid level sensing is very fast, and almost instantaneous for water.

Benefits:

• Accurate, repeatable switching point with no moving parts
• Can be mounted in applications where space is limited
• Microprocessor compatible
• Easy to install, saving assembly time
• Reverse polarity, over voltage, short circuit and transient protection

Features:

• Solid state technology
• Small size
• Digital (TTL) output, open collector output or push pull output
• Pre-wired
• Electrically robust