MOC7811 Slotted Opto Isolator Module

MOC7811 Slotted Opto Isolator Module is a versatile and indispensable component for non-contact object detection, speed sensing, and position encoding in various electromechanical systems. This module integrates an infrared LED emitter facing a phototransistor detector across a small gap, creating a highly reliable optical interruption sensor. Therefore, when an opaque object passes through the slot, it interrupts the light beam, causing the phototransistor output to switch states immediately. The MOC7811 effectively eliminates physical wear and bounce associated with mechanical switches, consequently, making it a superior choice for counting, feedback, and limiting applications where precision and durability are critical. Furthermore, its optical isolation ensures complete separation between the control electronics and the potentially noisy mechanical system.

Key Features:

• Non-Contact Sensing: Detects objects without physical touch, eliminating wear and extending the lifespan of the sensor and the moving parts.
• High-Speed Switching: The phototransistor output offers fast response times, making it ideal for high-speed counting and encoding applications.
• Digital Output Capability: Provides a clear transition between ON (light path clear) and OFF (light path blocked) states, simplifying interfacing with digital logic and microcontrollers.
• Optical Isolation: The internal emitter and detector are optically isolated, ensuring robust noise immunity from motors or mechanical interference.
• Gap Width: Features a standardized slot width optimized for common paper, thin metal, or plastic sensing applications.

Technical Specifications:

• Detection Principle: Transmissive Infrared (IR) Optical Sensing
• Emitter Type: Gallium Arsenide (GaAs) Infrared LED
• Detector Type: NPN Phototransistor
• Max Collector Current (I_C): 50 mA continuous
• Collector-Emitter Voltage (V_CEO): 30 V max
• Max Emitter Forward Current (I_F): 50 mA continuous
• Sensing Gap Width: ≈ 3.1 mm
• Operating Temperature Range: −40°C to +85°C

Mechanical Specifications:

• Package Type: Slotted Optical Switch (U-shaped housing)
• Mounting: PCB through-hole mounting via the side tabs.
• Housing Material: Opaque plastic, designed to block stray light interference.
• Output Connection: Standard 4-pin arrangement (Anode, Cathode, Collector, Emitter).

Dimensions:

• Body Length: ≈ 24.5 mm
• Body Width: ≈ 6.3 mm
• Body Height: ≈ 25.4 mm
• Slot Depth: ≈ 11.2 mm
• Pin Pitch (Between pins): 2.54 mm (0.1 inch)

Pinout and Wiring:

• Pin 1 (LED Anode): Connect to V_CC via a current-limiting resistor (R_limit) to drive the LED.
• Pin 2 (LED Cathode): Connect to GND or a control signal (e.g., MCU pin) to switch the LED on/off.
• Pin 3 (Phototransistor Emitter): Connect this pin directly to GND (Circuit Ground).
• Pin 4 (Phototransistor Collector): Connect this pin to V_CC via a pull-up resistor (R_pullup). The output signal is taken from this pin.
• Output Logic: The output (Pin 4) pulls HIGH when the light path is interrupted and LOW when the path is clear.

Datasheet Reference:

• Download ON Semiconductor MOC7811 Datasheet

Commonly Used in:

• 3D Printers and CNC Machines: Functions as a precise limit switch or end-stop detector.
• Motor Feedback Systems: Utilized with slotted wheels (encoders) to measure rotational speed and position.
• Printers and Copiers: Detects the presence of paper or monitors the paper path.

Applications:

• Position Sensing: Accurately determines the home position or limits of linear and rotational mechanisms.
• Speed and Flow Metering: Integrates with slotted disks or vanes to measure RPM or fluid flow rates.
• Object Counting: Provides reliable pulse generation for counting objects passing a specific point on a conveyor belt.
• Security and Vending: Detects coin or item passage in automated systems.

Equivalent Models:

• H22A1 (Lite-On): A common industry standard slotted optical switch offering similar specifications and mechanical dimensions.
• TCST2103 (Vishay): A close functional equivalent from Vishay, featuring a phototransistor output and a comparable 3.1 mm slot gap.
• KT05401 (Kodenshi): However, always verify the specific current transfer ratio (CTR) and gap size when choosing an equivalent part.

Package Includes:

• 1 x MOC7811 Slotted Opto Isolator Module