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Optomax Basic – LLT200A3SH


Optomax Basic Range of Liquid Level Switch
  • OEM optics only solution
  • Low cost
  • MOQ of 500


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Supply Voltage (Vs) Any with suitable LED current limiting resistor
LED Forward Current (If) 10mA recommended
Output Signal Phototransistor open collector. Refer to circuit diagrams on datasheet
Operating Temperature -25 to +80ºC
Storage Temperatures -30 to +85ºC
Housing Materials Polysulfone (Standard)
or Trogamid
Sensor Termination 24AWG, 250mm PTFE wires, 8mm tinned
Operating Pressures 0 to 20bar (M10x1 thread)
or 0 to 7bar (All other threads)


Sensor mounted from inside the vessel (M10x1 thread)


Sensor mounted from outside the vessel (M12x1, 1/2″ SAE, 1/4″ NPT threads)



3-wire version

Basic 3 wire

4-wire version*

Basic 4 wire

*The 4-wire version provides galvanic isolation between the input (IR-LED) and the output (Phototransistor)


3-wire version

Wire Designation
Red LED Anode
Green Output
Blue 0V

4-wire version

Wire Designation
Red LED Anode
Green Output
Blue 0V LED
Black 0V Phototransistor


  • Optics only solution
  • Customer is responsible for interfacing the sensor to their application
  • 3-wire (common cathode/emitter) and 4-wire (galvanically isolated) versions avaliable
  • MOQ of 500 units
  • Polysulfone or Trogamid housing material options
  • Internal or external mounting options
  • High pressure option available


  • Solid state so no moving parts to cause unreliability
  • Small in size so they can be installed in applications where space is limited
  • Can detect tiny amounts of liquid when positioned correctly, ideal for leak detection
  • Fast response time
  • Repeatable switching point
  • LED current limiting resistor and phototransistor pull-up resistor can be built in to the sensor on request
  • Very robust permitting use in a wide range of fluids and chemicals
  • Low in cost for price sensitive applications


Liquid sensing 001_450

When in air the infrared light is reflected back to the detector


Liquid sensing 002_450

When in liquid the infrared light is refracted and the output switches

  • This field is for validation purposes and should be left unchanged.