IR sensor

IR Proximity Sensor PCB

A custom PCB designed in KiCad 8 that detects nearby objects using an IR LED and photodiode pair, processed through an LM741 op-amp comparator circuit with adjustable sensitivity via a potentiometer.

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Features

• IR LED emitter and photodiode receiver pair for proximity detection
• LM741 op-amp configured as a comparator for clean digital output
• Adjustable sensitivity via 10kΩ potentiometer
• Output LED indicator on object detection
• Power LED indicator
• 3-pin connector output for integration with external systems

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Components

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Schematic

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PCB Layout

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3D Render

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How It Works

1. IR LED emits infrared light toward the target
2. Photodiode receives reflected IR light — resistance drops as light increases
3. Voltage at the op-amp non-inverting input (+) rises when object is detected
4. LM741 comparator switches output to HIGH when (+) exceeds the threshold set by the potentiometer at (−)
5. Output LED lights up indicating object detection

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Tools Used

• KiCad 10

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What I Learned

• How an op-amp comparator circuit works in a real PCB context
• Routing mixed analog and digital signals on a single board
• Using a potentiometer footprint for adjustable threshold setting
• Resolving DRC violations including board outline and unconnected tracks
• Exporting 3D render and Gerber files for manufacture