Bring the object closer, use a lighter target surface, or turn the potentiometer clockwise. Fluctuating power supply voltage or high electrical noise.
Absorb IR light. A pure matte black surface may not reflect enough light to trigger the sensor at all, a property frequently exploited in line-following robots where black tape represents a boundary line. Adjusting Sensitivity and Range Fc 51 Ir Sensor Datasheet
Supports a flexible range from 3.0V to 6.0V , making it compatible with both 3.3V (Raspberry Pi/ESP32) and 5V (Arduino) systems. Bring the object closer, use a lighter target
The object is too dark (absorbs IR) or outside the 30cm limit. Bring the object closer